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Purpose: We evaluated the rate of significant colonic and extra-colonic abnormalities at computed tomography colonography (CTC), according to symptoms and age. Materials and methods: We retrospectively evaluated 7361 consecutive average-risk subjects (3073 males, average age: 60.3 ± 13.9; range 18–96 years) for colorectal cancer (CRC) who underwent CTC. They were divided into three groups according to clinical symptoms: 1343 asymptomatic individuals (group A), 899 patients with at least one “alarm” symptom for CRC, including rectal bleeding and unexplained weight loss (group C), and 5119 subjects with other gastrointestinal symptoms (group B). Diagnostic and test-positive rates of CTC were established using optical colonoscopy (OC) and/or surgery as reference standard. In addition, clinically significant extra-colonic findings were noted. Results: 903 out of 7361 (12%, 95% confidence interval (CI) 0.11–0.13) subjects had at least one clinically significant colonic finding at CTC. CTC true positive fraction and false positive fraction were respectively 637/642 (99.2%, 95%CI 0.98–0.99) and 55/692 (7.95%, 95%CI 0.05–0.09). The pooled test-positive rate in group C (138/689, 20.0%, 95%CI 0.17–0.23) was significantly higher than in both groups A (79/1343, 5.9%, 95%CI 0.04–0.07) and B (420/5329, 7.5%, 95%CI 0.07–0.08) (p

The purpose of this study was to assess the feasibility and accuracy of accelerated free-breathing and breath-hold gadolinium-enhanced MR angiography of the main renal arteries compared with digital subtraction angiography.Renal MR angiograms and catheter angiograms of 47 patients (19 men, 28 women; mean age, 68.1 +/- 15.1 years; range, 28-86 years) were reviewed. Thirty-one of the patients underwent free-breathing and 16 underwent breath-hold MR angiography with the same accelerated multiphase imaging protocol. Images were analyzed for examination quality, percentage narrowing of the main renal artery, and visibility of the branches. Diagnostic values of MR angiography were calculated with catheter angiography as the standard of reference.Sixty-five arteries, 24 of which (37%) had49% narrowing, were evaluated in the free-breathing group, and 37 arteries, six of which (16%) had49% narrowing, were evaluated in the breath-hold group. Comparison with digital subtraction angiography showed 100% (24/24) sensitivity and 95% (39/41) specificity for49% renal artery stenosis and 88% sensitivity (15/17) and 100% (48/48) specificity for74% renal artery stenosis in the free-breathing group. In the breath-hold group, sensitivity was 100% (6/6) and specificity 97% (30/31) for49% renal artery stenosis, and sensitivity was 100% (5/5) and specificity 100% (32/32) for74% renal artery stenosis. None of the examinations was nondiagnostic for the main renal arteries, but a smaller number of visible arterial tree subdivisions were found in the free-breathing group (average, 3.64 per patient) than in the breath-hold group (average, 5.87 per patient) (p = 0.035).Like breath-hold examinations, accelerated free-breathing MR angiographic examinations are feasible and accurate in evaluation of the main renal arteries.

Sinusoidal capillarization induces microcirculatory changes in liver cirrhosis and fibrosis. The purpose of this study was to assess whether contrast-enhanced MRI can be used to demonstrate the effects of sinusoidal capillarization in liver fibrosis. Dynamic MRI after injection of a low-molecular-weight contrast agent of 0.56 kDa (Gd-DOTA), and two high-molecular-weight contrast agents of 6.47 kDa and 52 kDa (P792 and P717) was performed in rabbits with liver fibrosis induced by cholesterol and diethylstilbestrol. The hepatic distribution volume accessible to the high-molecular-weight agents decreased in the rabbits with liver fibrosis (P792: 7.8% +/- 1.7% vs. 10.1% +/- 1.8% in normal rabbits, P =.038; P717: 6.2% +/- 2.1% vs. 9.7% +/- 1.6% in normal rabbits, P =.007), whereas the hepatic mean transit time (MTT) of the low-molecular-weight agent was increased (15.9 +/- 8.0 s vs. 8.8 +/- 2.6 s in normal rabbits, P =.015). In rabbits with liver fibrosis, the clearance of indocyanine green (ICG) was correlated with the volume accessible to the high-molecular-weight agents (P792: r = 0.810, P =.015; P717: r = 0.857, P =.007). The collagen content of the liver was inversely correlated with the distribution volume of P717 (r = -.833, P =.010) and with the ICG clearance (r = -.810, P =.015). It was concluded that the microcirculatory changes induced by sinusoidal capillarization in liver fibrosis can be demonstrated noninvasively with MRI.

Quantification of hepatic perfusion parameters greatly contributes to the assessment of liver function. The purpose of this study was to describe and validate the use of dynamic MRI for the noninvasive assessment of hepatic perfusion parameters. The signal from a fast T(1)-weighted spoiled gradient-echo sequence preceded by a nonslice-selective 90 degrees pulse and a spoiler gradient was calibrated in vitro with tubes filled with various gadolinium concentrations. Dynamic images of the liver were obtained after intravenous bolus administration of 0.05 mmol/kg of Gd-DOTA in rabbits with normal liver function. Hepatic, aortic, and portal venous signal intensities were converted to Gd-DOTA concentrations according to the in vitro calibration curve and fitted with a dual-input one-compartmental model. With MRI, hepatic blood flow was 100 +/- 35 mL min(-1) 100 mL(-1), the arterial fraction 24 +/- 11%, the distribution volume 13.0 +/- 3.7%, and the mean transit time 8.9 +/- 4.1 sec. A linear relationship was observed between perfusion values obtained with MRI and with radiolabeled microspheres (r = 0.93 for hepatic blood flow [P < 0.001], r = 0.79 for arterial blood flow [P = 0.01], and r = 0.91 for portal blood flow [P < 0.001]). Our results indicate that hepatic perfusion parameters can be assessed with dynamic MRI and compartmental modeling.

Background Most series that report the results of surgical treatment for congenital liver cysts focus more on the technical aspects of the operation than on the late outcome of these patients. In this paper, we emphasize the importance of appropriate patient selection and adequate surgical technique for successful long-term outcome.

OBJECTIVE: The aim of our study was to determine if hepatic perfusion parameters measured with CT change in relation to disease severity in patients with chronic liver disease. SUBJECTS AND METHODS: Dynamic contrast-enhanced single-section CT scans of the liver were obtained in 40 individuals who included six control subjects, 16 patients with noncirrhotic chronic liver disease, and 18 patients with cirrhosis. Hepatic, aortic, and portal venous time-density curves were fitted to a dual-input one-compartment model to calculate the liver perfusion, arterial fraction, distribution volume, and mean transit time. RESULTS: Liver perfusion decreased in patients with cirrhosis (67 +/- 23 mL. min(-1). 100 mL(-1) versus 108 +/- 34 mL. min(-1). 100 mL(-1) in control subjects [p = 0.009] and 98 +/- 36 mL. min(-1). 100 mL(-1) in patients with noncirrhotic chronic liver disease [p = 0.003]), and the arterial fraction and the mean transit time increased (41 +/- 27% and 51 +/- 79 sec versus 17 +/- 16% and 16 +/- 5 sec in control subjects, and 19 +/- 6% and 17 +/- 8 sec in patients with noncirrhotic chronic liver disease [p < 0.05]). A significant correlation was seen between these three perfusion parameters and the severity of chronic liver disease based on clinical and biologic data (p < 0.001). No significant change in distribution volume was observed. CONCLUSION: Hepatic perfusion parameters measured with CT were significantly altered in cirrhosis and correlated with the severity of chronic liver disease.

The purpose of this study was to compare in the same patients tailored and fixed scanning delays during gadolinium-enhanced arterial-phase magnetic resonance imaging of hypervascular liver tumors. Tailored scanning delays were obtained with automated region of interest threshold triggering. A delay of 23 seconds between the start of contrast material injection and imaging was used for fixed delay examinations. Quantitative and qualitative evaluation was performed in 21 patients with normal cardiac function referred for MR assessment of hypervascular liver tumors. In the tailored examinations, the median time delay between the start of contrast material injection and the start of magnetic resonance imaging was 21 seconds (range, 18-34 seconds). The median tumor-to-liver contrast during tailored examinations was 19.1 versus 14.7 during fixed delay examinations. This difference, however, was not significant. Similarly, the enhancement in the aorta, the portal vein, the liver, and the tumor did not differ significantly between examinations performed with tailored and fixed delays. It is concluded that in our group of patients with hypervascular liver tumors and normal cardiac function, no significant improvement in tumor-to-liver contrast and enhancement during the arterial phase was found when gadolinium-enhanced magnetic resonance imaging was performed with a tailored scanning delay rather than with a fixed delay.

PURPOSE: The purpose of this work was to assess the natural course of biopsy-proven focal nodular hyperplasia (FNH). METHOD: Eighteen biopsy-proven FNHs in 14 patients (12 women and 2 men) who were followed for at least 6 months with CT and/or MRI were included in the study. The volume of the lesions was calculated twice by two observers using the summation of areas method. Intra- and interobserver variability was assessed by intraclass correlation coefficients. Longitudinal data analysis was performed with generalized estimating equations. RESULTS: The volume of FNH was stable in 6 cases, decreased in 10 cases, and increased in 2 cases. Intra- and interobserver variability in size measurements was 5-10%. Intraclass correlation coefficients were >0.992. Longitudinal data analysis showed that there was a general trend of lesion regression. CONCLUSION: Long-term follow-up and objective measurements performed in patients with biopsy-proven lesions show that the natural course of FNH is variable. In particular, lesion regression is not rare.

To analyze the optimal timing strategy for the detection of hypervascular liver tumors during the arterial phase of magnetic resonance (MR) imaging, a test examination after injection of 2 mL of gadopentetate dimeglumine was performed in 47 patients. The time course of the tumor-to-liver contrast-to-noise ratio (CNR) for all studies together was determined relative to the start of injection, the time of peak aortic enhancement, and the time of peak enhancement in the tumor. All studies were grouped together and the highest CNR was transiently observed at the time of peak tumor enhancement. This CNR was significantly higher than those observed at fixed delays after peak aortic enhancement. However, the CNRs at peak tumor enhancement+/-1.5 seconds did not differ significantly from those obtained after peak aortic enhancement. Finally, the CNRs obtained at fixed delays after the start of injection remained significantly lower. In hypervascular liver tumors, a higher CNR can be obtained during the arterial phase when the MR imaging delay is determined relative to the time of peak enhancement in the tumor or the aorta rather than being fixed after the start of contrast material injection. Timing based on the enhancement profile in the tumor rather than in the aorta should be performed only if rapid MR imaging is available with a time resolution of about 1.5 seconds to image the whole liver.

The ileocecal valve sits at the confluence between the terminal ileum and the colon and may thus be involved by number of pathologies linked to these two entities.

Pancreaticopleural fistula secondary to chronic pancreatitis is a rare cause of recurrent pleural effusion. The demonstration of the fistula with endoscopic retrograde pancreatography and CT is invasive or limited. We report in two patients the use of magnetic resonance pancreatography as a noninvasive alternative to endoscopic retrograde pancreatography for the diagnosis of pancreaticopleural fistula.

To prospectively evaluate the learning curves and reading times of inexperienced readers who used the virtual dissection reading method for retrospective computed tomographic (CT) colonography data sets, with and without concurrent computer-aided detection (CAD).An Institutional Review Board approved this study; informed consent was waived. Four radiologists without experience in CT colonography evaluated 100 optical colonoscopy-proved data sets of 100 patients (49 men, 51 women; mean age, 59 years +/- 13 [standard deviation]; range, 21-85 years) by using the virtual dissection reading method. Two readers used concurrent CAD. Data sets were read during five consecutive 1-day sessions (20 data sets per session). Polyp detection and false-positive rates, receiver operating characteristics (ROCs), and reading times were calculated for individual, CAD group, and non-CAD group readings. Diagnostic values were compared by calculating the 95% confidence intervals (CIs) around the relative risk. Areas under ROC curves (AUCs) (Hanley and McNeil for paired analysis and z statistics for unpaired analysis) and reading times (Wilcoxon signed rank test) were compared across the sessions, within each session and for the whole study.The range of detection rates was 79 of 111 (.71 [95% CI: .61, .79]) to 91 of 111 (.82 [95% CI: .73, .88]). The range of false-positive rates was 17 of 111 (.15 [95% CI: .09, .23]) to 22 of 111 (.20 [95% CI: .12, .28]). All readers' AUCs rose from session 1 to session 4; this rise was significant (P.05) for the non-CAD group. Only during session 1 was the CAD group AUC (.83) higher than the non-CAD group AUC (.54) (P.05). Comparison of CAD and non-CAD reading times showed no significant difference for the whole study or during each session (P.05).The virtual dissection reading technique allows short learning curves, which may be improved by the concurrent use of CAD, without significant effect on average reading time.

To determine the correlations between hemodynamic parameters of hepatic flow measured with magnetic resonance (MR) imaging and Doppler ultrasonography (US) and the severity of cirrhosis and portal hypertension.Forty-six patients referred for measurements of portal venous pressure (three with normal liver, 12 with chronic hepatitis, and 31 with cirrhosis [10 with Child-Pugh class A cirrhosis; 13 with class B cirrhosis; and eight with class C cirrhosis]) were included in the study. Apparent liver perfusion, apparent arterial and portal perfusion, portal fraction, distribution volume, and mean transit time were measured with dynamic contrast material-enhanced MR imaging. Portal velocity, portal flow, congestion index, right hepatic artery resistance index, and modified hepatic index were measured with Doppler US. Results in patients with cirrhosis and those without cirrhosis were compared with the Wilcoxon rank sum test. Correlations were assessed with Spearman rank correlation coefficients.With MR imaging, all flow parameters except distribution volume were significantly different between patients with and those without cirrhosis (P.05). There was a significant correlation between all flow parameters measured with MR imaging and portal pressure (P.02). Apparent arterial (P =.024) and portal (P.001) perfusion, portal fraction (P.001), and mean transit time (P =.004) were correlated with Child-Pugh class. Flow parameters measured with Doppler US did not differ significantly between patients with and those without cirrhosis. Only right hepatic arterial resistance (P.007) and portal flow (P.043) were weakly (r0.7) correlated with portal pressure. No Doppler US parameter was correlated with Child-Pugh class.Hepatic flow parameters measured with MR imaging correlate with the severity of cirrhosis and portal hypertension. Doppler US parameters are only weakly correlated with portal pressure.

Interstitial collagen formation and transformation of the fenestrated hepatic sinusoids into continuous capillaries are major ultrastructural changes that occur in liver cirrhosis and fibrosis. These modifications lead to progressive restriction of blood–liver exchanges. The purpose of our study was to evaluate the permeability changes in a model of hepatic fibrosis by using dynamic computed tomography (CT) enhanced with contrast agents of different molecular masses. Dynamic single-section CT of the liver was performed after intravenous bolus administration of a low-molecular-mass contrast agent (iobitridol) and an experimental high-molecular-mass agent (P840) in normal control rabbits and in rabbits with hepatic fibrosis. Hepatic, aortic and portal venous time–density curves were fitted with a dual-input one-compartmental model to calculate the hepatic mean transit time and distribution volume of the contrast agents. In the rabbits with liver fibrosis, the mean transit time of the high-molecular-mass agent was shorter than that of the low-molecular-mass agent (10.0±1.8s and 12.0±1.2s respectively; P

PURPOSE: To assess dual-detector spiral CT arthrography in the evaluation of the entire knee cartilage obtained from cadavers. MATERIALS AND METHODS: Two independent observers characterized articular cartilage in 12 cadaver knees in which MR imaging and dual-detector spiral CT arthrography were performed and compared their findings to those found during macroscopic assessment. The sensitivity and specificity of MR imaging and spiral CT arthrography for detecting grade 2A or higher and grade 2B or higher cartilage lesions, the Spearman correlation coefficient between arthrographic and macroscopic grading, and kappa statistics for assessing interobserver reproducibility were determined. RESULTS: At spiral CT arthrography, sensitivities and specificities ranged between 80% and 88% for the detection of grade 2A or higher cartilage lesions and ranged between 85% and 94% for the detection of grade 2B or higher cartilage lesions. At MR imaging, sensitivities and specificities ranged between 78% and 86% and between 76% and 91% for the detection of grade 2A or higher and grade 2B or higher cartilage lesions, respectively. Spearman correlation coefficients between spiral CT arthrography or MR imaging and macroscopic grading of articular surfaces were 0.797 and 0.702, respectively. CONCLUSION: Dual-detector spiral CT arthrography of the knee is a valuable method for the assessment of open cartilage lesions of the entire knee.

Computed tomography (CT) is used increasingly to measure liver volume in patients undergoing evaluation for transplantation or resection. This study is designed to determine a formula predicting total liver volume (TLV) based on body surface area (BSA) or body weight in Western adults. TLV was measured in 292 patients from four Western centers. Liver volumes were calculated from helical computed tomographic scans obtained for conditions unrelated to the hepatobiliary system. BSA was calculated based on height and weight. Each center used a different established method of three-dimensional volume reconstruction. Using regression analysis, measurements were compared, and formulas correlating BSA or body weight to TLV were established. A linear regression formula to estimate TLV based on BSA was obtained: TLV = -794.41 + 1,267.28 x BSA (square meters; r(2) = 0.46; P < .0001). A formula based on patient weight also was derived: TLV = 191.80 + 18.51 x weight (kilograms; r(2) = 0.49; P < .0001). The newly derived TLV formula based on BSA was compared with previously reported formulas. The application of a formula obtained from healthy Japanese individuals underestimated TLV. Two formulas derived from autopsy data for Western populations were similar to the newly derived BSA formula, with a slight overestimation of TLV. In conclusion, hepatic three-dimensional volume reconstruction based on helical CT predicts TLV based on BSA or body weight. The new formulas derived from this correlation should contribute to the estimation of TLV before liver transplantation,or major hepatic resection.

OBJECTIVE: The purpose of this study was to assess the improvement in the detection of ureteral stones on abdominal radiographs when the stones were viewed on multislice helical CT scans and maximum-intensity-projection (MIP) images. SUBJECTS AND METHODS: The study included 72 patients with renal colic who underwent abdominal radiography and multislice helical CT. For each patient, a frontal MIP image was generated, and the stone, when present, was marked with a cross on the transverse CT scan. The cross appeared automatically on the corresponding MIP image. The CT examination was used as the standard of reference. The presence and location of ureteral stones on the abdominal radiographs were assessed during three interpretation sessions. In the first session, the abdominal radiographs were viewed alone. In the second, they were viewed with the transverse CT scans. In the third, the abdominal radiographs were viewed with the CT scans and the MIP images. RESULTS: Ureteral stones were present in 58 patients. The percentage of stones detected on the abdominal radiographs was 45% when the radiographs were viewed alone, 66% when they were viewed with the CT scans (p = 0.002 vs radiographs alone), and 78% when viewed with the CT scans and MIP images (p = 0.016 vs radiographs with CT scans). CONCLUSION: The sensitivity of stone detection on abdominal radiographs was greatest when the interpreters viewed the radiographs in conjunction with the CT scans and MIP images.

Ferumoxtran, an ultrasmall superparamagnetic iron oxide particle, can be located in several tissue compartments in the liver, namely the extracellular space (blood and interstitium), reticuloendothelial cells, and possibly hepatocytes. To better understand the compartmental distribution of ferumoxtran in the liver, we performed a longitudinal study in the rat using microscopy and magnetic resonance imaging. At light microscopy, no substantial cellular uptake of ferumoxtran was observed before one hour after injection. With a dose of 15 micromol Fe/kg, the number of ferumoxtran particles in the reticuloendothelial cells peaked between one and four hours and with a 150 micromol Fe/kg dose, it peaked between eight and 24 hours. Within hepatocytes, only sparse particles were observed with electron microscopy, at a dose of 150 micromol Fe/kg. Imaging performed up until one hour after ferumoxtran injection showed a significant increase in liver signal intensity on T1-weighted images. These results suggest that ferumoxtran mainly acts as an extracellular agent for at least one hour in the rat and that reticuloendothelial accumulation peaks at later time points. Substantial uptake within hepatocytes did not occur.

Disease-modifying genes might participate in the significant intrafamilial variability of the renal phenotype in autosomal dominant polycystic kidney disease (ADPKD). Cystic fibrosis (CF) transmembrane conductance regulator (CFTR) is a chloride channel that promotes intracystic fluid secretion, and thus cyst progression, in ADPKD. The hypothesis that mutations of the CF gene, which encodes CFTR, might be associated with a milder renal phenotype in ADPKD was tested. A series of 117 unrelated ADPKD probands and 136 unaffected control subjects were screened for the 12 most common mutations and the frequency of the alleles of the intron 8 polymorphic TN: locus of CF. The prevalence of CF mutations was not significantly different in the ADPKD (1.7%, n = 2) and control (3.7%, n = 5) groups. The CF mutation was DeltaF508 in all cases, except for one control subject (1717-1G A). The frequencies of the 5T, 7T, and 9T intron 8 alleles were also similar in the ADPKD and control groups. Two additional patients with ADPKD and the DeltaF508 mutation were detected in the families of the two probands with CF mutations. Kidney volumes and renal function levels were similar for these four patients with ADPKD and DeltaF508 CFTR (heterozygous for three and homozygous for one) and for control patients with ADPKD collected in the University of Colorado Health Sciences Center database. The absence of a renal protective effect of the homozygous DeltaF508 mutation might be related to the lack of a renal phenotype in CF and the variable, tissue-specific expression of DeltaF508 CFTR. Immunohistochemical analysis of a kidney from the patient with ADPKD who was homozygous for the DeltaF508 mutation substantiated that hypothesis, because CFTR expression was detected in 75% of cysts (compared with

BACKGROUND AND STUDY AIMS: The aim of this study was to compare prospectively the diagnostic efficacy of magnetic resonance (MR) imaging and endoscopic ultrasonography (EUS) in extrahepatic biliary obstruction. PATIENTS AND METHODS: A total of 50 patients with suspected benign or malignant extrahepatic biliary obstruction underwent MR imaging, including MR cholangiopancreatography, and EUS, within a median time delay of 1 day. The final diagnosis was established by endoscopic retrograde cholangiopancreatography in 37 cases, intraoperative cholangiography in nine cases, and clinical and biochemical follow-up in four cases. RESULTS: In total, 33 patients had extrahepatic biliary obstruction, of benign origin in 21 cases and of malignant origin in 12 cases, whereas 17 had no evidence of obstruction. The sensitivity and specificity of MR imaging were 91% and 94 %, respectively. There were one false-positive and three false-negative results, all related to choledochal sludge. The corresponding values for EUS were 97% and 88%. There were two false-positive results and one false-negative result. False-positive diagnoses were related to the presumed presence of biliary sludge and choledocholithiasis, whereas the false-negative diagnosis occurred in one patient with a final diagnosis of sludge. No significant difference in sensitivity and specificity was observed between the two imaging methods (P>0.05). CONCLUSION: In our study MR imaging was as accurate as EUS in the diagnosis of extrahepatic biliary obstruction.

Objectifs Connaitre les aspects normaux et pathologiques de la valvule de Bauhin. Faire le diagnostic differentiel des stenoses circonferencielles. Differencier les selles compactes des polypes. Points cles Une bonne preparation et une distension optimales sont necessaires pour contourner les pieges diagnostiques communs. L’identification de la valvule de Bauhin est indispensable pour ne pas risquer de meconnaitre de petites lesions tumorales a son niveau ou dans son voisinage immediat. Les stenoses circonferentielles peuvent etre causees par un cancer, un spasme, une inflammation ou une infiltration tissulaire sous-muqueuse. L’observation comparative de la forme et de la position des protrusions endo-luminales permet generalement de distinguer les selles compactes et adherentes des polypes. Resume A l’etat normal, il existe de grandes variations dans le degre d’infiltration lipomateuse de la valvule de Bauhin. Elle doit cependant conserver un aspect harmonieux et symetrique. Une formation nodulaire sur une valvule fine ou une plage tissulaire dans une valvule lipomateuse doivent faire evoquer un processus tumoral. En cas de decouverte d’une stenose circonferentielle, les tumeurs presentent generalement un caractere asymetrique et abrupt ; les spasmes sont symetriques et souvent retrouves a un niveau discretement different dans les 2 acquisitions ; les stenoses inflammatoires contiennent souvent un diverticule et sont generalement symetriques ; les infiltrations sous-muqueuses, comme l’endometriose peuvent determiner une stenose harmonieuse et constante dans les 2 acquisitions. Dans tous les cas, a l’exception du spasme, il peut exister une infiltration de la graisse avoisinante. Par rapport aux polypes, les selles compactes et adherentes presentent souvent des contours geometriques ou irreguliers dont la forme peut discretement se modifier dans les 2 acquisitions. De meme, leur position varie souvent discretement.

Objectifs Les travaux des ces dernieres annees ont largement valide la colonoscopie virtuelle en terme de diagnostic des tumeurs et polypes de taille significative. La large diffusion des scanners multibarrettes et des softwares specifiques de lecture permet d’envisager la realisation de CV en pratique courante : quelques sugestions d’organisation pratique. Resume 1. Suivre des cours specifiques : p. E., ceux de l’ESGAR, assurant les connaissances theoriques et l’apprentissage de la lecture, preferentiellement sur la console de travail habituellement utilisee. 2. Preparation colique : au debut de la pratique, il est plus facile de lire des colons parfaitement propres. Envisager le « tagging » plus tard si l’on opte pour une lecture 2D. 3. Technique : coupes fines, low dose, CO2. 4. Indications : celles du lavement baryte, a l’exclusion des maladies inflammatoires. 5. Interpretation : dans la foulee, ce qui permet la resection d’eventuels polypes sans nouvelle preparation. 6. Diffuser l’information : rencontre avec le patient apres l’examen et explications sur le depistage, presentations orales dans l’hopital, articles dans les revues medicales locales, poster dans la salle d’attente, exposes aupres des generalistes, envoi d’une copie du rapport et des images (sur papier couleur) au generaliste … 7. Continuer sa formation : conserver un CD pour relecture en cas de faux negatif de la CV. Conclusion Avec de l’experience, la CV est un examen simple et rapide, et il est parfaitement possible de l’integrer dans une consultation de routine : c’est un premier pas vers la validation officielle de cette technique dans le depistage du cancer colo-rectal.

Objectifs Connaitre le necessaire et suffisant pour se lancer. Apprendre comment organiser la consultation. Apprendre a optimiser le compte-rendu. Apprendre comment faire connaitre la technique aux prescripteurs et aux patients. Messages a retenir Il suffit d’un scanner multibarrettes, d’un logiciel dedie et d’un radiologue experimente pour debuter la consultation. Le radiologue doit dispenser a son secretariat une information sur les differentes preparations coliques et leurs indications et etre lui-meme disponible pour les questions des patients. La lecture de l’examen doit etre immediate pour permettre une eventuelle resection endoscopique dans la foulee. Le compte-rendu doit detailler la technique, la preparation et le diagnostic doit s’accompagner de recommandations de suivi. Des presentations et des publications locales permettent de faire connaitre cette technique et de convaincre de ses performances. Les medecins de famille sont souvent les premiers interesses. Resume Il est techniquement facile d’implementer une consultation de colonoscopie virtuelle, mais la reussite est au prix d’un investissement personnel important du radiologue tant pour sa propre formation que pour la promotion de la technique, longtemps controversee et qui reste a ce jour encore peu utilisee.

Objectifs Comprendre le principe du CAD. Connaitre ses performances et ses limitations. Apprendre a limiter le nombre de faux positifs. Apprendre son utilite en phase d’apprentissage et en pratique courante. Messages a retenir Le CAD detecte les protrusions endoluminales arrondies (polypes et residus), sa sensibilite dependra du rayon de courbure choisi. Tous les systemes commercialises ont au moins une sensibilite de 95% mais sont peu performants dans la detection des lesions planes. Ils peuvent etre utilises simultanement ou en deuxieme lecture. Le nombre de faux positifs sera d’autant plus important que les lesions recherchees seront petites et que le colon sera mal prepare. Le CAD ameliore la detection de tous les lecteurs, quel que soit leur niveau d’experience mais n’influence pas la caracterisation. Resume En facilitant la detection des candidats-polypes, principale difficulte des debutants, le CAD ameliore la courbe d’apprentissage. Il ne sera malheureusement d’aucune utilite pour la caracterisation des lesions potentielles et est peu performant pour les lesions planes.

Objectifs pedagogiques Apprendre comment se constitue l’image d’auto-dissection. Comprendre la cause des deformations anatomiques qui en resultent. Interpreter les images.

Various liver diseases lead to significant alterations of the hepatic microcirculation. Therefore, quantification of hepatic perfusion has the potential to improve the assessment and management of liver diseases. Most methods used to quantify liver perfusion are invasive or controversial. This paper describes and validates a non-invasive method for the quantification of liver perfusion using computed tomography (CT). Dynamic single-section CT of the liver was performed after intravenous bolus administration of a low-molecular-mass iodinated contrast agent. Hepatic, aortic and portal-venous time—density curves were fitted with a dual-input one-compartmental model to calculate liver perfusion. Validation studies consisted of simultaneous measurements of hepatic perfusion with CT and with radiolabelled microspheres in rabbits at rest and after adenosine infusion. The feasibility and reproducibility of the CT method in humans was assessed by three observers in 10 patients without liver disease. In rabbits, significant correlations were observed between perfusion measurements obtained with CT and with microspheres (r = 0.92 for total liver perfusion, r = 0.81 for arterial perfusion and r = 0.85 for portal perfusion). In patients, total liver plasma perfusion measured with CT was 112±28 ml·min-1·100 ml-1, arterial plasma perfusion was 18±12 ml·min-1·100 ml-1 and portal plasma perfusion was 93±31 ml·min-1·100 ml-1. The measurements obtained by the three observers were not significantly different from each other (P > 0.1). Our results indicate that dynamic CT combined with a dual-input one-compartmental model provides a valid and reliable method for the non-invasive quantification of perfusion in the normal liver.