MR Evaluation of Rectal Carcinoma: Pelvic Phased-Array Coil versus Endorectal-Pelvic Phased-Array Coil

PURPOSE: To compare the accuracy of MR imaging using an endorectal-pelvic and a pelvic phased-array coil forpreoperative local staging of rectal carcinoma. MATERIALS AND METHODS: To determine preoperative staging, 38patients with rectal carcinoma underwent MR imaging. All patients were examined with both an endorectal-pelvic anda pelvic phased-array coil. All underwent surgery and staging was pathologically confirmed. Two radiologistsblinded to pathologic stage analyzed perirectal invasion and perirectal node metastasis, and scored according to afour-point scale. Radiologic and pathologic findings were correlated. Receiver operating characteristic (ROC)analysis of Wilcoxon statistic (W values) was used to compare diagnostic accuracy between the two different MRmethods. Interobserver variation was measured using kappa statistics. RESULTS: For perirectal invasion, T1WIendorectal-pelvic phased-array coil images (reader 1: 0.854, reader 2: 0.818) showed higher W values than pelvicphased-array coil images (reader 1: 0.755, reader 2: 0.811). On T2WI, W values were higher according to pelvicphased-array coil images (reader 1: 0.828, reader 2: 0.861) than according to endorectal-pelvic phased-array coilimages (reader 1: 0.813, reader 2: 0.786). For perirectal node metastasis, pelvic phased-array coil images (reader1: 0.745, reader 2: 0.792) showed higher W values than endorectal-pelvic phased-array coil images (reader 1:0.722, reader 2: 0.775), according to both reader 1 and 2. The defference kappa values between the two readers wasless than 0.4 ; agreement between them was poor. CONCLUSION: The use of an endorectal-pelvic phased-array coildid not significantly improve the accuracy of assessment of perirectal invasion and perirectal node metastasis,and in MR imaging of rectal corcinoma, the routine use of an endorectal coil is not advocated.

Focal Hepatic Lesions: Dynamic Multi-slice MR Imaging

PURPOSE: To evaluate the dynamic enhancement patterns of focal hepatic lesions using breath-hold dynamic MR imaging for differential diagnosis. MATERIALS AND METHOD: Thirty three patients (24 men and 12 women, mean age of 55 years) with 56 known liver masses on CT scan and US underwent MR imaging with 1.5T. After Tl-weighted fast multiplanar spoiled gradient recalled (FMPSPGR) imaging, breath-hold FMPSPGR images were obtained at 0, 1, 3, 5, and 10 minutes after bolus injection of Gd-DTPA. The cases consisted of 16 hepatocellular carcinomas, 24 hemangiomas, 6 metastases, 3 cholangiocellular carcinomas, and 7 hepatic cysts. The dynamic enhancement patterns were evaluated on the basis of initial enhancement study and, the degree of enhancement was also levaluaied. RESULTS: Of 24 hemangiomas, most cases showed centripetal filling-in pattern of enhancement except 3 cases which showed homogeneous enhancement pattern on the early dynamic phase. All hemangiomas showed very high signal intensity which persisted to the delayed phase. The eccentric enhancement pattern was the most common type in hemangiomas (63%). Hepatocellular carcinomas had heterogeneous enhancement pattern on early and delayed phase (81, 88%) and showed diminished signal intensity on the delayed images. 14 of 16 hepatocellular carcinomas (88%) had peritumoral halo. Variable enhancement pattern was observed in metastases including progressive centripetal filling-in pattern (67%). All metastases showed prominent peritumoral halos and low signal intensity. Cholangiocellular carcinomas showed early centripetal filling-in and heterogeneous enhancement pattern on delayed phase. None of hepatic cysts showed enhancement. CONCLUSIONS: Dynamic breath-hold MR imaging with Gd enhancement allows accurate assessment of hemodynamic status of hepatic lesions and is useful in differential diagnosis of focal hepatic lerions.

Focal Hepatic Lesions: Dynamic Multi-slice MR Imaging

PURPOSE: To evaluate the dynamic enhancement patterns of focal hepatic lesions using breath-hold dynamic MR imaging for differential diagnosis. MATERIALS AND METHOD: Thirty three patients (24 men and 12 women, mean age of 55 years) with 56 known liver masses on CT scan and US underwent MR imaging with 1.5T. After Tl-weighted fast multiplanar spoiled gradient recalled (FMPSPGR) imaging, breath-hold FMPSPGR images were obtained at 0, 1, 3, 5, and 10 minutes after bolus injection of Gd-DTPA. The cases consisted of 16 hepatocellular carcinomas, 24 hemangiomas, 6 metastases, 3 cholangiocellular carcinomas, and 7 hepatic cysts. The dynamic enhancement patterns were evaluated on the basis of initial enhancement study and, the degree of enhancement was also levaluaied. RESULTS: Of 24 hemangiomas, most cases showed centripetal filling-in pattern of enhancement except 3 cases which showed homogeneous enhancement pattern on the early dynamic phase. All hemangiomas showed very high signal intensity which persisted to the delayed phase. The eccentric enhancement pattern was the most common type in hemangiomas (63%). Hepatocellular carcinomas had heterogeneous enhancement pattern on early and delayed phase (81, 88%) and showed diminished signal intensity on the delayed images. 14 of 16 hepatocellular carcinomas (88%) had peritumoral halo. Variable enhancement pattern was observed in metastases including progressive centripetal filling-in pattern (67%). All metastases showed prominent peritumoral halos and low signal intensity. Cholangiocellular carcinomas showed early centripetal filling-in and heterogeneous enhancement pattern on delayed phase. None of hepatic cysts showed enhancement. CONCLUSIONS: Dynamic breath-hold MR imaging with Gd enhancement allows accurate assessment of hemodynamic status of hepatic lesions and is useful in differential diagnosis of focal hepatic lerions.

Comparison of Conventional Spin Echo, Fast Spin Echo and Fast Multiplanar Spoiled Gradient Recalled Imaging for Evaluation of Focal Hepatic Lesions

PURPOSE: To compare the detectability and conspicuity of focal hepatic lesions among conventional spin echo techniqueniques and fast scanning techniqueniques in MR imaging. MATERIALS AND METHOD: 36 patients (24 men and 12 women, mean age of 54 years) with suspected liver mass on CT scan and US underwent MR imaging at 1.5 T system. Conventional spin echo T1, T2 weighted imaging, T2 weighted fast spin echo, T1 weighted fast multiplanar spoiled gradient recalled(FMPSPGR) imaging and Gd-enhanced FMPSPGR(Gd-FMPSPGR) were performed. 16 cases of hepatocellular carcinoma, 13 cases of hemangioma, 3 cases of metastasis, 3 cases of cholangiocarcinoma, and 1 case of lymphoma were included. Lesion conspicuity and number of detected hepatic masses were compared among the MR sequences. RESULTS: Overall 63 hepatic lesions were detected in 36 patients. Lesion detection' was 63(100%) with Gd-FMPSPGR, 62(98%) with non-enhanced FMPSPGR, 58(92%) with SE T2WI, 56(89%) with SE T1WI and 54 (86%)with FSE. For solid tumors, the contrast to noise ratio was greatest on Gd-FMPSPGR which was significantly higher than any other sequences. For hemangiomas it was greatest on SE T2WI and was significantly higher than SE T1WI. In the qualitative assessment, Gd-FMPSPGR was preferred for both solid mass lesion and hemangioma. FSE was inferior to SE T2WI for lesion detection and conspicuity without statistical significance. CONCLUSIONS: For the evaluation of focal hepatic lesions, breath-hold FMPSPGR with and without contrast enhancement may replace the conventional SE T1WI. Because FSE was inferior to SE T2WI when the later is used with respiratory compensation in some cases, it is difficult to replace the SE T2WI with FSE. But FSE, FMPSPGR and Gd-FMPSPGR images, when combined, may replace SE T1WI and SE T2WI.

Comparison of Fast Spin Echo, Fast Multiplanar Spoiled Gradient Recalled and Conventional T1 and T2 Weighted Imaging for Experimentally Induced Hepatic Tumors in Rats

PURPOSE: To compare the ability of tumor detection and the lesion conspicuity between T1- and T2-weighted fast scanning sequences and T1- and T2-weighted conventional spin echo techniques in MR imaging of hepatic tumors. MATERIALS AND METHOD: Hepatic tumors were induced on 13 male Sprague-Dawley rats by feeding 3'-methyl-dimethylethylaminoazobenzene mixed with Miller's III formula for 12 weeks. MR images were obtained with 1.5T magnet with dual TMJ coil(Signa, GE Medical Systems, Milwaukee, USA). Animals were anesthesized with 150mg/kg of ketamine hydrochloride. T2 weighted fast spin echo(FSE), conventional spin echo(CSE) T2- and T1WI, fast multiplanar spoiled gradient recalled(FMPSPGR) imaging were obtained. Number of detected, tumors and contrast-to-noise ratio of the tumors were compared for each sequence. RESULTS: Overall 110 tumors were developed. 75% of the tumors were detected on FSE, 65% on FMPSPGR, 41% on conventional T2WI, and 41% on T1WI images. For tumors more than 5mm in diameter, sensitivity was 88% on FMPSPGR, 65% on conventional T2WI, and 81% on TIWI images respectively. CNR of the tumor was 28.94 +/- 21.6 on FSE, 13.57 +/- 8.64 on FMPSPGR, 12.62 +/- 10.65 on CSE T2WI, and 9.47 +/- 8.05 on CSE TIWI images, which was significantly high on FSE (p<0.05). CONCLUSION: Fast spin echo T2 WI shows highest sensitivity and tumor-to-liver contrast. FMPSPGR imaging is also favorably comparable with conventional T1WI. Therfore, these two pulse sequences can be useful in clinical condition for hepatic MR imaging.

Normal Appearance of the Prostate and Seminal Tract: MR Imaging using an Endorectal Surface Coil

PURPOSE: To assess the ability of MR imaging with an endorectal surface coil for the depiction of noraml anatomical structure of prostate and its adjacent organs. MATERIALS AND METHOD: MR imaging using an endorectal surface coil was performed in 23 male patients (age;20-75) to evaluate various prostatic and vasovesicular disorders, i.e., 14 cases of ejaculatory problems, 3 cases of hypogonadism, and 4 cases of prostatic cancers and 2 cases of benign prostatic hyperplasia. MR images were obtained with axial, sagittal and coronal fast spin echo long TR/TE images and axial spin echo short TR/TE images. Field of views was 10--12 cm and scan thickness was3--5 mm. RESULTS: Depiction of normal anatomcial structures was excellent in all cases. On T2WI, zonal anatomy of the prostate and prostatic urethra, urethral crest, and ejaculatory duct were cleary visualized. On T1WI, periprostatic fat plane is more cleary visualized.