Increased fronto-striatal reward prediction errors moderate decision making in obsessive-compulsive disorder.

BACKGROUND: Obsessive-compulsive disorder (OCD) has been linked to functional abnormalities in fronto-striatal networks as well as impairments in decision making and learning. Little is known about the neurocognitive mechanisms causing these decision-making and learning deficits in OCD, and how they relate to dysfunction in fronto-striatal networks. METHOD: We investigated neural mechanisms of decision making in OCD patients, including early and late onset of disorder, in terms of reward prediction errors (RPEs) using functional magnetic resonance imaging. RPEs index a mismatch between expected and received outcomes, encoded by the dopaminergic system, and are known to drive learning and decision making in humans and animals. We used reinforcement learning models and RPE signals to infer the learning mechanisms and to compare behavioural parameters and neural RPE responses of the OCD patients with those of healthy matched controls. RESULTS: Patients with OCD showed significantly increased RPE responses in the anterior cingulate cortex (ACC) and the putamen compared with controls. OCD patients also had a significantly lower perseveration parameter than controls. CONCLUSIONS: Enhanced RPE signals in the ACC and putamen extend previous findings of fronto-striatal deficits in OCD. These abnormally strong RPEs suggest a hyper-responsive learning network in patients with OCD, which might explain their indecisiveness and intolerance of uncertainty.

Diagnostic accuracy of translucency rendering to differentiate polyps from pseudopolyps at 3D endoluminal CT colonography: a feasibility study.

PURPOSE: The aim of this study was to assess the accuracy of translucency rendering (TR) in computed tomographic (CT) colonography without cathartic preparation using primary 3D reading. MATERIALS AND METHODS: From 350 patients with 482 endoscopically verified polyps, 50 pathologically proven polyps and 50 pseudopolyps were retrospectively examined. For faecal tagging, all patients ingested 140 ml of orally administered iodinated contrast agent (diatrizoate meglumine and diatrizoate sodium) at meals 48 h prior to CT colonography examination and two h prior to scanning. CT colonography was performed using a 64-section CT scanner. Colonoscopy with segmental unblinding was performed within 2 weeks after CT. Three independent radiologists retrospectively evaluated TRCT clonographic images using a dedicated software package (V3D-Colon System). To enable size-dependent statistical analysis, lesions were stratified into the following size categories: small (< or =5 mm), intermediate (6-9 mm), and large (> or =10 mm). RESULTS: Overall average TR sensitivity for polyp characterisation was 96.6%, and overall average specificity for pseudopolyp characterisation was 91.3%. Overall average diagnostic accuracy (area under the curve) of TR for characterising colonic lesions was 0.97. CONCLUSIONS: TR is an accurate tool that facilitates interpretation of images obtained with a primary 3D analysis, thus enabling easy differentiation of polyps from pseudopolyps.

Semiparametric models and inference for biomedical time series with extra-variation.

Biomedical trials often give rise to data having the form of time series of a common process on separate individuals. One model which has been proposed to explain variations in such series across individuals is a random effects model based on sample periodograms. The use of spectral coefficients enables models for individual series to be constructed on the basis of standard asymptotic theory, whilst variations between individuals are handled by permitting a random effect perturbation of model coefficients. This paper extends such methodology in two ways: first, by enabling a nonparametric specification of underlying spectral behaviour; second, by addressing some of the tricky computational issues which are encountered when working with this class of random effect models. This leads to a model in which a population spectrum is specified nonparametrically through a dynamic system, and the processes measured on individuals within the population are assumed to have a spectrum which has a random effect perturbation from the population norm. Simulation studies show that standard MCMC algorithms give effective inferences for this model, and applications to biomedical data suggest that the model itself is capable of revealing scientifically important structure in temporal characteristics both within and between individual processes.

Multidisciplinary approach for the study of an Egyptian coffin (late 22nd/early 25th dynasty): combining imaging and spectroscopic techniques.

This paper demonstrates that an educated methodology based on both non-invasive and micro invasive techniques in a two-step approach is a powerful tool to characterize the materials and stratigraphies of an Egyptian coffin, which was restored several times. This coffin, belonging to a certain Mesiset, is now located at the Museo Civico Archeologico of Bologna (inventory number MCABo EG 1963). Scholars attributed it to the late 22nd/early 25th dynasty by stylistic comparison. The first step of the diagnostic approach applied imaging techniques on the whole surface in order to select measurements spots and to unveil both original and restored areas. Images and close microscopic examination of the polychrome surface allowed selecting representative areas to be investigated in situ by portable spectroscopic techniques: X-ray Fluorescence (XRF), Fiber Optic Reflectance Spectroscopy (FORS) and Fourier Transform Infrared spectroscopy (FTIR). After the analysis of the results coming from the first step, very few selected samples were taken to clarify the stratigraphy of the polychrome layers. The first step, based on the combination of imaging and spectroscopic techniques in a totally non-invasive modality, is quite unique in the literature on Egyptian coffins and enabled us to reveal many differences in the ground layer's composition and to identify a remarkable number of pigments in the original and restored areas. This work offered also a chance to check the limitations of the non-invasive approach applied on a complex case, namely the right localization of different materials in the stratigraphy and the identification of binding media. Indeed, to dissolve any remaining doubts on superimposed layers belonging to different interventions, it was necessary to sample few micro-fragments in some selected areas and analyze them prepared as cross-sections. The original ground layer is made of calcite, while the restored areas show the presence of either a mixture of calcite and silicates or a gypsum ground, overlapped by lead white. The original pigments were identified as orpiment, cinnabar and red clay, Egyptian blue and green copper based pigments. Some other pigments, such as white lead, Naples yellow, cerulean blue and azurite were only found in the restored areas.

Multislice spiral computed tomography in diagnosis and staging of pancreatic carcinoma: preliminary experience.

BACKGROUND: Computed tomography has become the modality of choice for preoperative evaluation of patients with suspected pancreatic carcinoma, although some limitations are well known. AIMS: To evaluate use of multislice spiral computed tomography in preoperative assessment of patients with suspected pancreatic carcinoma using volume-rendering as image reconstruction algorithm. PATIENTS: A total of 27 patients with suspected pancreatic carcinoma underwent multislice spiral computed tomography examination. METHODS: All studies were performed on a multislice computed tomography scanner with the following parameters: slice collimation, 1 mm; slice thickness, 1.25 mm; reconstruction interval, 1 mm; scan time, 22-25 sec; mAs, 165. Scans were acquired with a biphasic technique with a 30-sec (pancreatic phase) and a 70-sec (portal venous phase) delay time after start of contrast material injection. Diagnostic confirmation was obtained with surgical exploration, percutaneous biopsy, or with a combination of follow-up imaging studies. RESULTS: Multislice spiral computed tomography yielded correct diagnosis of pancreatic carcinoma in 20 cases (sensitivity, 95%; specificity, 100%). Positive predictive values for resectability and unresectability were 80% and 93.3%, respectively. Three-dimensional volume-rendered images improved diagnostic confidence in the depiction of major vascular structures. Two cases of anomalous origin of hepatic artery were also identified with volume-rendered images. CONCLUSIONS: Multislice technology improves accuracy of spiral computed tomography for diagnosis and staging of pancreatic carcinoma.

Abdominal tuberculosis with pancreatic involvement: a case report.

A case of abdominal tuberculosis with pancreatic involvement is described. A 27-year-old Italian male, with no known cause of immunodeficiency and with no evidence of pulmonary tuberculosis, was admitted to our division because of acute pancreatitis. Abdominal imaging revealed a large 'tumour-like' mass in the pancreas head compressing the distal choledochous, and multiple adenopathy. Histological examination of multiple specimens removed during explorative laparotomy revealed granulomas with giant cells, caseous necrosis, and positive Ziehl-Neelsen staining. Tissue culture was positive for Mycobacterium tuberculosis. Once specific medical treatment was started, the pancreatic damage completely resolved.

Combined therapy with GnRH analog plus growth hormone in central precocious puberty.

GnRH analogues (GnRHa) arrest pubertal development, and slow growth velocity (GV) and bone maturation, thus improving adult height in central precocious puberty (CPP). In some patients, however, GV decreases to such an extent that it compromises the improvement in predicted adult height (PAH) and therefore the addition of GH is suggested. Of 20 patients with idiopathic CPP (treated with GnRHa [depot-triptorelin] at a dose of 100 microg/kg every 21 days i.m. for at least 2-3 yr) whose GV fell below the 25th percentile for chronological age (CA), ten received, in addition to the GnRHa, GH at a dose of 0.3 mg/kg/wk, s.c. 6 days weekly, for 2-4 yr. Ten patients matched for BA, CA, and duration of GnRHa treatment who showed the same growth pattern but refused GH treatment, served to evaluate the efficacy of the addition of GH. No patient showed classical GH deficiency. Both groups discontinued treatment at a comparable BA (mean +/- SEM): 13.2 +/- 0.2 yr in GnRHa + GH vs 13.0 +/- 0.1 yr in the control group. At the conclusion of the study all the patients had achieved adult height. Adult height was considered to be attained when the growth during the preceding year was less than 1 cm, with a BA of over 15 yr. Patients of the group treated with GH + GnRHa showed an adult height significantly higher (p<0.001) than pretreatment PAH (160.6 +/- 1.3 vs 152.7 +/- 1.7 cm). Height SDS for BA significantly increased from -1.5 +/- 0.2 at start of GnRHa to -0.21 +/- 0.2 at adult height (p<0.001). Target height was significantly exceeded. The GnRH alone treated group reached an adult height not significantly higher than pretreatment PAH (157.1 +/- 2.5 vs 155.5 +/- 1.9 cm). Height SDS for BA did not change (from -1.0 +/- 0.3 at start of GnRHa to -0.7 +/- 0.4 at adult height). Target height was just reached but not significantly exceeded. The gain in centimeters obtained calculated between pretreatment PAH and final height was 7.9 +/- 1.1 cm in patients treated with GH combined with GnRH analogue while in patients treated with GnRH analogue alone the gain was just 1.6 cm +/- 1.2 (p=0.001). Furthermore, no side effects, bone age progression, or ovarian cysts, were observed in GnRHa + GH treated patients. In conclusion, a gain of 7.9 cm in adult height represents a significant improvement which justifies the addition of GH for 2-3 yr to conventional treatment with GnRH analogues in patients with central precocious puberty, and with a decrease in growth velocity so marked as to impair predicted adult height to below the third percentile.

[Complications of lung transplantation: clinical aspects and radiological findings]. / Complicanze del trapianto polmonare. Aspetti clinici e reperti radiologici.

In spite of improvements in the surgical technique of lung transplantation, early and late complications after surgery are not uncommon. The authors review the clinical aspects and radiological findings of these complications, including reperfusion edema, acute rejection, infections, airway complications, vascular complications, pleural complications, chronic rejection, omentopexy complications, transbronchial biopsy complications, post-transplantation lymphoproliferative disease and recurrence of the primitive disease. Early detection of these complications is important for early appropriate treatment, resulting in the decrease in morbidity and mortality of the transplanted patients.

[Hypochondroplasia: importance of radiological findings in the differential diagnosis of short statures of different origin]. / L'ipocondroplasia: importanza dei reperti radiologici nella diagnosi differenziale con basse stature di altra origine.

Hypochondroplasia is a genetic skeletal dysplasia characterized by disproportionate short stature, stocky appearance and several clinical and radiological features very similar, but much milder, than those of classical achondroplasia, including shortened and stubby long bones, decreased lumbo-sacral interpediculate distances, posterior scalloping of the lumbar vertebrae, metaphyseal flaring, and moderate macrocephaly. The condition may occasionally mimic short stature of familial, endocrine or metabolic origin. In the absence of clinical and laboratory diagnostic clues, radiological findings are of the utmost value in the diagnosis of this skeletal dysplasia and also in the differential diagnosis with other short-limbed dwarfisms. The genetic, clinical and radiological aspects of hypochondroplasia are briefly recalled, and the importance of some minor and frequently overlooked findings is stressed.

Multislice CT angiography of mesenteric vessels.

Due to several distinct advantages over conventional angiography (including minimal invasiveness, lower cost, and lower ionizing radiation exposure for patients and staff), computed tomography (CT) angiography has replaced diagnostic conventional angiography in several clinical situations. The recent introduction of multislice CT (MSCT) scanners has significantly improved CT angiographic applications, especially in the evaluation of the mesenteric vasculature. Thin-slice collimation protocols associated with powerful postprocessing procedures allow the display of mesenteric circulation with excellent detail. The purposes of this presentation are (a) to illustrate the imaging technique that can be used to obtain state-of-the-art MSCT angiographic images of the mesenteric vasculature, (b) to review the normal anatomy and anatomic variants of mesenteric vessels, and (c) to illustrate some of the potential clinical applications of MSCT angiography of the mesenteric vessels.

Multislice spiral computed tomography angiography of mesenteric arteries.

The introduction of multislice technology has improved and expanded the clinical applications of computed tomography angiography (CTA), and it is now possible to detect subtle vascular abnormalities. We optimised a high resolution CTA protocol to study the anatomy of mesenteric arteries with a multislice spiral CT scanner. We showed that multislice CTA produces images of high quality, with excellent anatomical visualisation of the main mesenteric trunks, and small collateral vessels. CTA may facilitate the diagnosis of vascular diseases, such as chronic mesenteric ischaemia, as well as acute disorders such as gastrointestinal bleeding.

[Optimization of the technique of virtual colonoscopy using a multislice spiral computerized tomography]. / Ottimizzazione della tecnica della colonscopia virtuale utilizzando un apparecchio di Tomografia Computerizzata spirale multistrato.

PURPOSE: To optimize scanning parameters for virtual colonoscopy utilizing a multislice Helical CT scanner in an in vitro study (using a homemade colonic phantom) and in a preliminary clinical study. MATERIAL AND METHODS: A colonic phantom was built using a plastic tube and 12 plastiline polyps were placed inside. The colonic phantom was studied with a multislice Helical CT scanner. Axial images were obtained with the phantom parallel to the long axis of the moving table (in order to simulate the evaluation of ascending and descending colon): oblique images were acquired with the phantom at 45 degrees relative to the long axis of the moving table (in order to simulate the evaluation of sigmoid colon and colonic flexures). Four different scanning protocols were tested: 1) slice collimation, 5 mm; slice width, 7 mm; table speed, 25 mm; reconstruction index, 5 mm; 2) slice collimation, 2.5 mm; slice width, 3 mm; table speed, 15 mm; reconstruction index, 3 mm; 3) slice collimation, 1 mm; slice width, 1.25 mm; table speed, 5 mm; reconstruction index, 1 mm; 4) slice collimation, 1 mm; slice width, 1.25 mm; table speed, 4 mm; reconstruction index, 1 mm. Quantitative analysis consisted in evaluation of the number of identified polyps and polyp size along the longitudinal axis. Qualitative analysis consisted in the evaluation of image artifacts and quality of 3D reconstructed images (step artifacts and polyp geometry distortion). This preliminary clinical study was performed in 12 patients (7 men and 5 women) who underwent multislice Helical CT colonography. We selected patients with clinical indications for conventional colonoscopy or after unsuccessful conventional colonoscopy. RESULTS: Multislice Helical CT colonography was 100% sensitive in the detection of all polyps and in all scanning protocols. With oblique scans, only a 3-mm polyp was missed during protocol 1 (sensitivity: 92%). Polyp geometry distortion was observed on longitudinal reconstructions, whereas no distortion was seen on axial images. Image quality was graded as optimal for protocols 2, 3, and 4; protocol 1 was graded as good on transverse scans and as poor on oblique scans. In our preliminary clinical study, two colonic carcinomas and three polyps were identified. CONCLUSIONS: At present, the introduction of multislice technology in virtual colonoscopy permits to improve spatial resolution and image definition. The actual clinical advantage, in terms of increased diagnostic accuracy, needs further investigation in larger clinical studies.

Multiphase multislice spiral CT for liver assessment: optimization in cirrhotic patients.

PURPOSE: The aim of our study was to optimize a multiphase study protocol with double arterial phase acquisition in a patient population with cirrhosis using a multislice spiral CT scanner. MATERIAL AND METHODS: Thirteen patients (10 males, 3 females, mean age 58 years) with known cirrhosis were selected for the study. All examinations were performed with a multislice spiral CT scanner (Somatom Plus 4 Volume Zoom; Siemens, Erlangen, Germany). Images were acquired using the following parameters: slice collimation, 2.5 mm; slice thickness, 3.0 mm; table feed, 10.8 mm/sec; mAs, 165; kVp, 120. Four scans of the hepatic parenchyma were obtained after the administration of contrast material. The first pass (early arterial phase) was acquired in a cranio-caudal direction; the second pass (late arterial phase) was acquired in a caudo-cranial direction. Early and late arterial phases were obtained during a single breath-hold of 24 sec. The third pass (portal-venous phase) was acquired with a 60-sec delay time after contrast material injection. The fourth pass (equilibrium phase) was obtained with a 180-sec delay time. Optimal delay time to start CT acquisition was assessed by means of injecting a 20-ml minibolus of contrast material and by performing serial dynamic scans every two sec at the level of the hepatic hilum. The time of peak aortic enhancement was used as the start time for the early arterial phase. Attenuation values of aorta, portal vein, and liver parenchyma were calculated in all the acquisitions. CT data from the early arterial phase were used to produce three-dimensional angiographic images of the hepatic and mesenteric circulation. RESULTS: The enhancement of liver parenchyma progressively increased from pre-contrast phase to portal-venous and equilibrium phases. The highest difference in attenuation values between aorta and hepatic parenchyma was observed during the second acquisition (early arterial phase, 247.78+/-106.29 HU) rather than during the third acquisition (late arterial phase, 185.72+/-109.23 HU); this difference was statistically significant (p<0.01). DISCUSSION: Results from our study emphasize the potential of multiphase acquisition in the evaluation of cirrhotic patients; in particular, the use of an early arterial phase is useful for studying the hepatic and mesenteric vascular anatomy, whereas the late arterial and the portal-venous phases are of paramount importance for adequate evaluation of liver parenchyma and focal lesions. Further studies are needed to evaluate whether the benefits deriving from double arterial phase acquisition would justify the increase in cost and patient radiation exposure.

Randomized clinical trial of intravenous magnesium sulfate as an adjunctive medication for emergency department treatment of migraine headache.

STUDY OBJECTIVE: We test the hypothesis that intravenous magnesium sulfate is an effective adjunctive medication for treatment of acute migraine. METHODS: In this randomized, double-blind, placebo-controlled trial, adults presenting to 2 urban emergency departments with headache meeting International Headache Society criteria for acute migraine received either 20 mg of intravenous metoclopramide plus 2 g of intravenous magnesium sulfate or 20 mg of intravenous metoclopramide plus a placebo of intravenous saline solution at 15-minute intervals for a maximum of 3 doses or until pain relief occurred. At 0, 15, 30, and 45 minutes, patients recorded pain intensity using a standard visual analog scale (VAS). The primary study end point was the between-group difference in pain improvement when initial and final VAS scores were compared. RESULTS: Of 44 patients enrolled (21 randomized to metoclopramide plus magnesium and 23 to metoclopramide plus placebo), 42 (95%) were women. Baseline features were comparable in both groups. Each group experienced a more than 50-mm improvement in VAS score during the study. However, this improvement was smaller in the magnesium group for the primary end point (16-mm difference favoring placebo [95% confidence interval (CI) -2 to 34 mm]), as was the proportion with normal functional status at their final rating (36% absolute difference also favoring placebo [95% CI 7% to 65%]). Using a 50% reduction in pain to dichotomize VAS scores, the number needed to harm with magnesium plus metoclopramide versus metoclopramide alone is 4 patients (95% CI 2 to 36). CONCLUSION: Although this result was unexpected, our data suggest that the addition of magnesium to metoclopramide may attenuate the effectiveness of metoclopramide in relieving migraine. Countertherapeutic cerebral vasodilatation caused by magnesium is a plausible, although unproven, explanation for this finding. Because of the preponderance of women in our trial, these data may not be generalizable to men.

Computed tomographic colonography (virtual colonoscopy): blinded prospective comparison with conventional colonoscopy for the detection of colorectal neoplasia.

BACKGROUND AND STUDY AIMS: Computed tomographic colonography (CTC), also known as virtual colonoscopy, is a recently introduced imaging modality for the detection of colorectal neoplasia. The aim of our study was to evaluate the performance of CTC in a blinded comparison with conventional colonoscopy. PATIENTS AND METHODS: A total of 66 consecutive, symptomatic patients underwent spiral computed tomography (CT) examination after standard bowel preparation. CT images were analyzed and subsequently compared with conventional colonoscopy findings. RESULTS: Conventional colonoscopy detected 15 colorectal carcinomas and 52 polyps. CTC correctly identified all carcinomas, 13 of 14 polyps greater than 10.0 mm (sensitivity 92.8 %; 95 % confidence interval (95 % CI); 77 - 100), 11 of 13 polyps between 6.0 and 9.0 mm (sensitivity 84.6 %; 95 % CI; 62 - 100), and six of 25 polyps smaller than 5.0 mm (sensitivity 24 %; 95 % CI; 6 - 42). The per-patient sensitivity and specificity were 93.7 % and 94.1 %, respectively. CONCLUSIONS: Computed tomographic colonography is an accurate imaging modality for the detection of colorectal neoplasia, especially for lesions larger than 6.0 mm in diameter.

Six-hour versus 12-hour protocols for AMI: CK-MB in conjunction with myoglobin.

The objective was to test the hypothesis that a protocol using myoglobin and creatine kinase-MB (CK-MB) can rapidly and safely exclude myocardial infarction (MI). The study used a prospective, convenience cohort of ED patients with clinically suspected myocardial ischemia. Myoglobin was measured on presentation, 2 and 6 hours later; CK-MB was measured on presentation, 6, 12, and 18 hours later. Of 519 patients, 76 (15%) had MIs, all of whom "ruled in" within 12 hours using a combination of myoglobin and CK-MB, for a sensitivity of 100% (95% CI, 95% to 100%), specificity of 92% (95% CI, 89% to 94%), LR (+) of 12 (95% CI, 9 to 16), and an LR (-) of 0.03 (95% CI, 0.0 to 0.05). Of the 76 patients with MIs, 73 ruled in with a 6 hour protocol, also using a combination of CK-MB and myoglobin, for a sensitivity of 96% (95% CI, 89% to 99%), specificity of 92% (95% CI, 89% to 94%), LR (+) of 11 (95% CI, 8 to 16), and an LR (-) of 0.04 (95% CI, 0.01 to 0.12). Our results support the hypothesis that, using an abbreviated protocol with CK-MB and myoglobin, MI can be reliably ruled out in ED patients with suspected ischemia.

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.