References 1.
2.
3.
Braffman BH, Bilaniuk LT, Naidich TP, et al. MR imaging of tuberous sclerosis: pathogenesis of this phakomatosis, use of gadopentetate dimeglumine, and literature review. Radiology 1992; 183:227238. Wilms G, van Wijek E, Smet MH, BrocherJM. Gyriform calcifications in tuberous sclerosis simulating the appearance of Sturge-Weber disease. AJNR 1992; 13:295-298. Hilal 5K, Solomon GE, Gold AP, Carter S. Primary cerebral arterial occlusive disease in children. II. Neurocutaneous syndromes. Radiology 1971; 99:87-93.
.
Pulmonary Embolism the Lower Extremity
during
Compression
US of
From: Hector Ferrab, MD, Joseph Hunter, MD, and Jams Department of Radiology, 420
Delaware
Editor: We read,
Street,
with
Southeast,
great
monary
embolism
Minneapolis,
interest,
issue of Radiology
1992
W. Yedlicka, Jr, MD, David Gissel Letoumeau, MD University of Minnesota
(1).
occurred
the article Perlin
MN
by Perlin
describes
during
a case
compression
(US) of the lower extremity and states this has not previously been reported
that,
W.
55455
in the July in which
pul-
ultrasound to his
knowledge,
in the radiology biterature. However, a very similar case has been described previously in the radiology literature (2). In this case, initial sonographic images demonstrated an incompressible intraluminal thrombus within the right common femoral vein; no venous flow was detected with Doppler US. Repeat compression US performed 2 minutes later showed a fully compressible femorab vein. Doppler US examination revealed normal spectra waveforms. Ventilation-perfusion scintigraphy performed after this event demonstrated multiple segmental, unmatched perfusion defects. The chest radiograph was normal. Although the actual migration of the clot was not witnessed with real-time US, it was thought to have occurred, as a result of the unequivocal nature of both the sonographie and seintigraphic studies. At that time, it was believed that dislodgment of the thrombus
was
directly
related
to attempted
luminal
compression
a.
of
the vein during sonography for the diagnosis of deep venous thrombosis. The exact cause or mechanism of dislodgment was not elucidated. We agree with Perlin’s recommendation to perform Doppler interrogation immediately after identifying a noncompressible or partially incompressible vein; this would minimize errors in Doppler sampling in the rare event of thrombus dislodgment. We hope that this additional informalion will be of some value.
References 1.
Perlin
S.
Pulmonary
embolism
during
compression
US of the
lower
2.
U
extremity. Radiology 1992; 184:165-166. Yedlicka JW, Hunter DW, Letourneau JG. Pulmonary embolism after femoral vein compression during sonography: case report. Semin Intervent Radiol 1990; 7:24-26.
Fat-Suppression
MR
Arthrography
of the
Shoulder From:
Russell C. Fritz, MD, and David W. Stoller, MD California Advanced Imaging 3440 California Street, San Francisco, CA 94118
Coronal oblique Ti-weighted MR images (repetition msec; echo time, 20 msec) obtained without (a) and suppression. (a) High-signal-intensity be mistaken for contrast material, nosis of a complete rotator cuff
throughout the image trast material remains
reveals confined
time,
with
600
(b) fat
peribursal fat (arrows) leading to a false-positive tear. (b) Effective suppression
that the high-signal-intensity to the glenohumeral joint
could diagof fat
conspace.
Editor: In the February 1992 issue of Radiology, Hodler et al (1) reported their experience with magnetic resonance (MR) arthrography in the evaluation of the rotator cuff. They reported four false-positive diagnoses of full-thickness rotator cuff tears with MR arthrography in patients whose rotator cuff was in-
614
Radiology
#{149}
tact or partially torn at arthroscopy. In three of positive cases, the peribursal fat was mistakenly represent contrast medium that had leaked into toid-subacromial bursa. They suggest that these have been avoided with a combined readout of
the four falsethought to the subdelerrors could the standard
November
1992
2.
3.
Braffman BH, Bilaniuk LT, Naidich TP, et al. MR imaging of tuberous sclerosis: pathogenesis of this phakomatosis, use of gadopentetate dimeglumine, and literature review. Radiology 1992; 183:227238. Wilms G, van Wijek E, Smet MH, BrocherJM. Gyriform calcifications in tuberous sclerosis simulating the appearance of Sturge-Weber disease. AJNR 1992; 13:295-298. Hilal 5K, Solomon GE, Gold AP, Carter S. Primary cerebral arterial occlusive disease in children. II. Neurocutaneous syndromes. Radiology 1971; 99:87-93.
.
Pulmonary Embolism the Lower Extremity
during
Compression
US of
From: Hector Ferrab, MD, Joseph Hunter, MD, and Jams Department of Radiology, 420
Delaware
Editor: We read,
Street,
with
Southeast,
great
monary
embolism
Minneapolis,
interest,
issue of Radiology
1992
W. Yedlicka, Jr, MD, David Gissel Letoumeau, MD University of Minnesota
(1).
occurred
the article Perlin
MN
by Perlin
describes
during
a case
compression
(US) of the lower extremity and states this has not previously been reported
that,
W.
55455
in the July in which
pul-
ultrasound to his
knowledge,
in the radiology biterature. However, a very similar case has been described previously in the radiology literature (2). In this case, initial sonographic images demonstrated an incompressible intraluminal thrombus within the right common femoral vein; no venous flow was detected with Doppler US. Repeat compression US performed 2 minutes later showed a fully compressible femorab vein. Doppler US examination revealed normal spectra waveforms. Ventilation-perfusion scintigraphy performed after this event demonstrated multiple segmental, unmatched perfusion defects. The chest radiograph was normal. Although the actual migration of the clot was not witnessed with real-time US, it was thought to have occurred, as a result of the unequivocal nature of both the sonographie and seintigraphic studies. At that time, it was believed that dislodgment of the thrombus
was
directly
related
to attempted
luminal
compression
a.
of
the vein during sonography for the diagnosis of deep venous thrombosis. The exact cause or mechanism of dislodgment was not elucidated. We agree with Perlin’s recommendation to perform Doppler interrogation immediately after identifying a noncompressible or partially incompressible vein; this would minimize errors in Doppler sampling in the rare event of thrombus dislodgment. We hope that this additional informalion will be of some value.
References 1.
Perlin
S.
Pulmonary
embolism
during
compression
US of the
lower
2.
U
extremity. Radiology 1992; 184:165-166. Yedlicka JW, Hunter DW, Letourneau JG. Pulmonary embolism after femoral vein compression during sonography: case report. Semin Intervent Radiol 1990; 7:24-26.
Fat-Suppression
MR
Arthrography
of the
Shoulder From:
Russell C. Fritz, MD, and David W. Stoller, MD California Advanced Imaging 3440 California Street, San Francisco, CA 94118
Coronal oblique Ti-weighted MR images (repetition msec; echo time, 20 msec) obtained without (a) and suppression. (a) High-signal-intensity be mistaken for contrast material, nosis of a complete rotator cuff
throughout the image trast material remains
reveals confined
time,
with
600
(b) fat
peribursal fat (arrows) leading to a false-positive tear. (b) Effective suppression
that the high-signal-intensity to the glenohumeral joint
could diagof fat
conspace.
Editor: In the February 1992 issue of Radiology, Hodler et al (1) reported their experience with magnetic resonance (MR) arthrography in the evaluation of the rotator cuff. They reported four false-positive diagnoses of full-thickness rotator cuff tears with MR arthrography in patients whose rotator cuff was in-
614
Radiology
#{149}
tact or partially torn at arthroscopy. In three of positive cases, the peribursal fat was mistakenly represent contrast medium that had leaked into toid-subacromial bursa. They suggest that these have been avoided with a combined readout of
the four falsethought to the subdelerrors could the standard
November
1992
