18 F-FDG PET/MRI of Primary Hepatic Malignancies: Differential Diagnosis and Histologic Grading

BACKGROUND: Distinguishing between IHCC and HCC is important because of their differences in treatment and prognosis. The hybrid Positron Emission Tomography/magnetic Resonance Imaging (PET/MRI) system has become more widely accessible, with oncological imaging becoming one of its most promising applications. OBJECTIVE: The objective of this study was to see how well 18F-fluorodeoxyglucose (18F-FDG) PET/MRI could be used for differential diagnosis and histologic grading of primary hepatic malignancies. METHODS: We retrospectively evaluated 64 patients (53 patients with HCC, 11 patients with IHCC) with histologically proven primary hepatic malignancies using 18F-FDG/MRI. The Apparent Diffusion Coefficient (ADC), Coefficient of Variance (CV) of the ADC, and standardized uptake value (SUV) were calculated. RESULTS: The mean SUVmax value was higher for IHCC (7.7 ± 3.4) than for HCC (5.2 ± 3.1) (p = 0.019). The area under the curve (AUC) was 0.737, an optimal 6.98 cut-off value providing 72% sensitivity and 79% specificity. The ADCcv value in IHCC was statistically significantly higher than in HCC (p=0.014). ADC mean values in HCCs were significantly higher in low-grade tumors than in high-grade tumors. The AUC value was 0.73, and the optimal cut-off point was 1.20x10-6 mm2/s, giving 62% sensitivity and 72% specificity. The SUVmax value was also found to be statistically significantly higher in the high-grade group. The ADCcv value in the HCC low-grade group was found to be lower than in the highgrade group (p=0.036). CONCLUSION: 18F FDG PET/MRI is a novel imaging technique that can aid in the differentiation of primary hepatic neoplasms as well as tumor-grade estimation.

The comparison of pancreatic and hepatic steatosis in healthy liver donor candidates.

The aim of this study was to investigate the relationship between nonalcoholic fatty liver disease (NAFLD) and pancreatic steatosis (PS) in patients with biopsy-proven NAFLD. 228 patients with biopsy-proven NAFLD patients who admitted to the Faculty of Medicine of Demiroglu Bilim University between 2004 and 2019 were included in the study. Demographic, laboratory, histological and radiological findings of the patients were recorded retrospectively. Hepatosteatosis (HS) levels were measured by both CT and biopsy, while PS levels were measured by 3 different CT-based techniques. 89 (39%) of the patients were female and 139 (61%) were male. The mean body mass index (BMI) was 27.2 ± 4.0. Biochemical parameters were within normal limits. Liver biopsy showed a significant correlation with HS grade on CT scan (p < 0.001). When CT findings were compared, a significant correlation was found between PS and HS (p < 0.05), but there was no correlation between the HS level in biopsy and the pancreatic adiposity on CT (p > 0.05). Our study was the first to compare biopsy-proven NAFLD and PS, and no correlation was found between biopsy-proven NAFLD and PS.

Intravoxel Incoherent Motion of Colon Cancer Liver Metastases for the Assessment of Response to Antiangiogenic Treatment: Results from a Pilot Study.

OBJECTIVE: This study was aimed at evaluating the intravoxel incoherent motion (IVIM) parameter alterations of liver metastases of colorectal carcinoma (CRC) during antiangiogenic bevacizumab combination therapy. METHODS: Twenty-five patients with CRC liver metastases treated with bevacizumab in combination with FOLFOX-or-FOLFIRI protocols were enrolled in the study. MRI was performed using a 1.5-tesla scanner pre-treatment (PT) and at 3, 6, and 9 months of therapy. Routine abdominal MRI sequences and an IVIM-DWI (diffusion-weighted imaging) sequence were obtained. The IVIM-DWI sequence was executed with 16 b-values varying from 0 to 1,400 s/mm2. The mean values of apparent diffusion coefficient (ADC), true diffusion (D), pseudodiffusion (D*), and perfusion fraction (f) of each metastasis were obtained for all b-values, and the time-related changes were recorded to analyze the chronologic responses to antiangiogenic therapy. The RECIST 1.1 criteria were used for the evaluation of treatment response. RESULTS: The diameters of the metastases diminished significantly at 9 months when compared with PT (p = 0.03). The D (p = 0.10) and ADC (p = 0.21) values of the metastases increased at 9 months of therapy. D* was the highest at 3 months (p =0.24); it decreased at 6 (p =0.97) and 9 months (p =0.87) of therapy. The f value had peaked at 3 months (p =0.51) and started to decrease thereafter. At 6 months, f decreased to the lowest values (p =0.12). CONCLUSION: IVIM parameters, particularly the perfusion fraction, may quantitatively reflect the response to antiangiogenic treatment. The antiangiogenic response manifests after 3 months of therapy before the RECIST-related response.

Intravoxel Incoherent Motion Parameters for Assessing the Efficiency of Locoregional Bridging Treatments before Liver Transplantation.

OBJECTIVE: To evaluate the diagnostic accuracy of Intravoxel Incoherent Motion (IVIM) parameters for assessment of tumor response after locoregional treatment (LRT) of hepatocellular carcinoma (HCC). METHODS: Fifteen patients with HCC who had undergone LRTs (11 transarterial radioembolization, 4 transarterial chemoembolization) were included. In addition to routine upper abdominal magnetic resonance imaging sequences, IVIM with 16 different b values and conventional diffusion weighted imaging with 3 different b factors were obtained immediately before and 8 weeks after LRTs. Magnetic resonance imaging response was evaluated according to modified Response Evaluation Criteria in Solid Tumors (mRECIST) and HCCs were categorized into 2 subgroups, responders and nonresponders. Quantitatively, the number of diffusion-changes were calculated with apparent diffusion coefficient (ADC) and IVIM parameters, including mean D (true diffusion coefficient), pseudo-diffusion coefficient associated with blood flow, and f (perfusion fraction) values. Subsequently, the pre- and post-treatment parameters were compared using the Mann-Whitney U test. RESULTS: Considering all HCCs, a significant decrease was observed according to mRECIST criteria (-38.43 ± 16.49). The ADC and D values after LRTs were significantly higher than those of the preceding ones. The f values after LRTs were significantly lower than those of pre-treatment. In the responders group, ADC and D values were significantly increased and f values were significantly decreased after LRTs. No difference of statistical significance was achieved in the nonresponders group. CONCLUSIONS: ADC values and IVIM parameters appear to reflect the response of LRTs as effectively as those of mRECIST. This promises new horizons in the management of pretransplant patients, especially in renal insufficiency clinical settings, owing to the elimination of contrast media administration.

Value of Intravoxel Incoherent Motion for Hepatocellular Carcinoma Grading.

BACKGROUND: To evaluate the diagnostic accuracy of intravoxel incoherent motion (IVIM) parameters in estimation of hepatocellular carcinoma (HCC) grading. MATERIALS AND METHODS: Twenty-nine patients with histopathologically diagnosed as 42 HCC at explant were included in this retrospective study. All patients were examined by 1.5T magnetic resonance imaging with the use of 4-channel phased array body coil. In addition to routine pre- and postcontrast sequences, IVIM (16 different b factors varying from 0 to 1300 s/mm2) and conventional diffusion-weighted imaging (3 different b factors of 50, 400, 800 s/mm2) were obtained with single-shot echo planar spin echo sequence. Apparent diffusion coefficient (ADC) and IVIM parameters including mean D (true diffusion coefficient), D* (pseudo-diffusion coefficient associated with blood flow), and f (perfusion fraction) values were calculated. Histopathologically, HCC was classified as low (grade 1, 2) and high (grade 3, 4) grade in accordance with the Edmondson-Steiner score. Quantitatively, ADC, D, D*, and f values were compared between the low- and high-grade groups by Student t test. The relationship between the parameters and histologic grade was analyzed using the Spearman's correlation test. To evaluate the diagnostic performance of the parameters, receiver operating characteristic analysis was performed. RESULTS: High-grade HCCs had significantly lower ADC and D values than low grade groups (P = .005 and P = .026, retrospectively); ADC and D values were inversely correlated with tumor grade (r = -0.519, P = .011, r = -0.510, P = .026, respectively). High-grade HCCs had significantly higher f values when compared with the low-grade group (P = .005). The f values were positively correlated with tumor grade (r = 0.548, P = .007). The best discriminative parameter was f value. Cut-off value of 32% of f values showed sensitivity of 75.6% and a specificity of 73.5%. CONCLUSION: ADC values and IVIM parameters such as f values appear to reflect the grade of HCCs.

Novel Application of Internal-External Drainage Catheter as Biliary Stent for Percutaneous Transhepatic Treatment of Biliary Strictures in Living Donor Liver Transplantation Recipient Patients.

OBJECTIVES: Although endoscopic management is considered as the first-line treatment for biliary strictures, it may be challenging in living donor liver transplant recipients due to the complex nature of duct-to-duct reconstruction. In this study we present the use of a pigtail drainage catheter as a biliary stent to treat biliary strictures after a living donor liver transplant. METHODS: Twenty-seven patients with biliary strictures were treated with our novel technique. In this technique, a pigtail catheter was trimmed into 3 parts (proximal, middle, and distal portions). A suture string was passed through the distal hole of the middle portion, which was then reversed and used as a stent while the proximal portion was used as a pusher. Following balloon dilation of the stenotic segment, the distal, reversed middle, and proximal portions were loaded over the guidewire. After proper placement of the stent, the retractor suture string, pusher, and guidewire were removed. The stent was removed during the third or fourth month of placement through endoscopic retrograde cholangiopancreatography (ERCP) in all patients. RESULTS: No significant complications developed during the procedure or follow-up period. Ten patients required re-stenting by ERCP during the same session. The mean follow-up period was 2 years. Cholestase enzymes and bilirubin levels were within normal limits in all patients during follow-up. CONCLUSION: Stents derived from drainage catheter facilitate treatment of biliary strictures in patients not eligible for the retrograde approach. This stent is cheap, easy to implement, can be easily removed by ERCP, and re-stenting can be applicable in retrograde if needed.

Value of Imaging Findings in the Prediction of Microvascular Invasion in Hepatocellular Carcinoma.

BACKGROUND: The purpose of this study was to determine the utility of some imaging findings in predicting microvascular invasion (MVI) and hepatocellular carcinoma (HCC) recurrence risk after liver transplantation. METHOD: This retrospective study included 123 patients with histopathologically proven HCC at explant. All HCCs were classified as MVI positive (group I) or negative (group II) based on histopathological findings. In each group, multifocality, largest tumor size, bulging (tumor causing liver capsule expansion), beak sign (the acute angle between the tumor and liver parenchyma), and diffusion restriction on diffusion weighted images (DWI) were evaluated. These findings were compared between the groups by Student's t test. The relation between the parameters and MVI was analyzed by using the Spearman's correlation test. RESULTS: Of the total patients, 30.1% had MVI (group I) and 69.9% (group II) did not have MVI. Presence of beak sign (P ≤ .005), bulging sign (P = .002), and diffusion restriction (P = .045) were significantly more frequent in group I than group II. The beak sign, bulging sign, and diffusion restriction were correlated with presence of MVI. Largest tumor size and multifocality were higher in group I than group II, but the differences were not statistically significant. CONCLUSION: Radiologists and transplant surgeons should be aware of some clue imaging findings, especially beak and bulging signs because these findings may predict the presence of MVI in HCC. These patients might benefit from histologic confirmation of the tumor characteristics through biopsy and subsequent bridging treatment options before liver transplantation to reduce the risk of recurrence.

The Performance of Radiographic Criteria for Bone Malignancy When Applied to Computed Tomography and Magnetic Resonance Imaging.

BACKGROUND: The conventional radiologic features that differentiate benign from malignant bone lesions were originally described using radiography (x-ray [XR]). When evaluating sectional imaging studies such as magnetic resonance imaging (MRI) and computed tomography (CT), one may apply these principles to identify malignant bone lesions. The aim of this study was to evaluate the performances of these radiographic features for detecting malignity when applied to CT and MRI. MATERIALS AND METHODS: This retrospective study was approved by our institutional ethical board. Thirty-nine patients with histopathologic proof of a high-grade bone malignancy and preoperative imaging data obtained with a minimum of two different modalities were included in the study. Four radiologists reviewed the images and scored the lesions for distinctness of margins, presence and type of periosteal reaction, matrix mineralization, and presence of soft tissue mass. The average score for each modality was then tested for accuracy with regard to the histopathology. RESULTS: When lesion margins were considered, XR was the best modality to detect a high-grade malignancy. MRI, especially postcontrast T1-weighted sequence, was the least helpful in this regard. There was no significant difference between CT and XR and between CT and MRI. When the periosteal reaction was considered, XR was the best modality to detect the malignant type of periosteal reaction. In this regard, MRI and CT were misleading; either by not detecting or undergrading periosteal reaction. MRI was the best modality to detect soft tissue mass. CONCLUSION: Conventional imaging criteria for bone malignancy can be misleading when applied to MRI or CT. When cross-sectional imaging features contradict those from XR, the latter should be the guide for clinical management.

Diagnostic Accuracy of Dynamic Contrast Enhanced Magnetic Resonance Imaging in Characterizing Lung Masses.

BACKGROUND: Imaging plays a critical role not only in the detection, but also in the characterization of lung masses as benign or malignant. OBJECTIVES: To determine the diagnostic accuracy of dynamic magnetic resonance imaging (MRI) in the differential diagnosis of benign and malignant lung masses. PATIENTS AND METHODS: Ninety-four masses were included in this prospective study. Five dynamic series of T1-weighted spoiled gradient echo (FFE) images were obtained, followed by a T1-weighted FFE sequence in the late phase (5th minutes). Contrast enhancement patterns in the early (25th second) and late (5th minute) phase images were evaluated. For the quantitative evaluation, signal intensity (SI)-time curves were obtained and the maximum relative enhancement, wash-in rate, and time-to-peak enhancement of masses in both groups were calculated. RESULTS: The early phase contrast enhancement patterns were homogeneous in 78.2% of the benign masses, while heterogeneous in 74.4% of the malignant tumors. On the late phase images, 70.8% of the benign masses showed homogeneous enhancement, while most of the malignant masses showed heterogeneous enhancement (82.4%). During the first pass, the maximum relative enhancement and wash-in rate values of malignant masses were significantly higher than those of the benign masses (P = 0.03 and 0.04, respectively). The cutoff value at 15% yielded a sensitivity of 85.4%, specificity of 61.2%, and positive predictive value of 68.7% for the maximum relative enhancement. CONCLUSION: Contrast enhancement patterns and SI-time curve analysis of MRI are helpful in the differential diagnosis of benign and malignant lung masses.

High-resolution computed tomography and rheumatoid arthritis: semi-quantitative evaluation of lung damage and its correlation with clinical and functional abnormalities.

BACKGROUND: We aimed to establish risk factors for radiological lung damage associated with rheumatoid arthritis (RA) and determine whether clinical findings and pulmonary function test were correlated with Warrick score calculated on the basis of high-resolution computed tomography or not. METHODS: One hundred thirty RA patients who were followed at rheumatology outpatient clinic were included through retrospective screening. To evaluate radiological involvement, the semi-quantitative evaluation proposed by Warrick was used to assign a score for each lesion based on the severity and extent of the pulmonary damage. In addition to the total score, indices for alveolitis and fibrosis were created. The correlations between each score and clinical and functional parameters were tested for all patients. RESULTS: We showed that age was an independent explanatory variable of radiological lung damage. Percentage of predicted lung diffusion capacity for carbon monoxide (DLco) below 75 % and presence of respiratory symptoms were found to contribute more to radiological lung damage. Warrick score was positively correlated with age at study onset (r = 0.43, p < 0.001). In addition, a negative correlation was found between Warrick score and DLco % predicted (r = -0.357, p = 0.001). Alveolitis index was negatively correlated with DLco % predicted (r = -0.321, p = 0.003). CONCLUSIONS: It is considered that this semi-quantitative method may have added value in early diagnosis, appropriate treatment decisions and follow-up when taken into account together with risk factors associated with pulmonary damage in RA.

Diffusion-weighted Magnetic Resonance Imaging in the Differential Diagnosis of Benign and Metastatic Malignant Pleural Thickening.

PURPOSE: Imaging plays a critical role not only in detection but also in characterization of pleural thickening as benign or malignant. The aim of the study was to investigate the value of diffusion-weighted (DW) imaging in the differential diagnosis of benign and metastatic malignant pleural thickening. MATERIALS AND METHODS: Thirty-four patients with 64 pleural foci of nodular thickening (47 metastatic malignant and 17 benign) were included in this prospective study. DW imaging was performed using a breath-hold single-shot spin-echo echo-planar sequence. Two different apparent diffusion coefficient (ADC1,2) maps were obtained with different b factors (ADC1 reconstructed from b factors of 0 and 650 mm/s and ADC2 reconstructed from b factors of 0 and 1000 mm/s), and ADCs were calculated. Quantitatively, ADCs were compared between the groups, and the optimal cutoff value was found by using receiver operating characteristic curve analysis. RESULTS: Quantitatively, differences in signal intensities on DW trace images with b factors of 650 and 1000 mm/s were not statistically significant. The ADC1 and ADC2 of the metastatic malignant thickening were significantly lower than those of benign ones [mean ADC1 was 1.37±0.65×10 mm/s for metastatic malignant thickening and 2.11±0.69×10 mm/s for benign thickening (P=0.045); ADC2 was 1.06±0.56×10 mm/s for metastatic malignant thickening and 1.56±0.71×10 mm/s for benign thickening (P=0.038)]. However, because of the ADC overlap between malignant and benign disease, a sufficiently discriminative cutoff value could not be defined by the receiver operating characteristic curve analysis. CONCLUSION: Despite fair sensitivity and specificity, DW imaging may serve as a complementary tool that improves the differential diagnosis of pleural thickening.

Major depressive disorder in chronic heart failure patients: Does silent cerebral infarction cause major depressive disorder in this patient population?

OBJECTIVE: Depression frequently occurs in patients with heart failure as similar pathophysiological mechanisms present in both these diseases. Patients with dilated cardiomyopathy (DCM) have a high incidence of clinically asymptomatic silent cerebral infarction (SCI). This study aimed to evaluate the relation between SCI and major depressive disorder (MDD), and between MDD and clinical and biochemical parameters in DCM patients. METHODS: Patients with ischemic and non-ischemic DCM who had chronic heart failure (CHF) (39 male, 10 female, age 60±10 years) were included in the study. Mean patient ejection fraction (EF) was 34±10%. Patients had no localized neurological symptoms or stroke history. The etiology of DCM was ischemic in 40 and non-ischemic in 9 patients. Twenty-five age-matched healthy volunteers served as a control group for comparison of SCI and MDD prevalence. RESULTS: Patients had mild to severe CHF symptoms. Prevalence of SCI and MDD was significantly higher in patients with DCM than in the control group; 63% vs 8%; p<0.001, and 52% vs 20%; p<0.001 respectively. Patients with SCI had a higher prevalence of MDD than patients without SCI in DCM (61% vs 27%, p=0.02). CONCLUSION: CHF patients have an increased prevalence of SCI and MDD. Patients with SCI have a higher prevalence of MDD compared to patients without SCI in CHF.

Comparison of the diagnostic performances of diffusion parameters in diffusion weighted imaging and diffusion tensor imaging of breast lesions.

PURPOSE: To evaluate the diagnostic efficiency of the diffusion parameters measured by conventional diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for discrimination of malignant breast lesions from benign lesions and the normal breast. MATERIALS AND METHODS: The study included 52 women with 55 breast lesions (30 malignant, 25 benign). DTI and DWI were performed complementary to dynamic contrast MRI at 3T. Apparent diffusion coefficient (ADC) of DWI, mean diffusivity (MD) and fractional anisotropy (FA) values of DTI were measured for lesions and contralateral breast parenchyma in each patient. We used b factors of 0, 50, 850, 1000 and 1500 s/mm(2) for DWI and b 0 and 1000 s/mm(2) for DTI. ADC, MD and FA values were compared between malignant and benign lesions, and the normal parenchyma by univariate and multivariate analyses. RESULTS: Diffusion parameters showed no difference according to menopausal status in the normal breast. ADC and MD values of the malignant lesions were significantly lower than benign lesions and normal parenchyma (p=0.001). The FA showed no statistical significance. With the cut-off values of ≤ 1.23 × 10(-3)mm(2)/s (b 0-1000 s/mm(2)) and ≤ 1.12 × 10(-3)mm(2)/s (b 0-1500 s/mm(2)), ADC showed 92.85% and 96.15% sensitivity; 72.22% and 73.52% PPV, respectively. With a cut-off value of ≤ 1.27 × 10(-3)mm(2)/s (b 1000 s/mm(2)), MD was 100% sensitive with a PPV of 65.90%. Comparing the diagnostic performance of the parameters in DTI with DWI, we obtained similar efficiency of ADC with b values of 0,1000 and 0,1500 s/mm(2) and MD with a b value of 0, 1000 s/mm(2) (AUC = 0.82 ± 0.07). CONCLUSION: ADC of DWI and MD of DTI values provide significant discriminative factors for benign and malignant breast lesions. FA measurement was not discriminative. Supported with clinical and dynamic contrast MRI findings, DWI and DTI findings provide significant contribution to the final radiologic decision.

Characterization of malignant thrombus in an invasive thymoma with intravascular growth.

We report an unusual case of an invasive thymoma with a thrombus in the right atrium and describe the radiological findings consistent with the malignant nature of the thrombus. The thrombus showed significant enhancement on computerized tomography images similar to the tumoral mass. On magnetic resonance imaging, both the tumor and the thrombus have heterogeneously high signal intensities on T2-weighted images. On diffusion-weighted images they both exhibit high signal intensity and low apparent diffusion coefficient (ADC) values which support the malignant nature of the thrombus and the mass.

Preoperative evaluation of myometrial invasion in endometrial carcinoma: diagnostic performance of 3T MRI.

PURPOSE: To evaluate the diagnostic accuracy of 3T MRI in preoperative staging of myometrial invasion. METHODS: Twenty-eight women with histological diagnosis of endometrial carcinoma were included in this prospective study. After T2-W SS-TSE and DWI, dynamic series of T1-W THRIVE images were obtained (0-180 s) followed by a T1-W THRIVE sequence in the late phase (5th min). For detection of deep myometrial infiltration: sensitivity, specificity, PPV, NPV, and accuracy were calculated on T2-W, postcontrast early arterial and late phase T1-W, and DWI. For the quantitative analysis of DWI, ADC values of the tumor were calculated and correlated with histologic grade. For the quantitative evaluation of dynamic series, SI-time curves were obtained and the maximum relative enhancement, wash-in rate, time-to-peak, and wash-out rate of masses and myometrium were compared. RESULTS: T2-W and early phase contrast-enhanced sequences obtained sensitivity 100 %, specificity 76 %, PPV 58 %, NPV 100 %, and accuracy 82 %; late-phase contrast-enhanced images obtained sensitivity 100 %, specificity 81 %, PPV 64 %, NPV 100 %, and accuracy 86 %; DWI obtained lower accuracy [sensitivity 71 %, specificity 62 %, PPV 38 %, NPV 87 %, and accuary 57 %] than T2-W and postcontrast images. The MRE of carcinomas were significantly lower than those of the myometrium. This analysis showed a significant improvement in tumor versus myometrium contrast during the late phase. On DWI, the mean ADC value of tumor was 1.02 ± 0.48 × 10(-3). There was no statistically significant correlation between tumor grades and ADCs. CONCLUSIONS: As the 3T MRI scanner allows high-resolution images, accurate assessment of myometrial infiltration can be done especially with postcontrast late phase images.

Diagnostic performance of conventional diffusion weighted imaging and diffusion tensor imaging for the liver fibrosis and inflammation.

OBJECTIVE: To evaluate the diagnostic accuracy of liver apparent diffusion coefficient (ADC) measured with conventional diffusion-weighted imaging (CDI) and diffusion tensor imaging (DTI) for the diagnosis of liver fibrosis and inflammation. MATERIALS AND METHODS: Thirty-seven patients with histologic diagnosis of chronic viral hepatitis and 34 healthy volunteers were included in this prospective study. All patients and healthy volunteers were examined by 3T MRI. CDI and DTI were performed using a breath-hold single-shot echo-planar spin echo sequence with b factors of 0 and 1000 s/mm(2). ADCs were obtained with CDI and DTI. Histopathologically, fibrosis of the liver parenchyma was classified with the use of a 5-point scale (0-4) and inflammation was classified with use of a 4-point scale (0-3) in accordance with the METAVIR score. Quantitatively, signal intensity and the ADCs of the liver parenchyma were compared between patients stratified by fibrosis stage and inflammation grade. RESULTS: With a b factor of 1000 s/mm(2), the signal intensity of the cirrhotic livers was significantly higher than those of the normal volunteers. In addition, ADCs reconstructed from CDI and DTI of the patients were significantly lower than those of the normal volunteers. Liver ADC values inversely correlated with fibrosis and inflammation but there was only statistically significant for inflammatory grading. CDI performed better than DTI for the diagnosis of fibrosis and inflammation. CONCLUSION: ADC values measured with CDI and DTI may help in the detection of liver fibrosis. They may also give contributory to the inflammatory grading, particularly in distinguishing high from low grade.

Anterior visual pathways in amblyopia: quantitative assessment with diffusion tensor imaging.

PURPOSE: To detect the abnormalities of the anterior visual pathways in children with amblyopia with diffusion tensor imaging. METHODS: Ten children with unilateral amblyopia, 5 children with bilateral amblyopia, and 10 control children were treated using diffusion tensor imaging scanning in this institutional practice. Fractional anisotropy and mean diffusivity values were analyzed using diffusion tensor imaging in the prechiasmatic and chiasmatic regions. Fractional anisotropy and mean diffusivity values of the amblyopic groups were compared with the values of the control group using the Kruskal­Wallis test. The Mann­Whitney U test was used to evaluate pairwise differences between groups. RESULTS: When compared with the control group, prechiasmatic fractional anisotropy values were significantly decreased in both affected and sound fellow eyes in the unilateral amblyopic group (P = .019 and .013), but not in the bilateral amblyopic group (P = .221). Mean diffusivity values were significantly greater in the sound fellow eye in the unilateral amblyopic group in the prechiasmatic region (P = .001 and .049). CONCLUSION: Diffusion tensor imaging showed a significant decrease in fractional anisotropy and an increase in mean diffusivity values in the unilateral amblyopic group in both affected and sound fellow eyes. These findings may reflect axonal underdevelopment in anterior pathways, particularly in the unilateral amblyopic group.

Differentiation of malignant and benign lung lesions with diffusion-weighted MR imaging.

BACKGROUND: The aim of the study was to evaluate the role of diffusion-weighted magnetic resonance imaging in the differential diagnosis of lung lesions. PATIENTS AND METHODS.: Sixty-seven patients with lung lesions (48 malignant, 19 benign) were included in this prospective study. Signal intensities (SIs) were measured in diffusion-weighted MR images that were obtained with b=0, 500 and 1000 s/mm(2) values. Apparent diffusion coefficient (ADC) maps were calculated by using images with b=0 and 1000 s/mm(2) values. The statistical significance was determined using the Student-t test. RESULTS: The SIs of malignant lesions were significantly higher than those of benign lesions (p<0.004 for b=0 s/mm(2) and p<0.000 for the other b values). Using b=500 s/mm(2), SI≥391 indicated a malignant lesion with a sensitivity of 95%, specificity of 73% and positive predictive value of 87%. Using b=1000 s/mm(2), SI≥277 indicated a malignant lesion with a sensitivity of 93%, specificity of 69% and positive predictive value of 85%. There was no significant difference between malignant and benign lesions regarding ADC values (p=0.675). There was no significant difference in SIs or ADC values between small cell carcinoma and non-small cell carcinoma. When comparing undifferentiated with well- partially differentiated cancers, SIs were higher with all b values, but the difference was statistically significant only with b=1000 s/mm(2) (p<0.04). CONCLUSIONS: Diffusion-weighteted MR trace image SI is useful for the differentiation of malignant versus benign lung lesions.

Malignant versus benign mediastinal lesions: quantitative assessment with diffusion weighted MR imaging.

OBJECTIVES: We aimed to evaluate the performance of diffusion-weighted magnetic resonance imaging in differentiating malignant from benign mediastinal lesions. METHODS: Fifty-three mediastinal lesions were examined with T1- and T2-weighted (W) conventional images. Then, two diffusion-weighted images were obtained with b = 0 and 1000 s/mm² values and apparent diffusion coefficients (ADC) were calculated. The statistical significance of differences between measurements was tested using the Student-t test. RESULTS: The mean ADC of malignant lesions was significantly lower than that of the benign masses (p < 0.001). The cut-off value of ≤ 1.39 × 10(-3) mm²/s indicated a malignant lesion with a sensitivity of 95% and specificity of 87%. CONCLUSION: Diffusion-weighted imaging may be helpful in differentiating benign from malignant mediastinal masses.