What is the most suitable MR signal index for quantitative evaluation of placental function using Half-Fourier acquisition single-shot turbo spin-echo compared with T2-relaxation time?

Background Half-Fourier acquisition single-shot turbo spin-echo (HASTE) imaging is now widely used for placental and fetal imaging because of its rapidity and low sensitivity to fetal movement. If placental dysfunction is also predicted by quantitative value obtained from HASTE image, then it might be beneficial for evaluating placental wellbeing. Purpose To ascertain the most suitable magnetic resonance (MR) signal indexes reflecting placental function using HASTE imaging. Material and Methods This retrospective study included 37 consequent patients who had given informed consent to MR imaging (MRI) examinations. All had undergone MRI examinations between February 2014 and June 2015. First, the correlation between T2-relaxation time of normal placenta and gestational age (GA) was examined. Second, correlation between signal intensity ratios (SIRs) using HASTE imaging and placental T2-relaxation time were assessed. The SIRs were calculated using placental signal intensity (SI) relative to the SI of the amniotic fluid, fetal ocular globes, gastric fluid, bladder, maternal psoas major muscles, and abdominal subcutaneous adipose tissue. Results Among the 37 patients, the correlation between T2-relaxation time of the 25 normal placentas and GA showed a moderately strong correlation (Spearman rho = -0.447, P = 0.0250). The most significant correlation with placental T2-relaxation time was observed with the placental SIR relative to the maternal psoas major muscles (SIRpl./psoas muscle) (Spearman rho = -0.531, P = 0.0007). Conclusion This study revealed that SIRpl./psoas muscle showed the best correlation to placental T2-relaxation time. Results show that SIRpl./psoas muscle might be optimal as a clinically available quantitative index of placental function.

Differentiation of Seromucinous Borderline Tumor from Serous Borderline Tumor on MR Imaging.

PURPOSE: Seromucinous borderline tumor (SMBT) is a newly categorized ovarian tumor in the 2014 revised World Health Organization (WHO) classification. SMBT is similar to serous borderline tumor (SBT) on MRI reflecting their pathological findings. This study was conducted to demonstrate the usefulness of MRI findings and quantitative values for differentiating SMBT from SBT. METHODS: This retrospective study examined 23 lesions (20 patients) from SMBT and 26 lesions (22 patients) from SBT. The following quantitative values were evaluated using receiver-operating characteristics analysis: overall and solid portion sizes, intracystic fluid signal intensity (SI) ratio compared with skeletal muscle on T1weighted image (T1WI) and T2weighted image (T2WI), contrast enhancement (CE) ratio, and mean and minimum apparent diffusion coefficient values of the solid portion. Two radiologists evaluated the prevalence of MRI finding characteristics of SMBT and SBT. The SI of the intracystic fluid on T1WI and T2WI and the association with endometriosis were evaluated visually. RESULTS: The CE ratio was significantly higher in SBT (P = 0.007). It achieved the highest area under the curve (AUC) (0.739). The fluid SI ratio on T1WI was higher in SMBT (P = 0.036, AUC = 0.676). Exophytic growth of the solid portion was observed only in SBT (P = 0.011). Intracystic fluid SI of SMBT was higher on T1WI and lower on T2WI in visual evaluation (P = 0.008 and 0.007, respectively). Findings suggesting endometriosis were observed more frequently in SMBT patients (P = 0.019). CONCLUSION: Higher CE ratio of the solid portion and exophytic growth were findings suggesting SBT. Higher intracystic fluid SI on T1WI and lower SI on T2WI suggested SMBT. MRI findings suggesting endometriosis favored the diagnosis of SMBT.

Diagnostic performance of MR imaging findings and quantitative values in the differentiation of seromucinous borderline tumour from endometriosis-related malignant ovarian tumour.

OBJECTIVES: To evaluate the diagnostic performance of quantitative values and MRI findings for differentiating seromucinous borderline tumours (SMBTs) from endometriosis-related malignant ovarian tumours (MT). METHODS: This retrospective study examined 19 lesions from SMBT and 84 lesions from MT. The following quantitative values were evaluated using receiver-operating characteristic analysis: overall and solid portion sizes, fluid signal intensity (SI), degree of contrast-enhancement, and mean and minimum apparent diffusion coefficient (ADC) values of the solid portion. Two radiologists independently evaluated four MRI findings characteristic of SMBT, fluid SI on the T1-weighted image and SI of the solid portion on diffusion-weighted image. The diagnostic values of these findings and interobserver agreement were assessed. RESULTS: For diagnosing SMBT, the mean ADC value of the solid portion showed the greatest area under the curve (0.860) (cut-off value: 1.31 × 10-3 mm2/s, sensitivity: 1.00, specificity: 0.61). The T2-weighted image (T2WI) high SI solid portion was the most useful finding, with high specificity and interobserver agreement (sensitivity, 0.58; specificity, 0.95-0.96, kappa = 0.96), followed by T2WI low SI core (sensitivity, 0.48-0.63; specificity, 0.98, kappa = 0.68). CONCLUSION: Mean ADC values of the solid portion, T2WI high SI solid portion, and T2WI low SI core were useful for differentiating SMBT from MT. KEY POINTS: • SMBT is a newly categorised ovarian tumour often associated with endometriosis. • Differentiation of SMBT from endometriosis-related malignant ovarian tumour is clinically important. • Diagnostic performances of quantitative values and MRI findings were evaluated. • Mean ADC value of the solid portion was the most useful value. • "T2WI high SI solid portion" was the most useful MRI finding.