Anatomical variations of the coeliac trunk and the mesenteric arteries evaluated with 64-row CT angiography.

PURPOSE: This study was undertaken to evaluate the accuracy of 64-row computed tomography angiography (CTA) in the study of vascular anatomy by assessing the incidence of anatomical variations of the origin of the coeliac trunk, mesenteric arteries and collateral branches. MATERIALS AND METHODS: Sixty patients were evaluated with 64-row CTA (VCT, General Electric Healthcare, Milwaukee, WI, USA) with a collimation of 0.625 mm after the injection of iodinated nonionic contrast material (4 ml/s). Exclusion criteria were the presence of any pathological condition likely to affect normal vascular anatomy. RESULTS: The coeliac trunk had a normal trifurcation in 56.7% of cases. The common hepatic artery was normal in 60% of patients. The inferior pancreaticoduodenal arteries were either absent or not assessable in 8.3% of cases and there was a double trunk in 5%, a common trunk in 83.3% and a single vessel in 3.3%. The number of jejunal and ileal arteries ranged from a minimum of six to a maximum of 13 (mean value 8.7+/-1.34). The Riolan arcade was assessable in 31.7% and developed in 68.4% of these. CONCLUSIONS: The 64-row CTA enables visualisation of small vessels and accessory arteries that are difficult to identify with other techniques. The technique's high sensitivity allowed us to observe that the prevalence of vascular abnormalities is higher than that reported in the literature.

Contrast enhanced magnetic resonance imaging of the terminal ileum in children with Crohn's disease.

BACKGROUND AND AIMS: Recently, magnetic resonance imaging (MRI) has been introduced in the diagnosis of patients with inflammatory bowel disease (IBD). However, it is still rarely reported in paediatric IBD. We studied the diagnostic value of gadolinium enhanced MRI in revealing inflammation of the distal ileum in children with Crohn's disease (CD) and in differentiating them from patients with other inflammatory diseases of the gut. MRI was performed using a polyethylene glycol (PEG) solution as oral contrast agent to distend the small bowel (CE-PEG-MRI). SUBJECTS AND METHODS: Seventy five consecutive patients (median age 13.6 years, range 8-17) with suspected CD underwent ileocolonoscopy with biopsy and CE-PEG-MRI. CD activity was measured by the paediatric Crohn's disease activity index (PCDAI). CE-PEG-MRI was evaluated with an overall score calculated, taking into account both wall thickness and contrast enhancement. RESULTS: Active CD with distal ileitis was diagnosed in 26 cases, active ulcerative colitis (UC) in 18, and spondyloarthropathy and indeterminate ileocolitis in 11; 20 children served as controls. In all CD patients, CE-PEG-MRI revealed a marked ileal involvement with increased wall thickness and parietal contrast enhancement and showed a high concordance with endoscopy and histology, whereas the test was negative in all controls. Of the 18 UC patients, CE-PEG-MRI was negative in 15 and showed a mild parietal contrast enhancement of the terminal ileum in only three of seven patients with backwash ileitis. Among the group of spondyloarthropathy patients, six had mucosal erosions and five mild superficial ileitis: CE-PEG-MRI was negative in four and revealed only mild parietal contrast enhancement of the ileal wall in seven. CE-PEG-MRI did not show an increase in wall thickness of the distal ileum in any of the UC or spondyloarthropathy patients. The sensitivity and specificity of CE-PEG-MRI related to the presence of erosive ileitis, as documented by endoscopy, were 84% and 100%, respectively. In addition, the test correlated markedly with endoscopy and histology in the entire population (r=0.94; r=0.95, respectively) as well as with the PCDAI in CD patients (r=0.91). CONCLUSIONS: In children with active CD, CE-PEG-MRI is a very sensitive and specific test for the detection of distal ileitis and for differentiation from other inflammatory diseases of the gut. The test could also be useful for the firstline diagnostic approach in children with suspected CD. The high correlation of CE-PEG-MRI with ileal endoscopy and histology as well as with PCDAI makes this test of great interest for future studies as a tool for monitoring the clinical course and the effect of therapy in CD patients.

Magnetic Resonance Imaging of the anal canal using high resolution sequences and phased array coil: visualization of anal sphincter complex.

PURPOSE: To assess the normal anatomy of the anal sphincter complex using high-resolution MR imaging with phased -array coil. MATERIAL AND METHODS: Twenty patients, 13 males and 7 females, ranging in age between 27 and 56 years underwent MRI evaluation of the pelvic region, using a superconductive 1.5 T magnet (maximum gradient strength, 25 mT/m; minimum rise time 600 microseconds, equipped with phased-array coil. High-resolution T2-weighted Turbo Spin Echo sequences (TR, 4055 ms; TE, 132 ms; matrix 390x512; in-plane resolution, 0.67x0.57 mm) were acquired on multiple axial, sagittal and coronal planes. Images were reviewed by two experienced gastrointestinal radiologists in order to evaluate the normal anal sphincter complex. RESULTS: Optimal image quality of the anal sphincter complex was obtained in all cases. Different muscular layers were observed between the upper and lower aspects of the anal canal. In the lower part of the anal canal, internal and external sphincter muscles could be observed; in the upper part, puborectal and internal sphincter muscles were depicted. Good visualization of intersphincteric space, levator ani muscle and ischioanal space was also obtained in all cases. CONCLUSIONS: High-resolution MR images with phased-array coil provide optimal depiction of the anal canal and the anal sphincter complex.

[Multislice spiral CT angiography in the evaluation of the anatomy of splanchnic vessels: preliminary experience]. / Valuzazione dell'anatomia dei asi splancnici con angio-TC spirale multistrato: esperienza clinica preliminare.

PURPOSE: The aim of this study was to optimize the protocol for multislice spiral CT angiography and to assess the ability of the technique to detect the anatomy of splanchnic vessels, using volume rendering as reconstruction algorithm. MATERIAL AND METHODS: The anatomy of splanchnic vessels was studied in 19 patients (11 men, 8 women, age range 38-83 years) undergoing CT of the abdomen and pelvis. All examinations were performed with a multislice spiral CT scanner (Somatom Plus 4 Volume Zoom; Siemens, Erlangen, Germany) using the following parameters: collimation, 1 mm; slice width, 1 mm; table feed, 8 mm/sec; reconstruction interval, 1 mm; mAs, 120; kVp, 120. Before the study, the patients received 800 ml of water as oral contrast agent to opacify the stomach and small bowel. A nonionic contrast medium (130-140 ml; Xenetix 350, Guerbet, Aulnay-Sous-Bois, France) was infused intravenously at a rate of 3-5 ml/sec. Two scans of the abdomen and pelvis were obtained at 20-25 sec (arterial phase) and 60-65 sec (venous phase) after starting contrast medium injection. Image elaboration was performed using Vitrea 2.2 (Vital Images; Minneapolis, Minn., USA), a software with volume-rendering capabilities. RESULTS: All major arterial (celiac trunk, superior mesenteric artery, and inferior mesenteric artery) and venous (portal vein, superior mesenteric vein, inferior mesenteric vein, and splenic vein) vessels could be evaluated with excellent detail in all patients. Side branches, including small collaterals, could also be easily visualized. Volume rendered images always provided better understanding of the 3D anatomic relationships among splanchnic vessels and surrounding organs. DISCUSSION AND CONCLUSIONS: Multislice spiral CT angiography allows for optimal depiction of the anatomy of splanchnic vessels. It can be anticipated that the clinical applications of this imaging modality in the study of splanchnic vessels will be greatly expanded. However, further studies are necessary to rigorously compare the results of multislice spiral CT angiography with conventional angiography in terms of diagnostic accuracy.

[Diffusion-weighted echo-planar sequences for the evaluation of the upper abdomen: technique optimization]. / Utilizzazione delle sequenze echo-planari pesate in diffusione per lo studio dell'addome superiore. Ottimizzazione della tecnica.

PURPOSE: To optimize the technique for the evaluation of molecular diffusion in the abdomen. MATERIAL AND METHODS: Fifteen healthy volunteers, 6 males and 9 females, ranging in age between 24 and 31 years underwent an MRI evaluation of the upper abdomen, using a superconductive 1.5T magnet (maximum gradient strength, 25 mT/m; minimum rise time 600 ms), equipped with phased array abdominal multicoil. Diffusion study was performed with a single-shot Inversion Recovery Spin-Echo Echo-planar sequence (IR-SE-EPI) with the following parameters: TR = infinite; TE=101 ms; matrix 128 yen 128; receiver bandwidth 2080 Hz/pixel; slices: n.20; slice thickness: 8 mm; acquisition time: 5.41 s. For diffusion weighting the following b values were employed: b=30 mm/s2, b=300 mm/s2 e b=500 mm/s2. Both qualitative and quantitative (calculation of linear regression analysis and of apparent diffusion coefficient) image analysis was performed. RESULTS: Image quality was graded as diagnostic in all the cases. Image quality decreased with the increase of b values: at low b values, the anatomy of upper abdominal organs was easily recognized, whereas, at high b values, the same organs could not be adequately assessed unless the images were compared with those obtained with low b values. Magnetic susceptibility artifacts were observed in all the cases; no significant chemical-shift artifacts were observed as the fat saturation pre-pulse was employed. Quantitative analysis demonstrated an apparent diffusion coefficient of 1.58 s/mm2 for the liver, 1.61 s/mm2 for the spleen and 5,14 s/mm2 for the gallbladder. A statistically significant difference (p<0.001) was observed between parenchymatous organs (liver and spleen) and gallbladder, presenting as a stationary fluid. CONCLUSIONS: Diffusion-weighted MR sequences may be implemented for abdominal studies, but the optimization of same parameters is slightly different compared with neuroradiologic applications. The potential applications are interesting above all as regards the characterization of focal liver lesions. Further developments are awaited in both sequence optimization (greater stability and lower sensitivity to magnetic susceptibility artifacts) and data analysis, with more complex algorithms able to better quantify the real diffusion coefficient.