Magnetic resonance imaging study of perianal abscess / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To investigate magnetic resonance imaging(MRI) manifestations of perianal abscess and to evaluate MRI diagnosis for perianal abscess.</p><p><b>METHODS</b>Fifty cases of perianal abscess between July 2007 and March 2009 were included in this study. MRI was performed using T1 weighted sequence in axial plane, T2 weighted sequence with fat saturation in axial, coronal and/or sagittal plane, and T1 weighted enhanced sequence with fat saturation in axial, coronal and/or sagittal plane. The location, size, shape, signal characteristics, and enhancement patterns of perianal abscess were analyzed.</p><p><b>RESULTS</b>Fifty cases with 51 perianal abscesses were identified. The abscess appeared slight hypo- or isointense signal on T1 weighted imaging, obviously hyperintense signal at cavity and isointense signal at wall on T2 weighted with fat saturation imaging, and marked enhancement at wall. The largest diameters ranged between 0.5 cm and 9.0 cm (mean 3.4±1.7 cm ) in abscess, between 0.2 cm and 8.0 cm(mean 2.7±1.7 cm) in cavity. The abscess was round, oblong and crescent in 23, 18 and 7 cases respectively, and was unilocular in 41 cases and multilocular in 10 cases. The abscess located between levator ani and intersphincteric groove in 23 cases, under intersphincteric groove in 3 cases, across levator ani and intersphincteric groove in one case, on levator ani in 7 cases, on intersphincteric groove in 16 cases and above levator ani in one case.</p><p><b>CONCLUSION</b>MRI is a noninvasive, convenient and highly accurate procedure for diagnosing perianal abscess, which can demonstrate the anatomical relationship between abscess and anal canal.</p>

Multidetector-row CT evaluation of acute bowel ischemia induced by embolization of superior mesenteric artery in experimental porcine models / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To evaluate the application of multi-detector row CT (MDCT) and CT angiography (CTA) for detecting early signs of acute bowel ischemia (ABI) in experimental porcine models.</p><p><b>METHODS</b>Twelve pigs were assigned to four groups with 3 in each group. The digital subtraction angiography of superior mesenteric artery (SMA) and the embolization of branches of SMA with gelatin sponge and blood clot were performed by percutaneous transfemoral artery puncture and catheterization. MDCT pre- and post-contrast scanning in the arterial, venous and delay phase and CTA with three-dimensional reconstruction were carried out at pre-operation, 3 h, 6 h, 9 h, and 12 h after occlusion. The normal mesenteric vascular anatomy, arterial occlusion, mesentery and bowel changes, and dynamic change were evaluated.</p><p><b>RESULTS</b>ABI changes were identified pathologically in all the 12 experimental pigs, and the severity of ischemia increased over time after embolization. CTA showed all 57 embolized branches of SMA and 29 of 34 unoccluded arterial branches with 5 false-positive vessel occlusions. The sensitivity and specificity of CTA were 100% and 85.3%, respectively. Thin-slab maximum intensity projection (TSMIP) revealed the disappearance of distal comb-like vessel branches and brush-like vasa recta, which were clearly delineated in the normal bowel segments. Using this criterion, TSMIP correctly defined 23 of 24 ischemic bowel segments and all the 12 normal bowel segments with a sensitivity of 95.8% and a specificity of 100%.</p><p><b>CONCLUSIONS</b>MDCT and CTA reliably define normal and occluded mesenteric vessels in the pig. It can easily detect ischemic bowel segment by identified early changes of ischemia. The early direct ischemic signs are occluded vessels, the disappearance of distal comb-like branches or brush-like vasa recta, and poor bowel enhancement. The early indirect sign is bowel dilatation with fluid collection.</p>

The value of multislice spiral computed tomography in demonstrating the relationship between bronchus and peripheral lung cancer / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the value of multislice spiral computed tomography (MSCT) in demonstrating the relationship between bronchus and peripheral lung cancer.</p><p><b>METHODS</b>We prospectively performed volumetric targeted scans of 0.5 mm collimation with MSCT and reconstructed images of multiplanar reconstruction (MPR), curved multiplanar reformations (CMPR) and surface shaded display (SSD) in 53 peripheral lung cancers. The results were compared with macroscopic and microscopic specimens.</p><p><b>RESULTS</b>(1) The third- to seventh-order branches of the bronchi were clearly shown in all patients by the designed protocol. CT demonstrated the tumor-bronchus relationship in 29 (96.7%) adenocarcinomas and 13 (76.5%) squamous-cell carcinomas. Statistic analysis showed that there was no significant difference between the two groups (chi(2) = 2.8, P > 0.05). (2) The tumor-bronchus relationship was identified as four types with MSCT. Type I: bronchus was obstructed abruptly by the tumor, type II: bronchus penetrated into the tumor with tapered narrowing and interruption, type III: bronchus lumen shown within tumor was patent and intact, type IV: bronchus ran at the periphery of the tumor with intact or narrowed lumen. (3) Type I was shown in 31 of 53 (58.5%) tumors with squamous-cell carcinoma slightly more common than adenocarcinoma. Type II and type III were seen equally in 8 of 53 (15.1%) tumors which occurred only in adenocarcinomas. Type IV was seen in 15 of 53 (28.3%) tumors with adenocarcinoma being slightly more frequent than squamous cell carcinoma. (4) The tumor at the fourth-order bronchus was more common in squamous cell carcinoma, whereas that at the fixth-order bronchus was more likely in adenocarcinoma.</p><p><b>CONCLUSION</b>Volumetric targeted scan of ultra-thin section with MSCT and followed by MPR, CMPR and SSD reconstruction can greatly improve the manifestation of the bronchioles and accurately demonstrate the patterns of tumor-bronchus relationship, thereby reflecting pathologic changes to some extent.</p>