ABSTRACTS
Vo[. 2, No. 12, December 1995
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Computed Tomographic Contrast Lymphography with WIN 8833 in Melanoma in Bearing Miniature Swine Bhaskara K. Rao, M.D., M.S., Ji Bin Uu, M.D., Patrick Haley, Ph.D., David Johnson, Ph.D., Adele Vessey, Ph.D. Thomas Jefferson University Hospital, Sterling Winthrop, Inc.
Purpose: This study aims to evaluate the efficacy of a new subcutaneously injectable iodine based nanoparticulate material (WIN 8833) for opacifying regional nodes in control swine and detecting metastases in melanoma bearing swine. Materials and methods: Sterile WIN 8833 (0.7 to 6 rat in devided doses) was subcutaneously injected in the limbs to a normal swine and five m e l a n o m a bearing m i n i a t u r e Sinclair swine a r o u n d the tumor site. Serial CT and radiographs of the d r a i n i n g regional nodes w e r e obtained 1.5 to 1008 hrs post-injection. Histopathologic study (HP) of the excised nodes was performed for presence of metastases. Results: N o r m a l node opacification was optimal at I6-28 hrs on CT and 28-51 hrs on radiographs. Out of 36 nodes examined, 13 (36%) were s h o w n to h a v e metastases by both C T and HP. 16 (44%) w e r e normal by both CT and H P and 7 (19%) a p p e a r e d to be n o r m a l by CT and contained metastases on H P (False negatives). In all but one case, the false negative nodes had less than 10% of the node occupied by tumor. N o false positive nodes were encountered. C o n c l u s i o n : Sterile WIN 8833 suspension was efficaceous for the detection of metastatic nodes in melanoma. An overall correct diagnosis of 81°/o w a s m a d e in the l y m p h nodes examined.
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Double Phase Technetium-99M-Sestamibi Imaging in Hyperparathyroidism Vivian S. Lee, M.D., Ph.D., R.H. Wilkinson, Jr., M.D., G.S. Leight, M.D., A.C. Coogan, M.D. Duke University Medical Center.
Purpose: To evaluate the accuracy of Tc-99m-sestamibi as a single agent in the detection and localization of hyperfunctioning parathyroid tissue in patients who have prior history of neck exploration or who are high surgical risks. Methods: Thirty-eight pafiears underwent double phase Tc-99m-sestamibiimaging, of whom 26 underwent surgery within four months of imaging, and one autopsy after death due to hyperealcemic crisis. Four patients have not undergone surgery because of negative studies; the remaining seven are awaiting or have refused surgery despite positive studies. Indications for imaging in these 27 patients (20 women, 7 men) included prior neck surgery in 14 and increased surgical risk because of age or medical conditions in 13. Planar images of the neck and upper thorax were obtained 10-15 min and 2-3 hours after injection with approximately 25 mCi (925 MBq) 99m-Tcsestamibi. Persistence of tracer on delayed images constituted a positive study. Results: All surgical patients became normoeaicemiepostoperatively. Twenty patients were found to have a single adenoma (including two in the anterior mediastinum), six patients had multiple gland hyperplasia (including one with a fifth gland in the mediastinum), and one a hyperfunctioning forearm transplant. Overall, sestamibi prospectively identified 34/46 (74%) abnormal parathyraid glands- In patients with single adenoma, 20/20 (100%) of the scans accurately localized the glands, while 13/26 (50%) hyperplastie glands were detected. One false positive was found at surgery to represent a sarcoid nodule in the neck. Multiple hyperplasfie glands were difficult to distinguish from abnormal thyroid uptake. No correlation was found between parathyroid hormone levels ~md detection by sestamibi. Conelusions: Preoperative imaging in reoperative hyperparathyroid patients or those at high surgical risk may improve operative success and decrease associated perioperative morbidity. Parathyroid imaging using a single radionuclide agent, sestamibi, is comparable in accuracy to dual tracer seintigraphy and may prove preferable for its simplicity and efficiency. However, loeaiization of hyperplastic glands remains a challenge.
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Evaluation of Infrapopliteal Arteries Using Helical CT Angiography Lloyd E. Heller, M.D., Harry G. Zegel, M.D., Vikram S. Dravid, M.D., Linda A. Kloss, D.O., David B. Freiman, M.D. Presbyterian Medical Center.
P u r p o s e : T o e v a l u a t e t h e a b i l i t y o f h e l i c a l CT a n g i o g r a p h y [HCTA] to demonstrate and characterize infrapopliteal arterial disease. M a t e r i a l s a n d M e t h o d s : 14 s e l e c t e d p a t i e n t s w i t h l o w e r e x t r e m i t y i s c h e m i a , e v i d e n c e d b y c l a u d i c a t i o n o r t i s s u e loss, a d m i t t e d for b y p a s s s u r g e r y w e r e e v a l u a t e d b y HCTA. A r t e r i a l c o n t r a s t was a d m i n i s t e r e d a t a r a t e o f 3 c c . / s e c . ( t o t a l 4 0 cc ) w i t h a 1 2 - 1 6 sec. d e l a y . I m a g e s w e r e a c q u i r e d u s i n g 3 m m c o l l i m a t i o n a n d 3 m m . / s e c , t a b l e t r a v e l . HCTA i m a g e s w e r e i n t e r p r e t e d i n consensus by 2 blinded interpreters and aided by cine review and multiplanar r e c o n s t r u c t i o n s [MPR] a n d i n f r a p o p l i t e a l a r t e r i a l d i s e a s e w a s g r a d e d b a s e d o n s e v e r i t y . C o m p a r i s o n was m a d e to f i n d i n g s o n c o n v e n t i o n a l a r t e r i o g r a p h y . Results: HCTA a c c u r a t e l y i d e n t i f i e d a l l i n f r a p o p l i t e a l a r t e r i e s s e e n o n arteriography and predicted the same grade of disease in 10 patients. A higher g r a d e o f d i s e a s e i n 3 a n d a l o w e r g r a d e in 1 p a t i e n t w a s p r e d i c t e d b y HCTA w h e n c o m p a r e d to a r t e r i o g r a p h y . C o n c l u s i o n : HCTA is a u s e f u l a n c i l l a r y m e t h o d f o r e v a l u a t i o n o f i n f r a p o p l i t e a l disease, and may provide additional information, particularly with severe d i s e a s e . A l a r g e r s e r i e s w i t h c o r r e l a t i o n to MR a n g i o g r a p h y a n d s u r g e r y w i l l h e l p d e f i n e its r o l e in t h e p r e o p e r a t i v e e v a l u a t i o n o f p a t i e n t s w i t h l o w e r extremity ischemia.
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Assessment of Reperfused Myocardial Infarction Using Contrast Enhanced Spin Echo and Gradient Recalled Echo MR Imaging J.F. Geschwind, M.D., M.Saeed, Ph.D., M. Wendland, Ph.D., D. Szolar, M.D., C.B. Higgins, M.D. University of California at San Francisco.
PURPOSE: The purpose of this study was to demonstrate the effects of various doses of gadodiamide injection on myocardial contrast and relaxation times (T2 and T2*) in a rat model of iscbemia/repeffusion. METHODS: Rats (n=28) were subjected to 1 hour coronary artery occlusion followed by 1 hour roporfusion. Animal . . . . . divided into 4 groups (n=7 per group): group I r~eive~_nocontrastmedinm whereas groups 2-4 received 0.2, 0.5, 1.0 mmol/kg gadodiamide, respectiiveh p y, ati 45minutes e reperfusion. Hearts were then excised and imaged (2T imager) using spin-echo TI- (TR/TE-300/20) an~ T2-weighted (TR/TE=4000/80), 4 echo T2-wetghted (TR=4000/TE=20,40,60,80),and gradient recalled echo (T2*) imaging sequences. At the conclusion of MRI, hearts were stained with histochemieal staining to verify the presence of injury. RESULTS: MR images acquired prior to the administration of the contrast medium showed no evidence of myocardial injury. Reperfused ischemically injured rayocardium could be depleted as a .high-mtensay region or 'hot spot' on gadediamide-enhanced Tl-weighted images and as a low-signal regron or 'cold spot' on gadodiamide-enhanced T2-walghted images. Relative T2-weighted enhancement (contrast) and change in T2 relaxation time were dose dependent e.g. 0.81+0.1 and 0.90,2-0.04 msee, respectively, at a dose of 0.2 mmol/kg and 0.48-+0.08 and 0.71i~0.03 msec following 1.0 remol/kg. Gadodiamideinduced T2* shortening was greater in reperfiased ischemieally injured myoeardiurn (70-80 % of gadediamide-enhanced normal myocardium). Detection of injured myocardium as a cold spot was also accomplished in the heart by using gradient recalled echo images. CONCLUSION: l) The net T1 and T2 effects induced by gadediamide depend on dose, volume of distribution, and MR imaging parameters. 2) Changes in T2 relaxation time correlated well with that of signal intensity. 3) Gadodiamide delineated reperfused ischemically injured myecardium using T1, T2, and T2* sensitive images.
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