•
99 mTc Sulfur
Further Evaluation of Colloid Accumulation in Rejecting Renal Transplants in Man and a Canine Model 1
•
Nuclear Medicine
Erica A. George, M.D., John E. Codd, M.D., William T. Newton, M.D., Robert E. Henry, M.D., and Robert M. Donati, M.D. Renal transplant accumulation of 99mTC sulfur colloid was evaluated in 41 patients. Ninety-five examinations were performed comparing transplant with bone marrow activity and clinical or pathological diagnosis. 9 9mTc sulfur colloid accumulated in acute or chronic rejection as long as the vascular supply of the grafted kidney was not severely impaired. Accumulation was marked in chronic rejection, slight in acute rejection and absent in normally functioning transplants or in those with acute tubular necrosis. In the 10 dog models, no accumulation was seen in autografted transplants and early accumulation was demonstrated within the hyperacutely rejecting kidneys of allografted dogs. INDEX TERMS: Kidneys, blood supply. Kidneys, necrosis. Kidneys, radionuclide studies • Kidneys, transplantation Radiology 116:121-126, July 1975
• is widely accepted as a therapeutic measure for patients with intractable renal disease. The most frequent causes of decreased renal function following transplantation are acute tubular necrosis, transplant rejection, or acute tubular necrosis superimposed by rejection. It is imperative to differentiate transplant rejection from acute tubular necrosis since the therapeutic modalities employed in correction are quite different. The value of assessing renal transplant function and viability by selective radionuclide studies has been extensively explored (1-4). Several investigators have reported that radionuclide methods may be useful in differentiating acute transplant rejection from acute tubular necrosis by the simultaneous utilization of radioiodinated Hippuran in the assessment of transplant tubular function and 99 mTC pertechnetate in the assessment of the circulatory integrity of the transplant (5-8). In a recent
preliminary report, we detailed our initial experience in 21 patients with renal transplant accumulation of 9 9mTc sulfur colloid as a clinical aid in the differentiation of renal transplant rejection from acute tubular necrosis (9-10). In this paper, we present our experience with 9 9mTC sulfur colloid accumulation in the evaluation of renal transplants in 41 patients, and the results of studies with the radiocolloid in 10 mongrel dogs prepared with renal allografts or autografts.
R
ENAL TRANSPLANTATION
Fig. 1.
METHODS AND MATERIALS
Human Studies
The patients were under the care of the staff of the Organ Transplant Unit of the Surgical Service at the St. Louis Veterans Administration Hospital, and informed consent was obtained from each patient. All were ex-
Nuclear images of human renal transplants. A, No evidence of 99mTc sulfur colloid accumulation; B, slight accumulation; and C, marked accumulation.
1 From the Nuclear Medicine and Surgery Services, S1. Louis Veterans Administration Hospital; the Section of Nuclear Medicine of the Department of Internal Medicine, the Department of Surgery, S1. Louis University; and the Department of Surgery, Washington University School of Medicine, St. Louis, Mo. Presented in part at the Society of Nuclear Medicine Meeting, San Diego, Calif., June 1974. shan
121
122
ERICA
A. GEORGE
AND OTHERS
2000
Table I:
Renal Transplant Accumulation of 99mTc Sulfur Colloid in 95 Examinations in 41 Patients
1 Diagnosis
200
o
TIME
A
10 min.
_-----0
TIME
B
10 min.
Fig. 2. Time-activity curves of 99mTc sulfur colloid graft vascular transit. Counts over the canine transplant were obtained at 10-second intervals for 10 minutes following l.v. bolus administration of 99mTc sulfur colloid. A. Normal graft vascular transit. B. No evidence of graft vascular transit due to impaired transplant vascularity.
amined with an Anger-type scintillation camera- 15 to 30 minutes following the intravenous administration of 1-3 mCi of 99mTc sulfur collold''. In all instances, 50,000 counts were accumulated over the transplant site in the right or left iliac fossa, and the time of exposure recorded. The field of view included portions of the pelvis and vertebral column, and occasionally the tip of the right lobe of the liver and/or the interior pole of the spleen. Accumulation of radiocolloid by the renal transplant was evaluated subjectively by comparing the transplant activity with pelvic bone marrow activity and was characterized as either absent, slight, or marked accumulation (Fig. 1). Similar activity in the renal transplant and bone marrow represented slight accumulation while transplant activity appreciably higher than that of bone marrow was graded as marked accumulation. Clinical criteria, clinical course, elapsed time after transplantation and, in selected instances, renal biopsy, selective renal arteriography or pathological examination of the removed transplant, were utilized in establishing the clinical diagnosis of acute rejection, acute tubular necrosis, nephrotic syndrome, chronic rejection, or normal function. The degree of transplant accumulation of radiocolloid or absence of accumulation was correlated with the clinical diagnosis at the time of examination. Radiohippuran and 99mTc-pertechnetate studies (8) were also performed in each instance. A comparison of all three.radionuclide studies provides the basis of a separate report (11). Canine Studies
Female adult mongrel dogs with an average weight of 19 kg (10-29 kg range) were used. The principles of laboratory animal care as promulgated by the National Society for Medical Research were observed. Follo~ing light tranqulllzation" and general anesthesla", 10 immuSearle Radiographies (formerly Nuclear Chicago) Pho Gamma III. E. R. Squibb and Sons, Inc., New Brunswick, N. J. Per cent free pertechnetate (99mTc04) was determined by ascending paper chromatography to be less than 1 %. 4 Rompun® (xylazine hydrochloride with methylparaben), i.v. doses of 1 mg/kg, Baychem Corp., Kansas City, Mo. S Pentobarbital sodium 10 mg/kg l.v., sustained with Halothone® (methoxy fluorothane), Eli Lilly & Co., Indianapolis, Ind. 2
3 Tesuloid~\
July 1975
Normal function Acute tubular necrosis Acute rejection Chronic rejection Nephrotic syndrome
Number Absent Slight Marked of Accu- Accumu- AccuExammulation lation mulation inations
14 15 6
1 0
5
4 25 0
1
0
19
1
20
4 18 1
35 19 2
nologically unmodified dogs were prepared surgically with the renal transplant grafted to an internal iliac or internal carotid artery. Seven dogs received renal allografts following bilateral nephrectomy and 3 control animals received renal autografts. The dogs were studied daily for at least two consecutive days and maximally up to seven days. Following pentobarbital anesthesia", an intravenous catheter was placed in a peripheral vein and 0.9 % saline solution infused. The scintillation camera fitted with a low energy parallel-hole collimator was placed over the transplant site and a bolus of 3 mCi of 9 9mTC sulfur colloid was injected intravenously via the catheter. To evaluate graft vascularity, kinetic data were recorded on videotape for 10 minutes for later recall after the accumulation of 50,000 counts for a static image. The kinetic data were then recalled from an electronically integrated window placed over the transplant site in the pelvis or the neck and displayed as time-activity curves at 10-second intervals (Fig. 2). Transplants grafted to the internal carotid artery provided better transplant definition when visualized with 99mT C sulfur colloid because the liver and spleen edge did not compete for count accumulation (Fig. 3). In selected instances, contact gross autoradiographs (12) and microscopic autoradiographs (13) were obtained from the excised renal grafts following sacrifice of the animal recipient. RESULTS
Human Studies
Clinical diagnosis, the degree or absence of transplant accumulation of 99 mTC sulfur colloid and the number of examinations are summarized in Table I. There were 19 instances of normal transplant function: 14 had absent and 5 had slight radiocolloid accumulation; the 5 instances of slight accumulation were either preceded or followed by a clinically diagnosed rejection episode within seven days. There were 20 instances of acute tubular necrosis; 15 had no accumulation, 4 had slight radiocolloid transplant accumulation, and 1 had marked accumulation. Three of the 4 patients with slight accumulation presented signs of acute rejection a few days later; the reason for the accumulation in the remaining patient was unexplained. The patient with marked accumulation experienced a complicated subsequent course with repeated 6
Pentobarbital sodium, 10 mg/kg Lv.
Vol. 116
99mTc SULFUR COLLOID ACCUMULATION IN REJECTING RENAL TRANSPLANTS
123
Nuclear Medicine
Fig. 3. 99mTc sulfur colloid accumulation in canine renal allografts. Note progressive increase in accumulation with time following allografting. Delineation is better in the carotid transplant.
Fig. 4. Gross radioautograph of hyperacute rejecting canine allograft. Following i.v. administration of 99mTc sulfur colloid, radioactivity is found in areas of renal vasculature and renal thrombosis. (See text.) . Fig. 5. Microradioautograph of thrombus in intralobar artery in hyperacute rejecting canine allograft. Following i.v, administration of 99mTc sulfur colloid, grains are found trapped within the intravascular thrombosis. Note scattered inflammatory cells. .
episodes of rejection and finally urinary extravasation. Following transplant nephrectomy five weeks later, pathological diagnosis of the excised graft was chronic rejection. There were 35 instances of acute rejection: 25 of these exhibited slight accumulation of radiocolloid in the renal transplant, 4 had marked accumulation, and 6 had no evidence of accumulation. Four of the 6 patients who had acute rejection and no accumulation had nonvisualizing transplants when studied with 99mTC pertechnetate and 131/-Hippuran, and the remaining 2 had equivocal clinical signs of rejection. The 4 cases diagnosed clinically as acute rejection demonstrating
marked radiocolloid accumulation were subsequently clinically diagnosed as chronic rejection. There were 19 instances of chronic rejection, 18 of which demonstrated marked transplant accumulation of radiocolloid. These particular cases of chronic rejection and marked accumulation presented only slight pattern abnormalities when studied with pertechnetate or Hippuran and transplant function was not severely impaired clinically. The one patient with chronic rejection and no accumulation of 99 mTc sulfur col/oid had a non-tunctlon-: ing transplant clinically and failed to concentrate Hippuran or pertechnetate. Pathological examination of the excised graft from this patient revealed end-stage
124
ERICA
Table II: Dog
#
A. GEORGE
Serial Examinations of Three Autografted Dogs Graft Days Graft TSC "Vascular" Post-Graff ng Accu mu lation Transit of TSC
2 4 5
1
6
7 2 4 5
2
6
7 2 3
3
4
+ + + + + + + + + + + + +
0
0 0 0 0 0 0 0 0 0 0 0 0
Pathologyat Sacrifice
Normal
Normal
Normal
chronic rejection with diffuse cortical scarring and loss of functional vascularity and renal parenchyma. We have presently no clear explanation for the transplant accumulation of the radiocolloid in the 2 patients with nephrotic syndrome, unless one considers posttransplant nephrotic syndrome as an - expression of chronic-rejection (14). To summarize: there was essentially no unexplained transplant accumulation of 99 mTc sulfur colloid in patients with normal functioning renal transplants or transplants with acute tubular necrosis. Acute rejection was characterized by slight and chronic rejection by marked accumulation. Canine Studies
There was no evidence of radiocolloid accumulation within the renal transplants of the 3 control autografted
Table III: Dog No.
1
2
4
5
6
Graft "Vascular" Transit of TSC
1 2
0 0
+ + + +
4 1 2 3
2 3
2 3 3 4
5 6 2 4
+ + 0 0
+ + + + + + + + +0 +
1
0 0 0
2
0
3
0 0
5 7
Serial Examinations of Seven Allografted Dogs Graft TSC Accu m ulation
3
4
July 1975
dogs at any time from the second to the seventh postgrafting day for a total of 13 examinations. All studies demonstrated a vascular transit phase of 99mTc sulfur colloid and all grafts were normal on pathological examination (Table II). Serial examinations of 4 of the allografted nephrectomized dogs [Dogs 1-4 (Table III)] whose grafts demonstrated uncomplicated acute rejection on pathological examination, exhibited radiocolloid accumulation in the transplant beginning on the second or third post-grafting day. Graft vascular transit of 99mTc sulfur colloid was consistently demonstrated in each examination. Two of the allografted dogs [Dogs 5 and 6] initially showed radiocolloid accumulation followed by absent accumulation, at which time graft vascular transit of 99rntc sulfur colloid could not be demonstrated. Pathological examination revealed graft rejection and anemic necrosis in Dog 5 and graft rejection, necrosis, and renal vein thrombosis in Dog 6. In Dog 7, graft accumulation and graft vascular transit of 99mTc sulfur colloid could not be demonstrated at any time, indicating severely impaired transplant vascularity already present on the first post-grafting day. Pathological examination revealed transplant necrosis secondary to renal artery and vein thrombosis. Gross autoradiographs of the renal transplants of those dogs which showed uncomplicated rejection at the time of sacrifice (Fig. 4) presented an outline of the larger intrarenal vasculature ··mcluding interlobar, arcuate, and interlobular vessels. Grossly visible radioactive thrombi were seen focally in interlobar vessels, subcapsularly, and at the site of the surgical anastomosis at the transplant hilus. Microscopically, radioactivity was concentrated in glomerular fibrin deposits and in areas
Days Post-Grafti ng
4 3
AND OTHERS
Pathology at Sacrifice
Acute rejection
+
+ + + + + + + + + +
Acute rejection
Acute rejection Acute rejection Acute rejection, anemic necrosis
0
+ 0 0
a 0 0 0
Acute rejection, hemorrhagic necrosis & renal vein thrombosis Marked anemic necrosis, renal artery and vein thrombosis
Vol.
116
99mTC SULFUR COLLOID ACCUMULATION IN REJECTING RENAL TRANSPLANTS
of vasculitis associated with endothelial proliferation and fibrin thrombosis (Fig. 5). No radioactivity was found in tubular lumina, in tubular epithelial cells or in interstitial connective tissue and inflammatory infiltrate.
DISCUSSION The recognition of renal transplant rejection, particularly in the immediate post-grafting period, is often difficult. Clinical and laboratory evaluation frequently offers little certitude of pathophysiologic events taking place in the transplant. Clinical diagnosis is further clouded by the frequency of acute tubular necrosis following cadaver graft transplantation (15). In addition, renal artery thrombosis, ureteric obstruction, or intercurrent septicemia may clinically mimic acute rejection (16, 17). From the therapeutic and prognostic standpoint, it is important to differentiate acute rejection from acute tubular necrosis and renal artery thrombosis in the early post-grafting period and to differentiate acute from chronic rejection in long-term surviving grafts (18, 19). Most radioagents have not demonstrated a high degree of reliability in diagnosing renal transplant rejection. Many radiopharmaceuticals, including radioiodinated 169 Yb-EDTA or -DTPA complexes, radioxe· Hippuran, non, radiomercury-Iabeled chlormerodrin, 113mln, 99mT C pertechnetate, or radioiodinated fibrinogen, have been used to demonstrate specific transplant functions. The utilization of two radioagents to assess post-renal transplant complications, particularly rejection, has been favored by many investigators (1-8). Sequential dual isotope renography with 131 1Hippuran and 99mTc pertechnetate provides a method of evaluating transplant tubular function and transplant vascularity. Certain pattern abnormalities favor either rejection or acute tubular necrosis but the diagnostic accuracy is not at a desirable level (8). 131 1or 1251-labeled fibrinogen appears to be the primary agent specific for renal transplant rejection. Its general use in the diagnosis of renal transplant rejection however has been hampered by the potential hazard of serum hepatitis in man, the necessity of a 24-hour delay following administration for optimal imaging, the narrow range of normal-to-abnormal per cent of transplant uptake, and poor imaging qualities (20, 21). In the present study, a simple reproducible technique for the diagnosis of renal transplant rejection is presented. Essentially, only those renal transplants undergoing either acute or chronic rejection accumulate 99mTc sulfur colloid. In patients with normally functioning renal transplants or acute tubular necrosis, radiocolloid is not accumulated within the renal transplant. Care must be exercised in order to establish the circulatory status of the transplant since in instances of impaired graft vascularity, the delivery of the radiocolloid is likewise impaired. The determination of graft vascular transit of 99mrc sulfur colloid or, alternatively, transplant perfusion with 99mT C pertechnetate provides information as to the circulatory integrity of the graft, thus separating
125
Nuclear Medicine
functioning transplants from those without function in cases without radiocolloid accumulation. Except for one instance, all cases of chronic rejection exhibited slight to moderate functional impairment and radiocolloid was accumulated more prominently than in transplants undergoing acute rejection at the time of examination. We have postulated that the generally marked interstitial edema and inflammatory infiltrate characteristic of acute rejection-, which are minimal in chronic rejection (22), cause additional vascular compromise and thus lead to less radiocolloid accumulation during acute as compared to chronic rejection. Assuming that the colloidal deposit in the usual sites, such as the liver, spleen and bone marrow, remains unchanged, a fine balance between functional renal vasculature and accumulation sites probably determines the amount of radiocolloid accumulation in acutely and chronically rejecting transplants. This hypothesis is further supported by canine studies. The vascular and glomerular deposit of radioactivity in fibrin thrombosis demonstrated autoradiographically in the hyperacute rejecting canine renal transplants suggests that radiocolloid is trapped within the network of forming fibrin thrombosis. In rejection, the formation of intravascular fibrin thrombosis, thrombolysis or organization is a continuous dynamic process and its net effect depends on the cellular and humeral immune state of the graft recipient (23). As demonstrated in canine transplants, graft vascular transit depends on functional extra- and intrarenal vascularity, and graft radiocolloid accumulation depends on effective vascular transit of 99mrc sulfur colloid and active intrarenal vascular transplant thrombosis.
SUMMARY The accumulation of 99mTc sulfur colloid by renal transplants signals rejection and continues as long as the vascular supply is not severely compromised. Acute rejection is represented by slight radiocolloid accumulation, and chronic rejection by marked accumulation when compared to bone marrow activity. Necrotic transplants in acute rejection and those fibrosed secondary to chronic rejection do not accumulate 99mrc sulfur colloid. In a canine transplant model, vascular transit and graft accumulation of radiocolloid was not demonstrated with graft necrosis following hyperacute rejection or when renal artery thrombosis was a post-grafting complication. Radioautographic studies of hyperacutely rejecting canine grafts demonstrated 99mTc sulfur colloid radioactivity trapped in areas of intravascular and glomerular fibrin thrombosis.
REFERENCES 1. Blaufox MD, Merrill JP: Evaluation of renal transplant function by iodohippurate sodium 1-131. JAMA 202:575-578 13 Nov 1967 2.
'
Gedgaudas E, White RI Jr, Loken MK: Radiology in renal transplantation. Radiol Clin N Am 10:529-544, Dec 1972
126
ERICA
A. GEORGE
3. HOr G. Pabst HW. Pfeifer KJ. et al: Radionuclides in renal transplantation. J Nucl Med 13:795-800, Nov 1972 4. Staab EV, Hopkins J. Patton DO, et al: The use of radionuclide studies in the prediction of function in renal failure. Radiology 106:141-146, Jan 1973 5. Weiss ER. Blahd WH, Winston MA, et al: Scintillation camera in the evaluation of renal transplants. J Nucl Med 11:69-77, Feb 1970 6. Staab EV, Whittier F, Patton DO, et al: Early evaluation of cadaver renal allotransplant by means of radionuclide imaging. Radiology 106:147-151, Jan 1973 7. Rosenthal L, Mangel R. Lisbona R, et al: Diagnostic applications of radiopertechnetate and radiohippurate imaging in postrenal transplant complications. Radiology 111:347-358, May 1974 8. Solanc-Georqe EA, Anderson CA. Codd JE, et al: Differentiation of acute tubular necrosis and rejection by dual radionuclide renography. [In] Proceedings of the Clinical Dialysis and Transplant Forum, Vol III, Schreiner GE, Diamond LK, Ryan JP, ed. Washington, D.C., Georgetown University Press, 1974, pp 77-84 9. George EA, Codd JE, Newton WT, et al: Visualization of rejecting renal transplants with 99mTc sulfur colloid (TSC). J Nucl Med 15:493. 1974 (abst) . 10. Solaric-George EA, Fletcher JW, Newton WT, et al: Renal accumulation of 99mTc sulfur colloid in transplant rejection. Radiology 111:465-466, May 1974 11. George EA, Newton WT, Henry RE. et al: Triple radioagent assessment of renal transplant rejection. (In preparation) 12. Donati RM, Berman AR, Jervis HR, et al: Absorption of iron following x-irradiation of the exteriorized small intestine. Proc Soc Exp Bioi Moo 130:822-827, Mar 1969 13. Tilden RL, Jackson J Jr, Enneking WF, et al: 99mTc_poly_ phosphate: histological localization in human femurs by autoradiography. J Nucl Med 14:576-578, Aug 1973 14. Harlan WR Jr, Holden KR, Williams GM. et al: Proteinuria
AND OTHERS
July 1975
and nephrotic syndrome associated with chronic rejection of kidney transplants. New Eng J Med 277:769-776, 12 Oct 1967 15. Branch RA, Coles GA, Eynon A, et al: The use of radioactive hippuran in the management of cadaveric renal transplants. Br J Radiol 44:697-704, Sep 1971 16. Figueroa JE, Maxfield WS, Batson HM Jr, et al: Radioisotope renal function studies in human renal allografts: value in the differential diagnosis of oliguria in the presence of obstructive disease with and without urinary extravasation. J Urol 100: 104-1 08, Aug 1968 17. Malek GH, Uehling DT, Daouk AA, et al: Urological complications of renal transplantation. J Urol 109: 173-176, Feb 1973 18. Simmons RL, Khellstrand CM, Najarian JS: Transplantation: Kidney, Section II: Technique, Complication and Results. Philadelphia, Lea and Febinger, 1972, pp 462-480 19. Williams GM, Lee HM, Weymouth RF, et al: Studies in hyperacute and chronic renal homograft rejection in man. Surgery 62:204-212, Jul1967 20. Winston MA, Weiss ER, 81ahd WH, et al: Use of 131-I-fibrinogen in detection of renal transplant rejection. Invest Urol 9: 119-123, Sep 1971 21. Howard RJ, Sutherland DER, Najarian JS: Detection of renal allograft rejection with (125-1) fibrinogen. J Surg Res 15:251254, Oct 1973 22. Busch GJ, Galvanek EG, Reynolds ES Jr: Human renal allografts. Analysis of lesions in long-term survivors. Hum Pathol 2: 253-298, Jun 1971 23. Balch CM, Diethelm AG: The pathophysiology of renal allograft rejection: a collective review. J Surg Res 12:350-377, May 1972 Nuclear Medicine Service (172-JC) St. Louis Veterans Administration Hospital S1. Louis, Mo. 63125
99 mTc Sulfur
Further Evaluation of Colloid Accumulation in Rejecting Renal Transplants in Man and a Canine Model 1
•
Nuclear Medicine
Erica A. George, M.D., John E. Codd, M.D., William T. Newton, M.D., Robert E. Henry, M.D., and Robert M. Donati, M.D. Renal transplant accumulation of 99mTC sulfur colloid was evaluated in 41 patients. Ninety-five examinations were performed comparing transplant with bone marrow activity and clinical or pathological diagnosis. 9 9mTc sulfur colloid accumulated in acute or chronic rejection as long as the vascular supply of the grafted kidney was not severely impaired. Accumulation was marked in chronic rejection, slight in acute rejection and absent in normally functioning transplants or in those with acute tubular necrosis. In the 10 dog models, no accumulation was seen in autografted transplants and early accumulation was demonstrated within the hyperacutely rejecting kidneys of allografted dogs. INDEX TERMS: Kidneys, blood supply. Kidneys, necrosis. Kidneys, radionuclide studies • Kidneys, transplantation Radiology 116:121-126, July 1975
• is widely accepted as a therapeutic measure for patients with intractable renal disease. The most frequent causes of decreased renal function following transplantation are acute tubular necrosis, transplant rejection, or acute tubular necrosis superimposed by rejection. It is imperative to differentiate transplant rejection from acute tubular necrosis since the therapeutic modalities employed in correction are quite different. The value of assessing renal transplant function and viability by selective radionuclide studies has been extensively explored (1-4). Several investigators have reported that radionuclide methods may be useful in differentiating acute transplant rejection from acute tubular necrosis by the simultaneous utilization of radioiodinated Hippuran in the assessment of transplant tubular function and 99 mTC pertechnetate in the assessment of the circulatory integrity of the transplant (5-8). In a recent
preliminary report, we detailed our initial experience in 21 patients with renal transplant accumulation of 9 9mTc sulfur colloid as a clinical aid in the differentiation of renal transplant rejection from acute tubular necrosis (9-10). In this paper, we present our experience with 9 9mTC sulfur colloid accumulation in the evaluation of renal transplants in 41 patients, and the results of studies with the radiocolloid in 10 mongrel dogs prepared with renal allografts or autografts.
R
ENAL TRANSPLANTATION
Fig. 1.
METHODS AND MATERIALS
Human Studies
The patients were under the care of the staff of the Organ Transplant Unit of the Surgical Service at the St. Louis Veterans Administration Hospital, and informed consent was obtained from each patient. All were ex-
Nuclear images of human renal transplants. A, No evidence of 99mTc sulfur colloid accumulation; B, slight accumulation; and C, marked accumulation.
1 From the Nuclear Medicine and Surgery Services, S1. Louis Veterans Administration Hospital; the Section of Nuclear Medicine of the Department of Internal Medicine, the Department of Surgery, S1. Louis University; and the Department of Surgery, Washington University School of Medicine, St. Louis, Mo. Presented in part at the Society of Nuclear Medicine Meeting, San Diego, Calif., June 1974. shan
121
122
ERICA
A. GEORGE
AND OTHERS
2000
Table I:
Renal Transplant Accumulation of 99mTc Sulfur Colloid in 95 Examinations in 41 Patients
1 Diagnosis
200
o
TIME
A
10 min.
_-----0
TIME
B
10 min.
Fig. 2. Time-activity curves of 99mTc sulfur colloid graft vascular transit. Counts over the canine transplant were obtained at 10-second intervals for 10 minutes following l.v. bolus administration of 99mTc sulfur colloid. A. Normal graft vascular transit. B. No evidence of graft vascular transit due to impaired transplant vascularity.
amined with an Anger-type scintillation camera- 15 to 30 minutes following the intravenous administration of 1-3 mCi of 99mTc sulfur collold''. In all instances, 50,000 counts were accumulated over the transplant site in the right or left iliac fossa, and the time of exposure recorded. The field of view included portions of the pelvis and vertebral column, and occasionally the tip of the right lobe of the liver and/or the interior pole of the spleen. Accumulation of radiocolloid by the renal transplant was evaluated subjectively by comparing the transplant activity with pelvic bone marrow activity and was characterized as either absent, slight, or marked accumulation (Fig. 1). Similar activity in the renal transplant and bone marrow represented slight accumulation while transplant activity appreciably higher than that of bone marrow was graded as marked accumulation. Clinical criteria, clinical course, elapsed time after transplantation and, in selected instances, renal biopsy, selective renal arteriography or pathological examination of the removed transplant, were utilized in establishing the clinical diagnosis of acute rejection, acute tubular necrosis, nephrotic syndrome, chronic rejection, or normal function. The degree of transplant accumulation of radiocolloid or absence of accumulation was correlated with the clinical diagnosis at the time of examination. Radiohippuran and 99mTc-pertechnetate studies (8) were also performed in each instance. A comparison of all three.radionuclide studies provides the basis of a separate report (11). Canine Studies
Female adult mongrel dogs with an average weight of 19 kg (10-29 kg range) were used. The principles of laboratory animal care as promulgated by the National Society for Medical Research were observed. Follo~ing light tranqulllzation" and general anesthesla", 10 immuSearle Radiographies (formerly Nuclear Chicago) Pho Gamma III. E. R. Squibb and Sons, Inc., New Brunswick, N. J. Per cent free pertechnetate (99mTc04) was determined by ascending paper chromatography to be less than 1 %. 4 Rompun® (xylazine hydrochloride with methylparaben), i.v. doses of 1 mg/kg, Baychem Corp., Kansas City, Mo. S Pentobarbital sodium 10 mg/kg l.v., sustained with Halothone® (methoxy fluorothane), Eli Lilly & Co., Indianapolis, Ind. 2
3 Tesuloid~\
July 1975
Normal function Acute tubular necrosis Acute rejection Chronic rejection Nephrotic syndrome
Number Absent Slight Marked of Accu- Accumu- AccuExammulation lation mulation inations
14 15 6
1 0
5
4 25 0
1
0
19
1
20
4 18 1
35 19 2
nologically unmodified dogs were prepared surgically with the renal transplant grafted to an internal iliac or internal carotid artery. Seven dogs received renal allografts following bilateral nephrectomy and 3 control animals received renal autografts. The dogs were studied daily for at least two consecutive days and maximally up to seven days. Following pentobarbital anesthesia", an intravenous catheter was placed in a peripheral vein and 0.9 % saline solution infused. The scintillation camera fitted with a low energy parallel-hole collimator was placed over the transplant site and a bolus of 3 mCi of 9 9mTC sulfur colloid was injected intravenously via the catheter. To evaluate graft vascularity, kinetic data were recorded on videotape for 10 minutes for later recall after the accumulation of 50,000 counts for a static image. The kinetic data were then recalled from an electronically integrated window placed over the transplant site in the pelvis or the neck and displayed as time-activity curves at 10-second intervals (Fig. 2). Transplants grafted to the internal carotid artery provided better transplant definition when visualized with 99mT C sulfur colloid because the liver and spleen edge did not compete for count accumulation (Fig. 3). In selected instances, contact gross autoradiographs (12) and microscopic autoradiographs (13) were obtained from the excised renal grafts following sacrifice of the animal recipient. RESULTS
Human Studies
Clinical diagnosis, the degree or absence of transplant accumulation of 99 mTC sulfur colloid and the number of examinations are summarized in Table I. There were 19 instances of normal transplant function: 14 had absent and 5 had slight radiocolloid accumulation; the 5 instances of slight accumulation were either preceded or followed by a clinically diagnosed rejection episode within seven days. There were 20 instances of acute tubular necrosis; 15 had no accumulation, 4 had slight radiocolloid transplant accumulation, and 1 had marked accumulation. Three of the 4 patients with slight accumulation presented signs of acute rejection a few days later; the reason for the accumulation in the remaining patient was unexplained. The patient with marked accumulation experienced a complicated subsequent course with repeated 6
Pentobarbital sodium, 10 mg/kg Lv.
Vol. 116
99mTc SULFUR COLLOID ACCUMULATION IN REJECTING RENAL TRANSPLANTS
123
Nuclear Medicine
Fig. 3. 99mTc sulfur colloid accumulation in canine renal allografts. Note progressive increase in accumulation with time following allografting. Delineation is better in the carotid transplant.
Fig. 4. Gross radioautograph of hyperacute rejecting canine allograft. Following i.v. administration of 99mTc sulfur colloid, radioactivity is found in areas of renal vasculature and renal thrombosis. (See text.) . Fig. 5. Microradioautograph of thrombus in intralobar artery in hyperacute rejecting canine allograft. Following i.v, administration of 99mTc sulfur colloid, grains are found trapped within the intravascular thrombosis. Note scattered inflammatory cells. .
episodes of rejection and finally urinary extravasation. Following transplant nephrectomy five weeks later, pathological diagnosis of the excised graft was chronic rejection. There were 35 instances of acute rejection: 25 of these exhibited slight accumulation of radiocolloid in the renal transplant, 4 had marked accumulation, and 6 had no evidence of accumulation. Four of the 6 patients who had acute rejection and no accumulation had nonvisualizing transplants when studied with 99mTC pertechnetate and 131/-Hippuran, and the remaining 2 had equivocal clinical signs of rejection. The 4 cases diagnosed clinically as acute rejection demonstrating
marked radiocolloid accumulation were subsequently clinically diagnosed as chronic rejection. There were 19 instances of chronic rejection, 18 of which demonstrated marked transplant accumulation of radiocolloid. These particular cases of chronic rejection and marked accumulation presented only slight pattern abnormalities when studied with pertechnetate or Hippuran and transplant function was not severely impaired clinically. The one patient with chronic rejection and no accumulation of 99 mTc sulfur col/oid had a non-tunctlon-: ing transplant clinically and failed to concentrate Hippuran or pertechnetate. Pathological examination of the excised graft from this patient revealed end-stage
124
ERICA
Table II: Dog
#
A. GEORGE
Serial Examinations of Three Autografted Dogs Graft Days Graft TSC "Vascular" Post-Graff ng Accu mu lation Transit of TSC
2 4 5
1
6
7 2 4 5
2
6
7 2 3
3
4
+ + + + + + + + + + + + +
0
0 0 0 0 0 0 0 0 0 0 0 0
Pathologyat Sacrifice
Normal
Normal
Normal
chronic rejection with diffuse cortical scarring and loss of functional vascularity and renal parenchyma. We have presently no clear explanation for the transplant accumulation of the radiocolloid in the 2 patients with nephrotic syndrome, unless one considers posttransplant nephrotic syndrome as an - expression of chronic-rejection (14). To summarize: there was essentially no unexplained transplant accumulation of 99 mTc sulfur colloid in patients with normal functioning renal transplants or transplants with acute tubular necrosis. Acute rejection was characterized by slight and chronic rejection by marked accumulation. Canine Studies
There was no evidence of radiocolloid accumulation within the renal transplants of the 3 control autografted
Table III: Dog No.
1
2
4
5
6
Graft "Vascular" Transit of TSC
1 2
0 0
+ + + +
4 1 2 3
2 3
2 3 3 4
5 6 2 4
+ + 0 0
+ + + + + + + + +0 +
1
0 0 0
2
0
3
0 0
5 7
Serial Examinations of Seven Allografted Dogs Graft TSC Accu m ulation
3
4
July 1975
dogs at any time from the second to the seventh postgrafting day for a total of 13 examinations. All studies demonstrated a vascular transit phase of 99mTc sulfur colloid and all grafts were normal on pathological examination (Table II). Serial examinations of 4 of the allografted nephrectomized dogs [Dogs 1-4 (Table III)] whose grafts demonstrated uncomplicated acute rejection on pathological examination, exhibited radiocolloid accumulation in the transplant beginning on the second or third post-grafting day. Graft vascular transit of 99mTc sulfur colloid was consistently demonstrated in each examination. Two of the allografted dogs [Dogs 5 and 6] initially showed radiocolloid accumulation followed by absent accumulation, at which time graft vascular transit of 99rntc sulfur colloid could not be demonstrated. Pathological examination revealed graft rejection and anemic necrosis in Dog 5 and graft rejection, necrosis, and renal vein thrombosis in Dog 6. In Dog 7, graft accumulation and graft vascular transit of 99mTc sulfur colloid could not be demonstrated at any time, indicating severely impaired transplant vascularity already present on the first post-grafting day. Pathological examination revealed transplant necrosis secondary to renal artery and vein thrombosis. Gross autoradiographs of the renal transplants of those dogs which showed uncomplicated rejection at the time of sacrifice (Fig. 4) presented an outline of the larger intrarenal vasculature ··mcluding interlobar, arcuate, and interlobular vessels. Grossly visible radioactive thrombi were seen focally in interlobar vessels, subcapsularly, and at the site of the surgical anastomosis at the transplant hilus. Microscopically, radioactivity was concentrated in glomerular fibrin deposits and in areas
Days Post-Grafti ng
4 3
AND OTHERS
Pathology at Sacrifice
Acute rejection
+
+ + + + + + + + + +
Acute rejection
Acute rejection Acute rejection Acute rejection, anemic necrosis
0
+ 0 0
a 0 0 0
Acute rejection, hemorrhagic necrosis & renal vein thrombosis Marked anemic necrosis, renal artery and vein thrombosis
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99mTC SULFUR COLLOID ACCUMULATION IN REJECTING RENAL TRANSPLANTS
of vasculitis associated with endothelial proliferation and fibrin thrombosis (Fig. 5). No radioactivity was found in tubular lumina, in tubular epithelial cells or in interstitial connective tissue and inflammatory infiltrate.
DISCUSSION The recognition of renal transplant rejection, particularly in the immediate post-grafting period, is often difficult. Clinical and laboratory evaluation frequently offers little certitude of pathophysiologic events taking place in the transplant. Clinical diagnosis is further clouded by the frequency of acute tubular necrosis following cadaver graft transplantation (15). In addition, renal artery thrombosis, ureteric obstruction, or intercurrent septicemia may clinically mimic acute rejection (16, 17). From the therapeutic and prognostic standpoint, it is important to differentiate acute rejection from acute tubular necrosis and renal artery thrombosis in the early post-grafting period and to differentiate acute from chronic rejection in long-term surviving grafts (18, 19). Most radioagents have not demonstrated a high degree of reliability in diagnosing renal transplant rejection. Many radiopharmaceuticals, including radioiodinated 169 Yb-EDTA or -DTPA complexes, radioxe· Hippuran, non, radiomercury-Iabeled chlormerodrin, 113mln, 99mT C pertechnetate, or radioiodinated fibrinogen, have been used to demonstrate specific transplant functions. The utilization of two radioagents to assess post-renal transplant complications, particularly rejection, has been favored by many investigators (1-8). Sequential dual isotope renography with 131 1Hippuran and 99mTc pertechnetate provides a method of evaluating transplant tubular function and transplant vascularity. Certain pattern abnormalities favor either rejection or acute tubular necrosis but the diagnostic accuracy is not at a desirable level (8). 131 1or 1251-labeled fibrinogen appears to be the primary agent specific for renal transplant rejection. Its general use in the diagnosis of renal transplant rejection however has been hampered by the potential hazard of serum hepatitis in man, the necessity of a 24-hour delay following administration for optimal imaging, the narrow range of normal-to-abnormal per cent of transplant uptake, and poor imaging qualities (20, 21). In the present study, a simple reproducible technique for the diagnosis of renal transplant rejection is presented. Essentially, only those renal transplants undergoing either acute or chronic rejection accumulate 99mTc sulfur colloid. In patients with normally functioning renal transplants or acute tubular necrosis, radiocolloid is not accumulated within the renal transplant. Care must be exercised in order to establish the circulatory status of the transplant since in instances of impaired graft vascularity, the delivery of the radiocolloid is likewise impaired. The determination of graft vascular transit of 99mrc sulfur colloid or, alternatively, transplant perfusion with 99mT C pertechnetate provides information as to the circulatory integrity of the graft, thus separating
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Nuclear Medicine
functioning transplants from those without function in cases without radiocolloid accumulation. Except for one instance, all cases of chronic rejection exhibited slight to moderate functional impairment and radiocolloid was accumulated more prominently than in transplants undergoing acute rejection at the time of examination. We have postulated that the generally marked interstitial edema and inflammatory infiltrate characteristic of acute rejection-, which are minimal in chronic rejection (22), cause additional vascular compromise and thus lead to less radiocolloid accumulation during acute as compared to chronic rejection. Assuming that the colloidal deposit in the usual sites, such as the liver, spleen and bone marrow, remains unchanged, a fine balance between functional renal vasculature and accumulation sites probably determines the amount of radiocolloid accumulation in acutely and chronically rejecting transplants. This hypothesis is further supported by canine studies. The vascular and glomerular deposit of radioactivity in fibrin thrombosis demonstrated autoradiographically in the hyperacute rejecting canine renal transplants suggests that radiocolloid is trapped within the network of forming fibrin thrombosis. In rejection, the formation of intravascular fibrin thrombosis, thrombolysis or organization is a continuous dynamic process and its net effect depends on the cellular and humeral immune state of the graft recipient (23). As demonstrated in canine transplants, graft vascular transit depends on functional extra- and intrarenal vascularity, and graft radiocolloid accumulation depends on effective vascular transit of 99mrc sulfur colloid and active intrarenal vascular transplant thrombosis.
SUMMARY The accumulation of 99mTc sulfur colloid by renal transplants signals rejection and continues as long as the vascular supply is not severely compromised. Acute rejection is represented by slight radiocolloid accumulation, and chronic rejection by marked accumulation when compared to bone marrow activity. Necrotic transplants in acute rejection and those fibrosed secondary to chronic rejection do not accumulate 99mrc sulfur colloid. In a canine transplant model, vascular transit and graft accumulation of radiocolloid was not demonstrated with graft necrosis following hyperacute rejection or when renal artery thrombosis was a post-grafting complication. Radioautographic studies of hyperacutely rejecting canine grafts demonstrated 99mTc sulfur colloid radioactivity trapped in areas of intravascular and glomerular fibrin thrombosis.
REFERENCES 1. Blaufox MD, Merrill JP: Evaluation of renal transplant function by iodohippurate sodium 1-131. JAMA 202:575-578 13 Nov 1967 2.
'
Gedgaudas E, White RI Jr, Loken MK: Radiology in renal transplantation. Radiol Clin N Am 10:529-544, Dec 1972
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3. HOr G. Pabst HW. Pfeifer KJ. et al: Radionuclides in renal transplantation. J Nucl Med 13:795-800, Nov 1972 4. Staab EV, Hopkins J. Patton DO, et al: The use of radionuclide studies in the prediction of function in renal failure. Radiology 106:141-146, Jan 1973 5. Weiss ER. Blahd WH, Winston MA, et al: Scintillation camera in the evaluation of renal transplants. J Nucl Med 11:69-77, Feb 1970 6. Staab EV, Whittier F, Patton DO, et al: Early evaluation of cadaver renal allotransplant by means of radionuclide imaging. Radiology 106:147-151, Jan 1973 7. Rosenthal L, Mangel R. Lisbona R, et al: Diagnostic applications of radiopertechnetate and radiohippurate imaging in postrenal transplant complications. Radiology 111:347-358, May 1974 8. Solanc-Georqe EA, Anderson CA. Codd JE, et al: Differentiation of acute tubular necrosis and rejection by dual radionuclide renography. [In] Proceedings of the Clinical Dialysis and Transplant Forum, Vol III, Schreiner GE, Diamond LK, Ryan JP, ed. Washington, D.C., Georgetown University Press, 1974, pp 77-84 9. George EA, Codd JE, Newton WT, et al: Visualization of rejecting renal transplants with 99mTc sulfur colloid (TSC). J Nucl Med 15:493. 1974 (abst) . 10. Solaric-George EA, Fletcher JW, Newton WT, et al: Renal accumulation of 99mTc sulfur colloid in transplant rejection. Radiology 111:465-466, May 1974 11. George EA, Newton WT, Henry RE. et al: Triple radioagent assessment of renal transplant rejection. (In preparation) 12. Donati RM, Berman AR, Jervis HR, et al: Absorption of iron following x-irradiation of the exteriorized small intestine. Proc Soc Exp Bioi Moo 130:822-827, Mar 1969 13. Tilden RL, Jackson J Jr, Enneking WF, et al: 99mTc_poly_ phosphate: histological localization in human femurs by autoradiography. J Nucl Med 14:576-578, Aug 1973 14. Harlan WR Jr, Holden KR, Williams GM. et al: Proteinuria
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and nephrotic syndrome associated with chronic rejection of kidney transplants. New Eng J Med 277:769-776, 12 Oct 1967 15. Branch RA, Coles GA, Eynon A, et al: The use of radioactive hippuran in the management of cadaveric renal transplants. Br J Radiol 44:697-704, Sep 1971 16. Figueroa JE, Maxfield WS, Batson HM Jr, et al: Radioisotope renal function studies in human renal allografts: value in the differential diagnosis of oliguria in the presence of obstructive disease with and without urinary extravasation. J Urol 100: 104-1 08, Aug 1968 17. Malek GH, Uehling DT, Daouk AA, et al: Urological complications of renal transplantation. J Urol 109: 173-176, Feb 1973 18. Simmons RL, Khellstrand CM, Najarian JS: Transplantation: Kidney, Section II: Technique, Complication and Results. Philadelphia, Lea and Febinger, 1972, pp 462-480 19. Williams GM, Lee HM, Weymouth RF, et al: Studies in hyperacute and chronic renal homograft rejection in man. Surgery 62:204-212, Jul1967 20. Winston MA, Weiss ER, 81ahd WH, et al: Use of 131-I-fibrinogen in detection of renal transplant rejection. Invest Urol 9: 119-123, Sep 1971 21. Howard RJ, Sutherland DER, Najarian JS: Detection of renal allograft rejection with (125-1) fibrinogen. J Surg Res 15:251254, Oct 1973 22. Busch GJ, Galvanek EG, Reynolds ES Jr: Human renal allografts. Analysis of lesions in long-term survivors. Hum Pathol 2: 253-298, Jun 1971 23. Balch CM, Diethelm AG: The pathophysiology of renal allograft rejection: a collective review. J Surg Res 12:350-377, May 1972 Nuclear Medicine Service (172-JC) St. Louis Veterans Administration Hospital S1. Louis, Mo. 63125
