Efficiency of MR imaging to orientate surgical treatment of posterior deep pelvic endometriosis.

OBJECTIVE: The purpose of this retrospective study was to evaluate the accuracy of MRI using pelvic-phased-array and endocavitary coils in detecting intestinal wall invasion by an endometriotic nodule. MATERIALS AND METHODS: Forty-seven patients (32.1 +/- 4.2 years) who were planned for a surgical cure of deep endometriosis underwent MRI with conventional sequences using both coils. A thin bright layer on T(2)-w with enhancement on post-Gd T(1)-w defined our MR pattern for muscular layer involvement. MR results were correlated with surgical and pathological findings of the removed nodule. RESULTS: MR results for Group 1 (both coils) achieved a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 100-63%, 96-92%, 90-70%, 100-85%, and 97-83% for endovaginal coil and phased-array coil, respectively. Group 2 (phased-array coil) had a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 73%, 93%, 84%, 88%, and 87% for this coil, respectively. CONCLUSION: Combined pelvic-phased-array and endovaginal coils are better than phased array alone in the detection of intestinal wall invasion. Easy to perform, it has to be considered as a preoperative staging for deep posterior endometriosis to orientate the surgical management.

Vascular renal anatomy and the ureteropelvic junction: preoperative multidetector CT scanning with split-bolus injection as a predictor of laparoscopic findings.

PURPOSE: To compare multidetector CT scan (MDCT) results with intraoperative findings in the detection of an inferior-pole pedicle crossing the ureteropelvic junction. PATIENTS AND METHODS: Over the 2-year study period, 35 patients receiving laparoscopic pyeloplasty underwent preoperative investigation with a novel MDCT protocol in order to detect crossing vessels. Postprocessing, including maximum intensity projection, volume-rendering technique, and multiplanar reconstruction, was used in addition to standard axial views. RESULTS: All the arteries found during laparoscopic surgery were detected by MDCT, but one radiologic false-positive was noted at the beginning of the series. Seven veins were not detected with MDCT. In the only case featuring an isolated inferior-pole vein, the aberrant vessel was identified by MDCT. CONCLUSION: Multidetector CT scanning is a highly accurate way of providing all the information necessary preoperatively concerning renal parenchymal anomalies, urinary stones, and collecting system and vessel anatomy. It helps physicians make appropriate therapeutic decisions and gives surgeons information about what they can expect during laparoscopic procedures.

Characterization of human renal stones with MDCT: advantage of dual energy and limitations due to respiratory motion.

OBJECTIVE: Our aim was to determine, using CT attenuation values, the chemical composition of 241 human renal stones placed in a jelly phantom and to analyze the influence of respiratory motion on the classification. MATERIALS AND METHODS: The stones were placed in a jelly simulating the X-ray attenuation of the kidneys. A dynamic platform was used to apply to the phantom free-breathing motion (sinusoidal motion in z-axis) and motion due to lack of maintenance of a breath-hold (5 mm x s(-1) in z-axis). Determination of the chemical composition was performed with mean CT attenuation values obtained at 80 and 120 kV and with dual-energy CT attenuation values. RESULTS: Two hundred forty-one human urinary stones were classified into six groups: uric acid, cystine, struvite, weddellite (calcium oxalate dihydrate), whewellite (calcium oxalate monohydrate), and brushite. With no motion, the use of dual energy enabled differentiation of all of the types of stones with statistically significant differences. Uric acid (-20 +/- 22 H), cystine (106 +/- 19 H), struvite (271 +/- 16 H), weddellite (323 +/- 5 H), brushite (415 +/- 30 H), and whewellite (510 +/- 17 H) were identified as distinct groups. Motion-induced mean CT attenuation values were significantly different from those obtained with no motion. With motion, dual-energy CT attenuation values did not allow differentiation of all stone types. CONCLUSION: Dual-energy CT attenuation values can be used to predict the chemical composition of stones in vitro. However, when slight motion is applied to renal stones during image acquisition, the values become significantly different from those obtained with no motion. Consequently, confusion arises in differentiating stone types. A perfect breath-hold has to be performed for in vivo use of attenuation value to discern stone type.

Accuracy of intermediate dose of furosemide injection to improve multidetector row CT urography.

OBJECTIVE: Evaluate the usefulness of intermediate dose furosemide to improve visualization of the intrarenal collecting system and ureter using MDCTU. MATERIALS AND METHODS: Two groups of 100 patients without urinary tract disease or major abdominal pathology underwent MDCTU. Group I (various abdominal indications) was performed without any additional preparation and Group II (suspicion of urinary tract disease) 10 min after injection of furosemide (20mg). MIP images of the excretory phase were post-processed. Maximal short-axis diameter of the pelvis and ureter were measured on axial images for all phases. Visualization of the collecting system wall and the identification of the whole ureter were assessed. RESULTS: Mean pelvic diameter before contrast was (7.4mm, S.D.+/-2.7; 13.4mm, S.D.+/-4.1), on cortico-medullary phase (8.4mm, S.D.+/-4.2; 14.3mm, S.D.+/-4), on nephrographic phase (8.1mm, S.D.+/-2.5; 14.8mm, S.D.+/-4) and on excretory phase (9.7 mm, S.D.+/-3.4; 14.9 mm, S.D.+/-4.5), respectively, for Groups I and II. Intrarenal collecting system wall was clearly identified on both corticomedullary and nephrographic phases in 91% of Group II against 20% of Group I. Opacification of the entire ureter was excellent on excretory phase in 96% of Group II against 13% of Group I. The difference between the mean values for the two groups was statistically significant for all phases (p<10(-9)). CONCLUSION: Intermediate-dose furosemide (20mg) before MDCTU is a very simple add-on for accurate depiction of pelvicalyceal details and collecting system wall without artefacts. The procedure is associated with a constant and complete visualisation of the entire urete.

Degradation of the z- resolution due to a longitudinal motion with a 64-channel CT scanner.

Isotropic acquisitions are routinely achievable with 64- channel CT scanners,. As it predecessors, it includes MultiPlanar Reformation (MPR) projection for the reconstruction of two-dimensional images and volume rendering for the creation of three dimensional images. The accuracy of images obtained with these postprocessing methods depends on the spatial resolution of image data acquired along the long axis of the patient (ie longitudinal, or z-inis spatial resolution). But physiologic motions can appear during a Computed Tomography (CT) exam and can leacd to a degradation of this spatial resolution. By using two different phantoms and a dynamic platform, we have studied the influence of a z-axis linear motion on the MPR images quality. Our results show that the corruption of the data results in the loss of information about the form, the contrast and/or the size of the scanned object. This corruption of data can lead to diagnostic errors by mimicking diseases or by masking physiologic details.

Influence of a longitudinal motion on image quality with a 64-channel CT scanner.

Physiologic motions can appear during a Computed Tomography (CT) exam. Even if some motions can be prevented, others are unavoidable. To tempt to correct the resulting artifacts, it is necessary to understand their apparition and their influence on the image quality. By using an anthropomorphic phantom and a dynamic platform, we have studied the influence of three different linear speeds on the quality of CT axial images. The results proved that the deformation, the detectability and the contrast of calcifications are of course dependent on the size and on the density of the calcification but also on the movement applied to them. The influence of the motion on the image quality depends on the studied object and cannot be predicted.

MR Imaging of papillary renal neoplasms: potential application for characterization of small renal masses.

The purpose of our study was to evaluate the role of MRI in demonstrating the precise nature of papillary renal tumors (P RCC) and its potential application to select patients for partial surgery. Ninety-seven tumors less than or equal to 3 cm in size [55 papillary renal cell carcinoma - 42 clear cell renal carcinoma (CC RCC)] were preoperatively evaluated by MRI. Imaging findings were assessed with a special focus on the aspect of the tumoral process. Correlations were performed with pathologic staging after surgery. At pathology, 92 tumors were established to be staged p T1 and 5 were p T3 ( 3 cases of CC RCC and 2 cases of P RCC). Ninety-four percent of papillary tumors exhibited low signal intensity with homogeneous pattern on T2-weighted images. All clear cell carcinoma were hyperintense and heterogeneous on T2-weighted sequence. Enhancement was lower and delayed in the papillary type in comparison with the clear cell type. MRI is accurate enough to predict the 'histologic' nature of papillary renal carcinoma. It is an additional argument to propose that the tumor can be removed by partial surgery.