Intravoxel incoherent motion diffusion-weighted magnetic resonance imaging for predicting histological grade of hepatocellular carcinoma: Comparison with conventional diffusion-weighted imaging.

AIM: To compare intravoxel incoherent motion (IVIM)-derived parameters with conventional diffusion-weighted imaging (DWI) parameters in predicting the histological grade of hepatocellular carcinoma (HCC) and to evaluate the correlation between the parameters and the histological grades. METHODS: A retrospective study was performed. Sixty-two patients with surgically confirmed HCCs underwent diffusion-weighted magnetic resonance imaging with twelve b values (10-1200 s/mm2). The apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) were calculated by two radiologists. The IVIM and conventional DWI parameters were compared among the different grades by using analysis of variance (ANOVA) and the Kruskal-Wallis test. Receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic efficiency of distinguishing between low-grade (grade 1, G1) and high-grade (grades 2 and 3, G2 and G3) HCC. The correlation between the parameters and the histological grades was assessed by using the Spearman correlation test. Bland-Altman analysis was used to evaluate the reproducibility of the two radiologists' measurements. RESULTS: The differences in the ADC and D values among the groups with G1, G2, and G3 histological grades of HCCs were statistically significant (P < 0.001). The D* and f values had no significant differences among the different histological grades of HCC (P > 0.05). The ROC analyses demonstrated that the D and ADC values had better diagnostic performance in differentiating the low-grade HCC from the high-grade HCC, with areas under the curve (AUCs) of 0.909 and 0.843, respectively, measured by radiologist 1 and of 0.911 and 0.852, respectively, measured by radiologist 2. The following significant correlations were obtained between the ADC, D, and D* values and the histological grades: r = -0.619 (P < 0.001), r = -0.628 (P < 0.001), and r = -0.299 (P = 0.018), respectively, as measured by radiologist 1; r = -0.622 (P < 0.001), r = -0.633 (P < 0.001), and r = -0.303 (P = 0.017), respectively, as measured by radiologist 2. The intra-class correlation coefficient (ICC) values between the two observers were 0.996 for ADC, 0.997 for D, 0.996 for D*, and 0.992 for f values, which indicated excellent inter-observer agreement in the measurements between the two observers. CONCLUSION: The IVIM-derived D and ADC values show better diagnostic performance in differentiating high-grade HCC from low-grade HCC, and there is a moderate to good correlation between the ADC and D values and the histological grades.

Human patellar cartilage: echo planar diffusion-weighted MR imaging findings at 3.0 T.

PURPOSE: To explore the findings of diffusion-weighted imaging (DWI) and the diffusion characteristics on patellar cartilage in healthy adults. MATERIALS AND METHODS: Thirty healthy subjects were studied on SIEMENS 3.0-T Trio Tim magnetic resonance (MR) scanner. The apparent diffusion coefficient (ADC) values of the patellar cartilage were measured in different areas. RESULTS: The patellar cartilage demonstrated homogeneously high signal intensity on the images of DWI and maps of ADC. The ADC values displayed a spatial dependency, approximately (1.17 ± 0.31)×10(-3) mm(2)/s of the entire cartilage. CONCLUSIONS: Diffusion-weighted MR imaging may display articular cartilage structure. There is a consistent pattern of spatial variation of the ADC values.

Non-enhanced MR angiography of renal artery using inflow-sensitive inversion recovery pulse sequence: a prospective comparison with enhanced CT angiography.

PURPOSE: To prospectively evaluate the diagnostic value of non-enhanced inflow-sensitive inversion recovery (IFIR) MR angiography for the detection of renal artery stenosis (RAS), with enhanced CT angiography performed as the reference standard. MATERIALS AND METHODS: Sixty consecutive patients suspected of RAS underwent both of IFIR MR and enhanced CT angiography. Subjective image quality, renal artery depiction and renal artery grading were all evaluated on artery-by-artery basis. Spearman rank correlation analysis was used to assess agreement between the two techniques. The diagnostic sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for RAS detection at IFIR MR angiography were calculated. RESULTS: One hundred twenty-six main renal arteries were visualized on enhanced CT and non-enhanced MR angiographic images, respectively. The Spearman rank correlation was 0.773 (P<.001) for renal artery depiction, 0.998 (P<.001) for renal arteries grading and 0.833 (P<.001) for RAS detection between the two modalities. The sensitivity, specificity, PPV and NPV of IFIR MR angiography for RAS detection demonstrated 100%, 99.0%, 92.0% and 100%, respectively. CONCLUSION: Non-enhanced IFIR MR angiography had high sensitivity, specificity, PPV and NPV for RAS detection. It could be the first choice of renal artery imaging methods to avoid ionizing irradiation and renal toxicity from contrast media.

Epiphyseal and physeal injury: comparison of conventional radiography and magnetic resonance imaging.

PURPOSE: To compare conventional radiography and magnetic resonance imaging (MRI) in the assessment of epiphyseal and physeal injury. MATERIALS AND METHODS: Seventeen cases with epiphyseal and physeal injury were examined with conventional radiography and MRI. Two blinded experienced radiologists separately evaluated the results retrospectively. RESULTS: Two Salter-Harris II fractures showed displacement of epiphysis and metaphyseal fragment, as well as T1 hypointensity and T2 hyperintensity in the physis on MRI. Three Salter-Harris IV fractures showed a fracture line in the epiphysis and metaphysis on two modalities, as well as linear T2 hyperintensity in the physis. All five slipped epiphysis showed signal intensity abnormality in the physis on MRI aside from the physeal widening and epiphyseal displacement seen on radiographs. Seven patients with bony bridge formation showed premature closure of the physis, shortening, and remodeling of the end of bones involved. CONCLUSIONS: Conventional radiography and MRI are both useful in the diagnosis of epiphyseal and physeal injury. MRI can provide more detailed information, which could direct treatment planning and prognosis predicting.