Natural History of Pneumoperitoneum After Laparotomy: Findings on Multidetector-Row Computed Tomography.

BACKGROUND: Postoperative pneumoperitoneum after abdominal surgery represents a diagnostic challenge. This study was designed to analyze the appearance of pneumoperitoneum on computed tomography after uncomplicated abdominal surgery through laparotomy. METHODS: The database of the department of digestive surgery was retrospectively queried to identify all patients who underwent abdominal surgery through laparotomy during a 13-month period. This initial search retrieved a total of 384 consecutive patients. Criteria for inclusion in this study were: (a) the operation was performed in our institution, (b) the patient had computed tomography examination postoperatively, and (c) the patient had no postoperative grade ≥3 complication. RESULTS: Postoperative pneumoperitoneum was visible in 38/80 patients (47.5 %), with a mean volume of 15 ± 22.8 (SD) cm3 and multiple locations in 32/38 patients (84 %). Postoperative pneumoperitoneum was observed in 22/26 patients (85 %) until day 5 postoperative, 14/34 patients (41 %) between day 6 and day 15 postoperative, and in 2/21 patients (9.5 %) after day 15 postoperative. Its volume decreased when the time interval between surgery and computed tomography increased. Results of multivariate analysis showed that the time interval between surgery and computed tomography was the single independent variable that was associated with the presence of postoperative pneumoperitoneum. CONCLUSIONS: Postoperative pneumoperitoneum is a frequent finding on computed tomography in the early period following abdominal surgery and commonly with multiple locations. Although commonly observed before day 5 postoperative, its presence must be considered as an alarming finding after day 7 postoperative, if present in a single location with a volume >20 cm3.

Diffusion-weighted MR imaging of uterine leiomyomas following uterine artery embolization.

PURPOSE: To test whether variations in apparent diffusion coefficient (ADC) values of uterine leiomyomas after uterine artery embolization (UAE) may correlate with outcome and assess the effects of UAE on leiomyomas and normal myometrium with magnetic resonance imaging (MRI). METHODS: Data of 49 women who underwent pelvic MRI before and after UAE were retrospectively reviewed. Uterine and leiomyoma volumes, ADC values of leiomyomas, and normal myometrium were calculated before and after UAE. RESULTS: By comparison with baseline ADC values, a significant drop in leiomyoma ADC was found at 6-month post-UAE (1.096 × 10(-3) mm(2)/s vs. 0.712 × 10(-3) mm(2)/s, respectively; p < 0.0001), but not at 48-h post-UAE. Leiomyoma devascularization was complete in 40/49 women (82 %) at 48 h and in 37/49 women (76 %) at 6 months. Volume reduction and leiomyoma ADC values at 6 months correlated with the degree of devascularization. There was a significant drop in myometrium ADC after UAE. Perfusion defect of the myometrium was observed at 48 h in 14/49 women (28.5 %) in association with higher degrees of leiomyoma devascularization. CONCLUSION: Six months after UAE, drop in leiomyoma ADC values and volume reduction correlate with the degree of leiomyoma devascularization. UAE affects the myometrium as evidenced by a drop in ADC values and initial myometrial perfusion defect. KEY POINTS: • A drop in leiomyoma ADC values is observed 6 months after UAE. • Drop in leiomyoma ADC value is associated with leiomyoma devascularizarion after UAE. • MR 48 h post-UAE allows assessing leiomyoma devascularization. • Myometrium perfusion defect occurs more often in women with a smaller uterus.

Suspected invasive placenta: evaluation with magnetic resonance imaging.

PURPOSE: To determine the utility of magnetic resonance imaging (MRI) in diagnosing invasive placenta (IP). MATERIALS AND METHODS: MRI findings in 32 women with suspected IP were evaluated independently by four readers. Interobserver agreement was calculated with kappa (κ) statistics. Associations between MRI findings and IP were assessed by univariate and multivariate analyses. Sensitivity, specificity and accuracy of MRI for the diagnosis of IP were estimated. RESULTS: Sixteen women (16/32; 50%) had confirmed IP. Interobserver correlation for the diagnosis of IP was fair (κ = 0.40). Univariate analysis revealed that thinning or focal defect of the uteroplacental interface (P < 0.0001) was the most discriminating MRI variable in the differentiation between normal and IP. Overall sensitivity and specificity of MRI for the diagnosis of IP were 84% [95% CI: 75-94%] and 80% [95% CI: 66-93%], respectively. Thinning or focal defect of the uteroplacental interface was the most accurate finding (88%) in the diagnosis of IP. Multivariate analysis revealed that thinning or focal defect of the uteroplacental interface was the single independent predictor of IP (P = 0.0006; OR = 64.99). CONCLUSION: MR imaging has 84% sensitivity [95% CI: 75-94%] and 80% specificity [95% CI: 66-93%] for the diagnosis of IP. Thinning or focal defect of the uteroplacental interface is the most discriminating independent MR variable in differentiating between normal placenta and IP. KEY POINTS: MR imaging has acceptable degrees of accuracy to diagnose invasive placenta. Focal uteroplacental interface defect is the best finding to diagnose invasive placenta. Focal uteroplacental interface defect is the single independent predictor of invasive placenta.

Diffusion-weighted MR imaging for the diagnosis of abscess complicating fistula-in-ano: preliminary experience.

OBJECTIVE: To investigate the role of diffusion-weighted magnetic resonance imaging (DWMRI) in the diagnosis of abscess-complicating fistula-in-ano. METHODS: This retrospective study was approved by our Institutional Review Board and informed consent was waived. MRI examinations, including fat-suppressed T2-weighted turbo spin-echo (T2-TSE) MRI and DWMRI, of 24 patients with a fistula-in-ano, were reviewed by two independent readers for the presence and number of visible fistulas, conspicuity and apparent diffusion coefficient (ADC) measurement of suspected fistula tracks and pelvic collections. The reference standard was surgical with follow-up findings. RESULTS: Sensitivity was 91.2 % [95 % CI: 76 %-98 %] for T2-weighted TSE MRI and 100 % [95 % CI: 90 %-100 %] for DWMRI detecting fistulas. ADC values were lower in abscesses than in inflammatory masses (P = 0.714.10(-6)). The area under the ROC curve was 0.971 and the optimal cut-off ADC value was 1.186 × 10(-3) mm(2)/s, yielding a sensitivity of 100 % [95 % CI: 77 %-100 %], a specificity of 90 % [95 % CI: 66 %-100 %], a positive predictive value of 93 % [95 % CI: 82.8 %-100 %] and a negative predictive value of 90 % [95 % CI: 78 %-100 %] for an abscess diagnosis. Fistula conspicuity was greater with DWMRI than with T2-TSE MRI for the two observers (P = 0.0034 and P = 0.0007). CONCLUSION: DWMRI shows high sensitivity and specificity for the diagnosis of perianal abscesses and helps discriminate between an abscess and inflammatory mass. Conspicuity of fistulas-in-ano is greater with DWMRI than with T2-weighted TSE MRI. KEY POINTS: • DWMRI can differentiate between pelvic abscess and inflammatory mass. • DWMRI helps avoid gadolinium-chelate administration in patients with a suspected fistula-in-ano. • DWMRI provides high degrees of conspicuity for fistula-in-ano. • Conspicuity of fistulas is better with DWMRI imaging than with T2-TSE-weighted MRI.

Helical CT-enteroclysis in the detection of small-bowel tumours: a meta-analysis.

OBJECTIVE: To perform a meta-analysis to determine sensitivity and specificity estimates of helical CT-enteroclysis in the detection of small-bowel tumours. METHODS: A search for relevant articles published from January 1992 to November 2010 was performed. Study design, patient characteristics and 2 × 2 contingency tables were recorded for eligible studies. Heterogeneity was assessed with the I (2) statistic. A bivariate generalised linear random-effects model was used to summarise sensitivity and specificity estimates for small-bowel tumour detection on a per-patient basis. Sensitivity and specificity estimates were compared in different subgroups. RESULTS: Twelve studies (696 patients) were eligible. The mean small-bowel tumour prevalence was 22.6 % (range 7.7-45.8 %). Inter-study heterogeneity was substantial for sensitivity (I (2) = 66.9 %; 95 % CI 28.7-88.5 %) and low for specificity (I (2) = 10.6 %; 95 % CI 0.0-55.0 %). On a per-patient basis, pooled sensitivity was 92.8 % (95 % CI 71.3-98.5 %) and pooled specificity 99.2 % (95 % CI 94.2-99.9 %) for the diagnosis of small-bowel tumour. Subgroup analysis revealed that small-bowel preparation, more than one imaging pass and large volumes (≥2 L) of enteral contrast agent did not improve tumour detection. CONCLUSION: Our meta-analysis confirms that helical CT-enteroclysis has high degrees of sensitivity and specificity for small-bowel tumour detection. However, our findings reinforce the need for more standardised individual studies.

Hepatic and pancreatic involvement in hereditary hemorrhagic telangiectasia: quantitative and qualitative evaluation with 64-section CT in asymptomatic adult patients.

PURPOSE: To analyse quantitatively and qualitatively asymptomatic hepatic and pancreatic involvement in hereditary haemorrhagic telangiectasia (HHT) using 64-section helical CT. MATERIALS AND METHODS: The 64-section helical CT examinations of 19 patients with HHT (8 men, 11 women; mean age, 58.6 years) were quantitatively and qualitatively analysed and compared to those of 19 control subjects who were matched for age and sex. Comparisons were made using univariate analysis. RESULTS: Dilated and tortuous intrahepatic arterial branches was the most discriminating independent variable (P < 0.0001) and had the highest specificity (100%; 19/19; 95%CI: 82%-100%) and accuracy (97%; 37/38; 95%CI: 86%-100%) for the diagnosis of HHT. Heterogeneous enhancement of hepatic parenchyma, intrahepatic telangiectases, hepatic artery to hepatic vein shunting, hepatic artery enlargement (i.e. diameter > 6.5 mm) and portal vein enlargement (i.e. diameter > 13 mm) were other variables that strongly correlated with the presence of HHT. Intrapancreatic telangiectases and arteriovenous malformations were found in 42% and 16% of patients with HHT, respectively. CONCLUSION: Liver and pancreatic involvement in asymptomatic HHT patients is associated with myriad suggestive findings on 64-section helical CT. It can be anticipated that familiarity with these findings would result in more confident diagnosis of HHT.

Hepatic height on coronal computed tomography images predicts total liver volume in European adults without liver disease.

BACKGROUND: Hepatic volume measurement provides useful information in a large range of clinical situations. AIMS: The goal of this study was to test the hypothesis that significant correlation exists between hepatic volume calculated using three-dimensional reconstruction of computed tomography (CT) data and hepatic height calculated using coronal reformation of CT images in European adult patients without liver disease. METHODS: One hundred patients (50 men, 50 women; mean age, 47 years) without hepatic disease were included. Coronal and three-dimensional images of the liver were obtained using 64-section helical CT. Correlation between hepatic height and hepatic volume was searched for using the Pearson correlation test. Regression analysis was used to compare hepatic height and hepatic volume. RESULTS: A strong and highly significant positive correlation was found between hepatic height and hepatic volume, with a correlation coefficient (r) of 0.767 (95%CI 0.672-0.837; r² = 0.588) (P < 0.001). The equation of the correlation line was y = 11.764x - 244 where y represents the hepatic volume in cm³ and x the hepatic height in mm. CONCLUSION: Hepatic height as obtained on coronal CT image is a simple and rapid measurement that allows predicting hepatic volume in European adult patients without liver disease.

Detection of colorectal tumors with water enema-multidetector row computed tomography.

PURPOSE: To retrospectively determine the diagnostic capabilities of water enema-multidetector row computed tomography (WE-MDCT) in the detection of colorectal tumors. MATERIALS AND METHODS: One hundred and one patients (55 male, 46 female) who had WE-MDCT and videocolonoscopy because of suspected colorectal tumors were included. Results of complete videocolonoscopy, surgery, and histopathologic analysis were used as standard of reference. Sensitivity, specificity, and accuracy, and positive and negative predictive values of WE-MDCT for the diagnosis of colorectal tumors were estimated with 95% confidence intervals (CIs). RESULTS: Ninety-two colorectal tumors (64 malignant, 28 benign) were confirmed in 71 patients (prevalence, 71/101; 70%). Overall sensitivity for colorectal tumor detection was 87% (80/92; 95%CI: 78%-93%) on a per lesion basis. For malignant and benign tumor detection, sensitivity was 100% (64/64; 95%CI: 94%-100%) and 57% (16/28; 95%CI: 37%-76%), respectively. For colorectal tumors ≥10 mm, sensitivity was 99% (76/77; 95%CI: 93%-100%). Seventy-nine of the 83 colorectal tumors ≥6 mm were detected, yielding a sensitivity of 95% (79/83; 95%CI: 88%-99%) for this specific size category. On a per patient basis, WE-MDCT had a sensitivity of 100% (71/71; 95%CI: 94%-100%), a specificity of 100% (30/30; 95%CI: 88%-100%), an accuracy of 100% (101/101; 95%CI: 96%-100%), a positive predictive value of 100% (71/71; 95%CI: 94%-100%), and a negative predictive value of 100% (30/30; 95%CI: 86%-100%) for the diagnosis of colorectal tumor. CONCLUSION: Our results suggest that WE-MDCT is a promising imaging technique for the detection of malignant colorectal tumors. However, our results should be validated by larger and prospective studies.

A pre-operative radiological score to predict lymph node metastasis in advanced epithelial ovarian cancer.

BACKGROUND: Lymphadenectomy is part of cytoreductive surgery for patients with advanced epithelial ovarian cancer (AEOC) in case of abnormal lymph nodes before and during surgery. The aim of this study was to develop and validate a pre-operative radiological score to predict pelvic and/or para-aortic lymph node metastasis (LNM) in patients with AEOC undergoing cytoreductive surgery. METHODS: We conducted a multicentre retrospective study. The construction sample was composed of 53 patients operated within two referral centers. The validation sample was composed of 39 patients operated in a third referral center. The score was built with a logistic regression model with internal validation by bootstrap. RESULTS: Two variables were associated with the prediction of pelvic and/or para-aortic LNM at computerized tomography (CT) and/or positron emission tomography (PET/CT): "para-aortic lymph node involvement" (adjusted diagnostic odds ratio) (aDOR) = 8.77 95CI [1.42-54.09], p = 0.02) and "colon involvement" (aDOR = 7.97 95CI [1.28-49.58], p = 0.03). Bootstrap procedure showed that the model was stable. The 2-points LNM pre-operative radiological score was derived from these 2 radiological variables and a high-risk group was identified for a score ≥ 1: the probability of pelvic and/or para-aortic LNM was 76%, the specificity was 85.7% 95CI [67.3-96.0] and the positive likelihood ratio was 3.6 95CI [1.4-9.7]. In the validation sample, a score ≥ 1 had a specificity of 78.3% and a LR+ of 1.2. CONCLUSION: LNM pre-operative radiological score could help the surgeon's decision to perform pelvic and para-aortic lymphadenectomy in patients with AEOC undergoing cytoreductive surgery. TRIAL REGISTRATION: The research protocol was approved by the Ethics Committee for Research in Obstetrics and Gynecology (CEROG 2016-GYN 1003).

Obscure gastrointestinal bleeding: preliminary comparison of 64-section CT enteroclysis with video capsule endoscopy.

OBJECTIVE: To retrospectively compare the diagnostic capabilities of 64-section CT enteroclysis with those of video capsule endoscopy (VCE) to elucidate the cause of obscure gastrointestinal bleeding. METHODS: Thirty-two patients who had 64-section CT enteroclysis and VCE because of obscure gastrointestinal bleeding were included. Imaging findings were compared with those obtained at double balloon endoscopy, surgery and histopathological analysis, which were used as a standard of reference. RESULTS: Concordant findings were found in 22 patients (22/32; 69%), including normal findings (n=13), tumours (n=7), lymphangiectasia (n=1) and inflammation (n=1), and discrepancies in 10 patients (10/32; 31%), including ulcers (n=3), angioectasias (n=2), tumours (n=2) and normal findings (n=3). No statistical difference in the proportions of abnormal findings between 64-section CT enteroclysis (11/32; 34%) and VCE (17/32, 53%) (P=0.207) was found. However, 64-section CT enteroclysis helped identify tumours not detected at VCE (n=2) and definitely excluded suspected tumours (n=3) because of bulges at VCE. Conversely, VCE showed ulcers (n=3) and angioectasias (n=2) which were not visible at 64-section CT enteroclysis. CONCLUSION: Our results suggest that 64-section CT enteroclysis and VCE have similar overall diagnostic yields in patients with obscure gastrointestinal bleeding. However, the two techniques are complementary in this specific population.

A Pre-operative Score to Discriminate Fibroepithelial Lesions of the Breast: Phyllode Tumor or Fibroadenoma?

BACKGROUND/AIM: Fibroepithelial lesions (FEL) of the breast include fibroadenomas and phyllodes tumors (PT). Their histologic characteristics on core needle biopsy can overlap, while their clinical management is different. The aim of this study was to develop and to validate a pre-operative score for the diagnosis of PT with surgical decision rules. PATIENTS AND METHODS: We developed a pre-operative score for the diagnosis of PT by performing logistic regression on 217 FEL of the Rene Huguenin Hospital. This score and the surgical decision rules were validated on 87 FEL of the Lariboisiere Hospital. RESULTS: Three variables were independently and significantly associated with PT: age ≥40 years, mammography's tumor size ≥3 cm and PT diagnosed by CNB. The pre-operative score was based on these three criteria with values ranging from 0 to 10. Surgical decision rules were created: the low-risk group of PT (score≤2) had a sensitivity of 92.6% and a LR- of 0.2, the high-risk group (score>7) had a specificity of 93.5% and a LR+ of 4.4. In the validation sample, surgical decision rules were applied. CONCLUSION: These surgical decision rules may prove useful in deciding which FEL needs surgical resection.

Small bowel volvulus due to torsion of pedunculated uterine leiomyoma: CT findings.

Torsion of a uterine leiomyoma is a rare complication that can be life threatening because of ischemia or necrosis. This condition may also lead to gastrointestinal complications such as obstruction or, more rarely, small bowel volvulus. Its diagnosis is difficult and can be facilitated with the use of computed tomography or magnetic resonance imaging. Treatment is based on emergency surgical resection of the twisted uterine leiomyoma and detorsion of the small bowel volvulus.

Magnetic resonance imaging features of uterine sarcoma and mimickers.

Uterine myometrial tumors are predominantly benign conditions that affect one-third of women and represent the main indication for hysterectomy. Preoperative imaging is of utmost importance for characterization and for precise mapping of myometrial tumors to best guide therapeutic strategy. New minimally invasive therapeutic strategies including morcellation, myolysis, uterine artery embolization and image-guided radiofrequency or focused ultrasound ablation have been developed for the treatment of uterine leiomyoma. However, preoperative differentiation between atypical leiomyomas and leiomyosarcomas is critical on imaging as uterine sarcoma requires a specific surgical technique to prevent dissemination. A single, rapidly growing uterine tumor, associated with endometrial thickening and ascites, in post-menopausal women is suspicious of uterine endometrial stromal sarcoma and carcinosarcoma. Suggestive magnetic resonance imaging features have been described, but overlap in imaging appearance between uterine leiomyosarcomas and cellular leiomyomas makes it challenging to ascertain the diagnosis. This review aims to illustrate the imaging features of uterine sarcomas and potential mimickers to make the reader more familiar with this serious condition which needs special consideration.

T2-weighted MR imaging of the liver: qualitative and quantitative comparison of SPACE MR imaging with turbo spin-echo MR imaging.

OBJECTIVE: To qualitatively and quantitatively compare T2-weighted MR imaging of the liver using volumetric spin-echo with sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE) with conventional turbo spin-echo (TSE) sequence for fat-suppressed T2-weighted MR imaging of the liver. MATERIALS AND METHODS: Thirty-three patients with suspected focal liver lesions had SPACE MR imaging and conventional fat-suppressed TSE MR imaging. Images were analyzed quantitatively by measuring the lesion-to-liver contrast-to-noise ratio (CNR), and the signal-to-noise ratio (SNR) of main focal hepatic lesions, hepatic and splenic parenchyma and qualitatively by evaluating the presence of vascular, respiratory motion and cardiac artifacts. Wilcoxon signed rank test was used to search for differences between the two sequences. RESULTS: SPACE MR imaging showed significantly greater CNR for focal liver lesions (median=22.82) than TSE MR imaging (median=14.15) (P<.001). No differences were found for SNR of hepatic parenchyma (P=.097), main focal hepatic lesions (P=.35), and splenic parenchyma (P=.25). SPACE sequence showed less artifacts than TSE sequence (vascular, P<.001; respiratory motion, P<.001; cardiac, P<.001) but needed a longer acquisition time (228.4 vs. 162.1s; P<.001). CONCLUSION: SPACE MR imaging provides a significantly increased CNR for focal liver lesions and less artifacts by comparison with the conventional TSE sequence. These results should stimulate further clinical studies with a surgical standard of reference to compare the two techniques in terms of sensitivity for malignant lesions.

Evaluation of symptomatic uterine fibroids in candidates for uterine artery embolization: comparison between ultrasonographic and MR imaging findings in 68 consecutive patients.

Ultrasonographic and magnetic resonance (MR) imaging examinations of 68 women with uterine fibroids were reviewed to determine whether MR imaging may alter the therapeutic approach based on ultrasonography alone before uterine embolization. Therapeutic decisions based on ultrasonography alone were compared to those obtained after MR imaging. Discordant findings between both examinations involved 51 women (75%), and 19 (28%) had their therapeutic approaches based on ultrasonography alone altered by MR imaging. Ultrasonography and MR imaging showed concordant findings in 17 women (25%) for whom no changes in therapeutic option were made. MR imaging alters the therapeutic approach based on ultrasonography alone in 28% of candidates for uterine artery embolization.

Ileal adenocarcinoma in Crohn's disease: magnetic resonance enterography features.

Patients with Crohn's disease are at increased risk for small bowel adenocarcinoma. We report herein two cases of Crohn's disease-related ileal adenocarcinoma, which were investigated by means of magnetic resonance (MR)-enterography. Two different patterns were observed. In one case, the tumor presented as long circumferential, asymmetric and heterogeneous thickening of the ileum with visible nodule on free induction echo stimulated acquisition images. In the other case, the malignant lesion presented as a tumor mass of the terminal ileum, extending onto the cecum, and showed restricted diffusion on diffusion-weighted MR imaging. In both cases, the tumors were diagnosed preoperatively. Histopathological analysis after surgical resection confirmed T4N1 poorly differentiated mucinous adenocarcinoma of the ileum in association with findings consistent with active in one case and inactive Crohn's disease in the other case. Our observations suggest that MR-enterography may be a useful imaging test for the detection of small bowel adenocarcinoma in patients with Crohn's disease.

Small bowel tumors: spectrum of findings on 64-section CT enteroclysis with pathologic correlation.

Improvements in helical technology have made detection of benign and malignant small bowel tumors easier so that they are now frequently detected at an early stage. Sixty-four-section CT enteroclysis provides suggestive features that help determine the actual nature of a small bowel tumor in a large number of cases. Specific diagnosis of small bowel tumor is based on a combination of findings that are depicted owing to the use of the multiple capabilities of 64-section CT enteroclysis, allowing optimal planning prior to endoscopic or surgical resection.

Colon cancer: comprehensive evaluation with 64-section CT colonography using water enema as intraluminal contrast agent-a pictorial review.

Sixty-four-section CT colonography with water enema combines intracolonic neutral contrast agent with high-resolution CT images of the abdomen. Owing to submillimeter isotropic voxels, high-quality reformatted images are obtained. High-resolution images offer added value for the detection and localization of colonic lesions, evaluation of the local extent of the disease, and depiction, if any, of synchronous colorectal lesions and distant metastases. Sixty-four-section CT colonography with water enema has a major role in the evaluation of patients with colon cancer before planning therapy. It can be used to complement failed or incomplete colonoscopy and investigate the colon in elderly patients.

Preoperative detection of hepatic metastases: comparison of diffusion-weighted, T2-weighted fast spin echo and gadolinium-enhanced MR imaging using surgical and histopathologic findings as standard of reference.

PURPOSE: The purpose of this study was to retrospectively compare the respective sensitivities of diffusion-weighted (DW), T2-weighted fast spin-echo (T2WFSE) and gadolinium chelate-enhanced MR imaging in the preoperative detection of hepatic metastases using intraoperative ultrasonographic and histopathologic findings as the standard of reference. MATERIALS AND METHODS: Twenty-seven patients with 64 surgically and histopathologically proven hepatic metastases had MR imaging of the liver, including DW, T2WFSE and dynamic gadolinium chelate-enhanced MR imaging. Images from each MR sequence were separately analyzed by two readers with disagreements resolved by consensus readings. The findings on MR images were compared with intraoperative ultrasonographic and histopathologic findings on a lesion-by-lesion basis to determine the sensitivity of each MR sequence. Statistical review of the lesion-by-lesion analysis was performed with the McNemar test. RESULTS: DW, T2WFSE and gadolinium chelate-enhanced MR imaging allowed the depiction of 54/64 (84.4%; 95% CI: 73.1-92.2%), 44/64 (68.8%; 95% CI: 55.9-79.8%), and 51/64 (79.7%; 95% CI: 67.8-88.7%) hepatic metastases respectively. DW MR images allowed depiction of significantly more hepatic metastases than did T2WFSE and was equivalent to gadolinium chelate-enhanced MR imaging (P=.002 and P=.375, respectively). CONCLUSION: DW MR imaging is superior to T2WFSE imaging and equivalent to gadolinium chelate-enhanced MR imaging for the preoperative detection of hepatic metastases. Further studies however are needed to determine at what extent DW MR imaging can be used as an alternative to gadolinium chelate-enhanced MR imaging for the preoperative depiction of hepatic metastases.

Differentiation between cavernous hemangiomas and untreated malignant neoplasms of the liver with free-breathing diffusion-weighted MR imaging: comparison with T2-weighted fast spin-echo MR imaging.

OBJECTIVE: To test interobserver variability of ADC measurements and compare the diagnostic performances of free-breathing diffusion-weighted (FBDW) with that of T2-weighted FSE (T2WFSE) MR imaging for differentiating between cavernous hemangiomas and untreated malignant hepatic neoplasms. MATERIALS AND METHODS: Thirty-five patients with cavernous hemangiomas and 35 with untreated hepatic malignant neoplasms had FBDW and T2WFSE MR imaging. Hepatic lesions were characterized with ADC measurement and visual evaluation. Interobserver agreement for ADC measurement was calculated. Association between ADC value and lesion type was assessed using univariate analysis. Sensitivity, specificity and accuracy of ADC values and visual evaluation of MR images for the diagnosis of untreated malignant hepatic neoplasm were compared. RESULTS: ADC measurements showed excellent interobserver correlation (intraclass correlation coefficient=0.980). Malignant neoplasms had lower ADC values than hemangiomas for the two observers (1.11×10(-3) mm2/s±.21×10(-3) vs. 1.77×10(-3) mm2/s±.29×10(-3) for observer 1 and 1.11×10(-3) mm2/s±.19×10(-3) vs. 1.79×10(-3) mm2/s±.32×10(-3) for observer 2) and univariate analysis found significant correlations between lesion type and ADC values. Depending on ADC threshold value, accuracy for the diagnosis of malignant neoplasm varied from 82.9% to 94.3%. Using visual evaluation, FBDW showed better specificity and accuracy than T2WFSE MR images for the diagnosis of malignant neoplasm (97.1% vs. 77.1% and 94.3% vs. 62.9%, respectively). CONCLUSION: FBDW imaging provides reproducible quantitative information and surpasses the value of T2WFSE MR imaging for differentiating between cavernous hemangiomas and untreated malignant hepatic neoplasms.