Kazuro
Sugimura,
MD
#{149} Bernadette
Postirradiation Assessment
M. Carrington,
MD
#{149} Jeanne
M. Quivey,
Changes in the with MR Imaging’
T
Magnetic resonance (MR) imaging features of pelvic radiation change were assessed in 51 patients and were correlated with tumor and critical tissue radiation dose, time after treatment, and clinical symptoms. The severity of MR tissue changes was graded. Radiation tissue toxicity increased significantly when the dose exceeded 4,500 cGy, with the incidence of marked bladder and rectal changes rising from 8% to 51% and from 24% to 48%, respectively. Similar dose-related changes were seen in other pelvic organs. All grades of tissue change were seen in the bladder and rectum regardless of the time from start of therapy. All patients who exhibited clinical grade 2 or 3 bladder and rectal changes showed moderate or severe changes on MR images. In asymptomatic patients, minimal MR changes were seen in the bladder (47%) and in the rectum (33%). The accuracy of MR imaging in differentiating between radiation damage and residual/recurrent tumor varied with the primary tumor site, being excellent for recurrent cervical cancer and less so for rectal carcinoma.
of treatment is precise delivuniform tumor dose, but the normal tissue cannot be shielded during radiation and tissue changes may re-
sult. Acute to radiation
and chronic changes therapy are typically
due
seen in rapidly renewing tissue, as that in the rectum and bladder The radiation injury is dose-dependent,
but
great
exists in the toxicity and
individual
symptoms (2). This study was
such (1).
of tissue clinical
emphasis
on
designed
the
imspe-
bladder
in differentiating
ation tissue changes recurrent tumor. MATERIALS
Index
terms: neoplasms,
33.1214
MR studies,
87.1214
844.1214 #{149} Rectum, neoplasms, 75.32 Uterine neoplasms, na,
MR studies,
postirradi-
from
AND
#{149}
py
neoplasms,
855.32
were
residual
or
#{149} Vulva,
Rectum, 33.1214 #{149} Vagi-
#{149}
#{149}
assessed
METHODS
1984
and
retrospectively.
study.
The
were
rectal
primary
1990; 175:805-813
tumors
and anal
tients), sigmoid tients), bladder prostate gland and gynecologic
neoplasms,
89.32
Radiology
January
March
1989
Fifty-one
irradiated
carcinoma
carcinoma carcinoma carcinoma neoplasms
carcinoma,
gland carcinoma, in one patient
Imaging
carcinoma
vaginal
and each).
cervical
Techniques performed with a 0.35-T Diasonics, Milpitas, Calif) with a i.5-T unit (Signa;
GE Medical Systems, Milwaukee) A spin-echo (SE) multisection
in 12. imaging
was used in all 51 examinathe 0.35-T unit, an SE 500/15-30 time msec/echo time msec)
was considered
Ti-weighted,
image
was
and
considered
On the 1.5-T unit,
800/20 image was considered Ti-weighted, and an SE TR 2,000/70-80 image was considered T2-weighted. At both field strengths, Ti- and T2-weighted images in the transverse plane and T2-weighted images in the sagittal plane were obtained every
patient.
Eleven
also obtained
Patient
examinations
in the coronal
Record
plane.
Review
(iO pa-
(three pa(one patient), (two patients), (cervical cam-
were
reviewed
tumor. Rec-
to document
ation dose to the primary tumor cent critical tissue (eg, bladder, perirectal adipose tissue, uterus,
gland,
was
perivesical
adipose
the
I From
the
Departments
University
Radiology,
Shimane
ceived cepted C
September December
RSNA,
1990
of Radiology
of California, Medical
13, 1989;
28. Address
(Box
0628)
San Francisco,
University,
revision
reprint
Japan
requested
requests
(B.M.C.,
H.H.)
and
Radiation
tissue,
pelvic
wall muscle, and bone marrow of the sacrum) at the time the MR study was obtamed. Because of the inclusion of different primary tumors in this analysis, the tumor dose and dose to adjacent normal tissues varied, as did the technique of madiation delivery. External beam radiation
was administered voltage techniques, per
fraction
week.
use
Oncology
San Francisco, CA 94143, and the Department of (KS.). From the 1989 RSNA annual meeting. ReNovember
20; revision
received
December
madi-
and adjarectum, prostate
When
with the use delivering
at a rate
of five
multiport
of mega180 cGy
fractions
techniques
of isodose
therapy
dose
curves. plans
Similarly, were
reviewed
per
were
used, estimation of the dose to the and adjacent tissues was facilitated (J.M.Q.),
T2-
an SE 600-
The following clinical information obtained from the medical records: 1. Site and extent of the primary 2. Radiation dose and technique.
patients (10 men and 41 women) aged 3080 years (mean, 52.7 years) fulfilled the criteria and have been included in this
MR studies,
#{149} Prostate,
MR studies, 75.32 #{149} Spine, MR studies, MR studies, 854.32
between
MD
vulvan
and
Studies were system (MT/S; in 39 cases and
in
Consecutive patients who underwent pelvic MR imaging after radiation thema-
757.1214
MR
ords
757.32 #{149} Bladder neoplasms, 83.1214 #{149}Bone marrow, MR stud#{149} Colon, neoplasms, 75.32 #{149} Pelvis,
MR studies, ies,
Anus,
Bartholin melanoma
were
Patients
Anus,
patients,
weighted.
to evalu-
urinary
Hricak,
in 27 patients,
five
image
and rectum. The MR findings were correlated with radiation dose, time factors, and clinical symptoms. Also evaluated was the usefulness of MR imaging
in
an SE 2,000/60
ate the magnetic resonance (MR) aging features of postirradiation changes in all pelvic tissue, with cial
cinoma
technique tions. On (repetition
variation
development subsequent
#{149} Hedvig
Pelvis:
HE primary choice of therapy for many pelvic cancers is radiation.
The aim ery of a adjacent completely therapy,
MD
tumor by the
brachyfor pa-
22; ac-
to H.H. Abbreviation:
SE
=
spin
echo.
805
Figures 1, 2. (1) MR grade lA radiation-induced change in bladder, acute phase. SE 2,000/60 sagittal MR image obtained at 0.35 T. There
is high
signal
intensity
localized
to
the mucosa of the tnigone (arrowhead). Bladder muscle demonstrates normal low signal intensity. Within the rectum low-signal-intensity
wall
can
be
differentiated
from
high-
er-signal-intensity
submucosa. Arrow mdicates anorectal junction. (2) MR grade lB madiation-induced change in bladder, subacute phase. SE 2,000/60 sagittal MR image obtamed at 0.35 T. Inner high-signal-intensity
region
(arrow)
extends
Heterogeneous (1) is residual
beyond
the trigone.
high-signal-intensity
mass
cervical
carcinoma.
1.
2.
who received interstitial implants and intnacavitary applications, and the dose to tumor and adjacent critical organs was estimated. tients
3. Adjunct therapy.
administration
of chemo-
4. Time factor. The time after initiation of treatment was recorded and classified as follows: early acute (during the first 3 weeks of treatment), acute (3 weeks to 3 months
apy),
after
institution
subacute
tion of therapy), 12 months after (3,4). 5.
of radiation
(3-12
Clinical
months
them-
institu-
and chronic (more than institution of therapy)
symptoms.
tal symptoms were scored
after
Bladder
and
nec-
at the time of the MR study with use of a modified Ra-
diumhemmet grading system (Table 1) (4,5). Only hematunia, rectal bleeding, and fistulas were scored for the purpose of this analysis, so that objective clinical findings could be correlated with symptoms. 6. Histologic findings. When biopsy or surgical resection was performed, the histologic and MR findings were correlated.
MR
Image
Data
a.
Figure
3. MR grade 2 radiation-induced change in bladder, chronic phase. Transaxial MR images obtained at 0.35 T. B bladder, R rectum, * presacral space. (a) On SE 500/15 Tiweighted image, the bladder wall (straight arrow) is thickened, the perirectal fascia (curved arrow) is thickened, and the presacral space is widened. (b) On SE 2,000/60 T2-weighted image, the outer portion of the bladder wall demonstrates high signal intensity, while the inner part (arrowhead) demonstrates low signal intensity. The obturator intemnus muscle (amrow) shows abnormal high signal intensity. The perivesical and perirectal fat demonstrates abnormal low-signal-intensity stranding on a; the intensity is increased on b, although it is still
less
than
nal
intensity
that
of fat.
A similar
signal-intensity
change
is seen
in the
presacral
space.
Analysis
The MR images were reviewed knowledge of the radiation dose
without or the
clinical
and histologic findings. Changes at MR imaging in the urinary bladder, rectum, and anus were categorized with use of the Radiumhemmet grading system (4,5) as a guideline (Table 2). seen
Urinary
signal
bladder.-On
intensity
of the
MR images, urinary
the
bladder
was considered normal (grade 0) when the bladder wall exhibited homogeneous medium signal intensity on Ti-weighted images and decreased signal intensity on T2-weighted images (6). Although blad-
den wall thickness changes with the degree of bladder distention, it should not be greater than 5 mm. Grade 1 and grade 2 bladder abnormalities are illustrated in Figures 1-3. One patient underwent cystectomy after radiation therapy. Themefore, only 50 examinations were included in the analysis. Anus and rectum-Depending on the site and extent of the primary tumor, a madiation port could include the rectum, the anus, or both the rectum and the anus. We found no description of the MR sig-
806
Radiology
#{149}
of the
normal
rectum
and
anus in the literature, and such a description is therefore presented. The rectum extends from the upper border of 5-3 to the
perineum
(7).
The
upper
part
is
termed the ampulla of the rectum, and the lower part is termed the anal canal (7). The ampulla is of wide caliber, its size depending on its state of filling and the contractility
wall. wall
of the
smooth
The normal thickness or the distended rectal
muscle
of its
of the anal wall should
not exceed 6 mm (8). smooth muscle covers of the rectum and is and posteriorly. The anal canal is thicker ampulla and contains
layer
(internal
Longitudinal the entire surface thickened anteriorly muscular wall of the than that of the rectal a thickened circular
anal sphincter
muscle)
and
an outer longitudinal layer (the muscularis extemna), which in its distal portion is interleaved with the skeletal muscle fibers from the levatom ani. On T2-weighted images obtained in the region of the
June
1990
5.
4.
6.
Figures 4-6. (4) Normal anal canal. Transaxial SE 2,000/60 MR image obtained at 1.5 T depicts outer muscular layer of low signal intensity, best seen anteriorly (arrow), where there is localized thickening of the longitudinal smooth-muscle component. Medial to the outer muscle layer, the submucosa is seen as a high-signal-intensity ring, followed by an inner low-signal-intensity ring (arrowhead). A central high-signal-intensity
region
is also
seen.
(5)
Normal
anorectal
junction,
slightly
distended.
Transaxial
SE
2,000/60
MR
image
obtained
at
1.5
picts outer muscle layer (white arrow) and higher-signal-intensity submucosa. Inner low-signal-intensity ring cannot be identified, blends with the low signal intensity of intmaluminal air. Chemical shift artifact (black arrow) should not be confused with muscle (6) MR grade 1 radiation-induced change in the anal canal, acute phase. Transaxial SE 2,000/60 MR image obtained at 1.5 T depicts thickness of submucosa (arrow). Outer muscle layer and inner low-signal-intensity ring are preserved.
Table 2 MR Grading
T de-
as it layer. increased
System Criteria Tumor
Type
Recurrence
of
Abnormality
Grade
Bladder
0
Grade
1
Grade
Wall thickness
Sugimura,
MD
#{149} Bernadette
Postirradiation Assessment
M. Carrington,
MD
#{149} Jeanne
M. Quivey,
Changes in the with MR Imaging’
T
Magnetic resonance (MR) imaging features of pelvic radiation change were assessed in 51 patients and were correlated with tumor and critical tissue radiation dose, time after treatment, and clinical symptoms. The severity of MR tissue changes was graded. Radiation tissue toxicity increased significantly when the dose exceeded 4,500 cGy, with the incidence of marked bladder and rectal changes rising from 8% to 51% and from 24% to 48%, respectively. Similar dose-related changes were seen in other pelvic organs. All grades of tissue change were seen in the bladder and rectum regardless of the time from start of therapy. All patients who exhibited clinical grade 2 or 3 bladder and rectal changes showed moderate or severe changes on MR images. In asymptomatic patients, minimal MR changes were seen in the bladder (47%) and in the rectum (33%). The accuracy of MR imaging in differentiating between radiation damage and residual/recurrent tumor varied with the primary tumor site, being excellent for recurrent cervical cancer and less so for rectal carcinoma.
of treatment is precise delivuniform tumor dose, but the normal tissue cannot be shielded during radiation and tissue changes may re-
sult. Acute to radiation
and chronic changes therapy are typically
due
seen in rapidly renewing tissue, as that in the rectum and bladder The radiation injury is dose-dependent,
but
great
exists in the toxicity and
individual
symptoms (2). This study was
such (1).
of tissue clinical
emphasis
on
designed
the
imspe-
bladder
in differentiating
ation tissue changes recurrent tumor. MATERIALS
Index
terms: neoplasms,
33.1214
MR studies,
87.1214
844.1214 #{149} Rectum, neoplasms, 75.32 Uterine neoplasms, na,
MR studies,
postirradi-
from
AND
#{149}
py
neoplasms,
855.32
were
residual
or
#{149} Vulva,
Rectum, 33.1214 #{149} Vagi-
#{149}
#{149}
assessed
METHODS
1984
and
retrospectively.
study.
The
were
rectal
primary
1990; 175:805-813
tumors
and anal
tients), sigmoid tients), bladder prostate gland and gynecologic
neoplasms,
89.32
Radiology
January
March
1989
Fifty-one
irradiated
carcinoma
carcinoma carcinoma carcinoma neoplasms
carcinoma,
gland carcinoma, in one patient
Imaging
carcinoma
vaginal
and each).
cervical
Techniques performed with a 0.35-T Diasonics, Milpitas, Calif) with a i.5-T unit (Signa;
GE Medical Systems, Milwaukee) A spin-echo (SE) multisection
in 12. imaging
was used in all 51 examinathe 0.35-T unit, an SE 500/15-30 time msec/echo time msec)
was considered
Ti-weighted,
image
was
and
considered
On the 1.5-T unit,
800/20 image was considered Ti-weighted, and an SE TR 2,000/70-80 image was considered T2-weighted. At both field strengths, Ti- and T2-weighted images in the transverse plane and T2-weighted images in the sagittal plane were obtained every
patient.
Eleven
also obtained
Patient
examinations
in the coronal
Record
plane.
Review
(iO pa-
(three pa(one patient), (two patients), (cervical cam-
were
reviewed
tumor. Rec-
to document
ation dose to the primary tumor cent critical tissue (eg, bladder, perirectal adipose tissue, uterus,
gland,
was
perivesical
adipose
the
I From
the
Departments
University
Radiology,
Shimane
ceived cepted C
September December
RSNA,
1990
of Radiology
of California, Medical
13, 1989;
28. Address
(Box
0628)
San Francisco,
University,
revision
reprint
Japan
requested
requests
(B.M.C.,
H.H.)
and
Radiation
tissue,
pelvic
wall muscle, and bone marrow of the sacrum) at the time the MR study was obtamed. Because of the inclusion of different primary tumors in this analysis, the tumor dose and dose to adjacent normal tissues varied, as did the technique of madiation delivery. External beam radiation
was administered voltage techniques, per
fraction
week.
use
Oncology
San Francisco, CA 94143, and the Department of (KS.). From the 1989 RSNA annual meeting. ReNovember
20; revision
received
December
madi-
and adjarectum, prostate
When
with the use delivering
at a rate
of five
multiport
of mega180 cGy
fractions
techniques
of isodose
therapy
dose
curves. plans
Similarly, were
reviewed
per
were
used, estimation of the dose to the and adjacent tissues was facilitated (J.M.Q.),
T2-
an SE 600-
The following clinical information obtained from the medical records: 1. Site and extent of the primary 2. Radiation dose and technique.
patients (10 men and 41 women) aged 3080 years (mean, 52.7 years) fulfilled the criteria and have been included in this
MR studies,
#{149} Prostate,
MR studies, 75.32 #{149} Spine, MR studies, MR studies, 854.32
between
MD
vulvan
and
Studies were system (MT/S; in 39 cases and
in
Consecutive patients who underwent pelvic MR imaging after radiation thema-
757.1214
MR
ords
757.32 #{149} Bladder neoplasms, 83.1214 #{149}Bone marrow, MR stud#{149} Colon, neoplasms, 75.32 #{149} Pelvis,
MR studies, ies,
Anus,
Bartholin melanoma
were
Patients
Anus,
patients,
weighted.
to evalu-
urinary
Hricak,
in 27 patients,
five
image
and rectum. The MR findings were correlated with radiation dose, time factors, and clinical symptoms. Also evaluated was the usefulness of MR imaging
in
an SE 2,000/60
ate the magnetic resonance (MR) aging features of postirradiation changes in all pelvic tissue, with cial
cinoma
technique tions. On (repetition
variation
development subsequent
#{149} Hedvig
Pelvis:
HE primary choice of therapy for many pelvic cancers is radiation.
The aim ery of a adjacent completely therapy,
MD
tumor by the
brachyfor pa-
22; ac-
to H.H. Abbreviation:
SE
=
spin
echo.
805
Figures 1, 2. (1) MR grade lA radiation-induced change in bladder, acute phase. SE 2,000/60 sagittal MR image obtained at 0.35 T. There
is high
signal
intensity
localized
to
the mucosa of the tnigone (arrowhead). Bladder muscle demonstrates normal low signal intensity. Within the rectum low-signal-intensity
wall
can
be
differentiated
from
high-
er-signal-intensity
submucosa. Arrow mdicates anorectal junction. (2) MR grade lB madiation-induced change in bladder, subacute phase. SE 2,000/60 sagittal MR image obtamed at 0.35 T. Inner high-signal-intensity
region
(arrow)
extends
Heterogeneous (1) is residual
beyond
the trigone.
high-signal-intensity
mass
cervical
carcinoma.
1.
2.
who received interstitial implants and intnacavitary applications, and the dose to tumor and adjacent critical organs was estimated. tients
3. Adjunct therapy.
administration
of chemo-
4. Time factor. The time after initiation of treatment was recorded and classified as follows: early acute (during the first 3 weeks of treatment), acute (3 weeks to 3 months
apy),
after
institution
subacute
tion of therapy), 12 months after (3,4). 5.
of radiation
(3-12
Clinical
months
them-
institu-
and chronic (more than institution of therapy)
symptoms.
tal symptoms were scored
after
Bladder
and
nec-
at the time of the MR study with use of a modified Ra-
diumhemmet grading system (Table 1) (4,5). Only hematunia, rectal bleeding, and fistulas were scored for the purpose of this analysis, so that objective clinical findings could be correlated with symptoms. 6. Histologic findings. When biopsy or surgical resection was performed, the histologic and MR findings were correlated.
MR
Image
Data
a.
Figure
3. MR grade 2 radiation-induced change in bladder, chronic phase. Transaxial MR images obtained at 0.35 T. B bladder, R rectum, * presacral space. (a) On SE 500/15 Tiweighted image, the bladder wall (straight arrow) is thickened, the perirectal fascia (curved arrow) is thickened, and the presacral space is widened. (b) On SE 2,000/60 T2-weighted image, the outer portion of the bladder wall demonstrates high signal intensity, while the inner part (arrowhead) demonstrates low signal intensity. The obturator intemnus muscle (amrow) shows abnormal high signal intensity. The perivesical and perirectal fat demonstrates abnormal low-signal-intensity stranding on a; the intensity is increased on b, although it is still
less
than
nal
intensity
that
of fat.
A similar
signal-intensity
change
is seen
in the
presacral
space.
Analysis
The MR images were reviewed knowledge of the radiation dose
without or the
clinical
and histologic findings. Changes at MR imaging in the urinary bladder, rectum, and anus were categorized with use of the Radiumhemmet grading system (4,5) as a guideline (Table 2). seen
Urinary
signal
bladder.-On
intensity
of the
MR images, urinary
the
bladder
was considered normal (grade 0) when the bladder wall exhibited homogeneous medium signal intensity on Ti-weighted images and decreased signal intensity on T2-weighted images (6). Although blad-
den wall thickness changes with the degree of bladder distention, it should not be greater than 5 mm. Grade 1 and grade 2 bladder abnormalities are illustrated in Figures 1-3. One patient underwent cystectomy after radiation therapy. Themefore, only 50 examinations were included in the analysis. Anus and rectum-Depending on the site and extent of the primary tumor, a madiation port could include the rectum, the anus, or both the rectum and the anus. We found no description of the MR sig-
806
Radiology
#{149}
of the
normal
rectum
and
anus in the literature, and such a description is therefore presented. The rectum extends from the upper border of 5-3 to the
perineum
(7).
The
upper
part
is
termed the ampulla of the rectum, and the lower part is termed the anal canal (7). The ampulla is of wide caliber, its size depending on its state of filling and the contractility
wall. wall
of the
smooth
The normal thickness or the distended rectal
muscle
of its
of the anal wall should
not exceed 6 mm (8). smooth muscle covers of the rectum and is and posteriorly. The anal canal is thicker ampulla and contains
layer
(internal
Longitudinal the entire surface thickened anteriorly muscular wall of the than that of the rectal a thickened circular
anal sphincter
muscle)
and
an outer longitudinal layer (the muscularis extemna), which in its distal portion is interleaved with the skeletal muscle fibers from the levatom ani. On T2-weighted images obtained in the region of the
June
1990
5.
4.
6.
Figures 4-6. (4) Normal anal canal. Transaxial SE 2,000/60 MR image obtained at 1.5 T depicts outer muscular layer of low signal intensity, best seen anteriorly (arrow), where there is localized thickening of the longitudinal smooth-muscle component. Medial to the outer muscle layer, the submucosa is seen as a high-signal-intensity ring, followed by an inner low-signal-intensity ring (arrowhead). A central high-signal-intensity
region
is also
seen.
(5)
Normal
anorectal
junction,
slightly
distended.
Transaxial
SE
2,000/60
MR
image
obtained
at
1.5
picts outer muscle layer (white arrow) and higher-signal-intensity submucosa. Inner low-signal-intensity ring cannot be identified, blends with the low signal intensity of intmaluminal air. Chemical shift artifact (black arrow) should not be confused with muscle (6) MR grade 1 radiation-induced change in the anal canal, acute phase. Transaxial SE 2,000/60 MR image obtained at 1.5 T depicts thickness of submucosa (arrow). Outer muscle layer and inner low-signal-intensity ring are preserved.
Table 2 MR Grading
T de-
as it layer. increased
System Criteria Tumor
Type
Recurrence
of
Abnormality
Grade
Bladder
0
Grade
1
Grade
Wall thickness
