Gadobenate Dimeglumine-enhanced MR of VX2 Carcinoma in Rabbit Liver: Usefulness of the Delayed Phase Imaging and Optimal Pulse Sequence

PURPOSE: To assess the diagnostic value of delayed imaging using gadobenate dimeglumine(MultiHance) and to determine the optimal pulse sequence for the detection of VX2 carcinoma lesions in the rabbit. MATERIALS AND METHODS: Twelve VX2 carcinomas implanted in the livers of eleven New Zealand rabbits were studied. All patients underwent an MR protocol consisting of precontrast T2-and T1-weighted sequences, followed by repetition of the T1-weighted sequence at 0 to 30 (arterial phase), 31-60 (portal phase), and 40 minutes (delayed phase) after the intravenous administration of 0.1 mmol/kg of gadobenate dimeglumine. The signal-to-noise ratio (SNR) of the liver and VX2 tumor, and the lesion-to-liver contrast-to-noise ratio (CNR) of precontrast and postcontrast MR images were quantitativlely analyzed, and two experienced radiologists evaluated image quality in terms of lesion conspicuity, artifact, mass delineation, and vascular anatomy. RESULTS: Liver SNR was significantly higher at delayed imaging than at precontrast, arterial, and portal imaging (p<0.05), while lesion SNR was significantly higher at delayed imaging than at precontrast imaging (p<0.05). Lesion CNR was higher at delayed imaging than at precontrast and portal phase imaging (p<0.05), but there was no difference between arterial and delayed imaging. The latter provided better mass delineation than precontrast, arterial and portal phase imaging (p<0.05). While in terms of lesion conspicuity and vascular anatomy, the delayed phase was better than the arterial phase (p<0.05) but similar to the precontrast and portal phase. During the delayed phase, the gradient-echo sequence showed better results than the spin-echo in terms of liver SNR, and lesion SNR and CNR (p<0.05). CONCLUSION: Because it provides better lesion conspicuity and mass delineation by improving liver SNR and lesion-to-liver CNR, the addition of the delayed phase to a dynamic MRI sequence after gadobenate dimeglumine administration facilitates lesion detection. For delayed-phase imaging, the gradient-echo sequence is superior to the spin-echo sequence.

The Usefulness of T2-weighted MR Urography and Contrast Enhanced MR Urography in the Evaluation of Obstructive Uropathy: Comparisonal Study with Antegrade Pyelography1

PURPOSE: To compare the efficacy of contrast-enhanced and T2-weighted magnetic resonance urography (MRU) for the depiction of obstruction and evaluation of the causes of obstructive uropathy with that of antegrade pyelography. MATERIALS AND METHODS: Twenty-five patients with obstructive uropathy who underwent percutaneous nephrostomy (PCN) and antegrade pyelography (AGP) were included in the study. We performed MR urography, comprising half-Fourier acquisition single-shot turbo spin-echo (HASTE) T2-weighted imaging and 3-D fast imaging with steady state precession (3-D FISP) T1-weighted imaging after gadolinium enhancement and compared the quality of the images of both the HASTE and 3-D FISP MRU techniques in terms of their depiction of the dilated pelvocalyceal system, and the level, type, and causes of obstruction. RESULTS: In terms of anatomical depiction of the pelvocalyceal system (p=0.002) and the causes of obstruction (p=0.003), T1-weighted MRU using 3D-FISP was significantly better than T2-weighted MRU using the HASTE sequence. Regarding level of obstruction, T2-weighted MRU using the HASTE sequence and contrastenhanced T1-weighted MRU using 3D-FISP showed an accuracy of 76% (19/25) and 84% (21/25), respectively. In terms of type of obstruction, the accuracy of T2-weighted MRU and T1-weighted CEMRU was 72%(18/25) and 88% (22/25), respectively. CONCLUSION: T2-weighted MRU and T1-weighted CEMRU provided both anatomical information and that relating to impaired renal function. The two modelities played a complementary role and their use could decrease the unnecessary use of invasive diagnostic examination for the evaluation of obstructive uropathy.

Enhanced CT in the Patients with Pleural Effusion: Differential Findings between Exudates and Transudates

PURPOSE: To evaluate the differential findings of CT in the differention of pleural exudates and transudates. MATERIALS AND METHODS: One hundred and thirteen consecutive patients (113 effusions) underwent enhanced thoracic CT ; the scans were evaluated for the presence or absence and appearance of enhancing parietal pleural thickening and extrapleural fat thickening. Thoracentesis was performed to measure pleural and serum total protein andlactate dehydrogenase(LDH) values. Effusions were classified as exudates by using Light's criteria. RESULTS: Eighty-eight effusions were exudates and 25 were transudates. Eighty-three of the 88 exudates (93%) were associated with enhanced parietal pleural thickening ; seventy of the 88 (80%) were associated with extrapleural fat thickening. Four of the 25 transudates were associated with parietal pleural thickening and extrapleural fat thickening, both of which were the most important factors in differentiating beteen pleural exudates and transudates(p<0.05). CONCLUSION: Parietal pleural thickening and extrapleural fat thickening on contrast-enhanced CT almost always in dicate the presence of pleural exudates.

Treatment of Esophagorespiratory Fistulas Associated with Esophageal Carcinoma: Effectiveness and Problems of a Modified Gianturco Stent

PURPOSE: To evaluate the effectiveness and problems of Gianturco stent for treatment of esophagorespiratory fistulas caused by esophageal carcinoma. MATERIALS AND METHODS: In a 6~year period, we have treated 95 patients of esophageal carcinomas with silicone-covered modified Gianturco stent. Among those patients, ten had an esophagorespiratory fistula. We retrospectively analyzed the effect of stent for the occlusion of esophagorespiratory fistula, food intake capacity of patients, clinical and procedural problems of the stent. RESULT: After procedure, all fistulas were occluded successfully. Of the 10 patients, two could swallow all kinds of food, four most of foods, three soft foods, and one only liquid foods. In one patient, the fistula was reopened probably resulting from the reflux due to the presence of another lesion in the distal esophagus at 1 week after procedure. Two patients complained of dyspnea due to tracheal compression by the proximal tip of the stent and tracheal invasion of tumor after 4 and 11 weeks. In one patient, fistula was recurred due to tumor overgrowth on proximal and distal portion after 24 weeks. The fistulas recurred from the tumor overgrowth or reflux were sucessfully treated with another esophageal stent. The tracheal compression by the proximal tip of the stent and invasion by esophageal cancer was treated with tracheal stent and radiation therapy. CONCLUSION: Insertion of silicone-covered modified Gianturco stent was an effective method for the palliative treatment of esophagorespiratory fistula caused by esophageal cancer. Simultaneous use of tracheal stent is also recommended in patients with tracheal compression by the proximal tip of the stent and invasion by esophageal cancer.