Malignant hepatic tumor detection with ferumoxide-enhanced magnetic resonance imaging: Is chemical-shift-selective fat suppression necessary for fast spin-echo sequence?

Percentage of signal intensity loss for characterisation of focal liver lesions in patients with chronic liver disease using ferucarbotran-enhanced MRI

The purpose of this study was to determine the percentage of signal intensity loss (PSIL) threshold for the characterisation of focal liver lesions among patients with chronic liver disease. 55 nodules in 49 patients with chronic liver disease who underwent ferucarbotran-enhanced MR studies were included. Among the 49 patients, 40 had liver cirrhosis and 9 had chronic hepatitis. 8 haemangiomas, 3 focal nodular hyperplasia, 9 dysplastic nodules and 12 well, 19 moderately and 4 poorly differentiated hepatocellular carcinomas (HCCs) were revealed. The PSIL, signal-to-noise ratio and contrast-to-noise ratio of each lesion type were calculated. The diagnostic performance of PSIL on ferucarbotran-enhanced T(2) weighted images (PSIL(T2WI)) and T(2) weighted fat-suppression images (PSIL(FS-T2WI)) that characterised hepatic tumours was compared with receiver operating characteristic (ROC) analysis. Using ROC analysis, the diagnostic performance of PSIL(FS-T2WI) was superior to that of PSIL(T2WI) (p = 0.01). The mean PSIL(FS-T2WI) of the benign lesions was significantly higher than that of HCC (p<0.001), and the mean PSIL(FS-T2WI) of well-differentiated HCC was significantly higher than that of moderately/poorly differentiated HCCs (p = 0.001). With a PSIL(FS-T2WI) threshold of 40% in lesions characterising ferucarbotran-enhanced FS-T2WI, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value were 88.6%, 95%, 90.9%, 96.9% and 82.6%, respectively. In conclusion, with ferucarbotran-enhanced FS-T2WI, a PSIL(FS-T2WI) threshold of 40% for characterising focal liver nodules among patients with chronic liver disease is recommended. It is useful for distinguishing HCC from benign nodules.

The role of SPIO-enhanced MRI in the detection of malignant liver lesions

The aim of this study was to evaluate the efficacy of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) in the detection of malignant liver tumors. MRI, using fast spin-echo T(2)-weighted and gradient-echo T(1)-weighted imagings before and after SPIO infusion, was performed in 32 patients with known or suspected hepatic lesions. Statistical analysis was performed using lesion-by-lesion analysis. SPIO-enhanced T(2)-weighted MRI showed results comparable to those of unenhanced T(2)-weighted MRI in the detection of focal liver lesions.

Gradient- and spin-echo T2-weighted imaging for SPIO-enhanced detection and characterization of focal liver lesions

PURPOSE

To evaluate superparamagnetic iron oxide (SPIO)-enhanced breathhold T2-weighted GRASE imaging in detection and characterization of focal liver lesions.

MATERIALS AND METHODS

In 30 patients (including 20 with cirrhosis) with 39 malignant and 25 benign lesions, gradient- and spin-echo (GRASE) images with two echo times (75 and 90 msec; GRASE75 and GRASE90) were obtained prior to and following administration of SPIO, and compared with respiratory-triggered and breathhold fast spin-echo (RT-FSE and BH-FSE) images. Two readers evaluated image quality and reviewed 240 liver segments for sensitivity and specificity. Signal-to-noise ratio (SNR), and its reduction in liver and spleen after administration of SPIO, and lesion-to-liver contrast-to-noise ratio (CNR) were measured.

RESULTS

Compared with RT-FSE and BH-FSE, GRASE reduced scan time by 77% to 82% and 21% to 27%, respectively. The image qualities with BH-FSE and GRASE75 were higher than with BH-FSE and GRASE90. BH-FSE showed higher specificity than RT-FSE and GRASE90, but otherwise there were no significant differences between pulse sequences for sensitivity or specificity. The mean SNR and CNR of the lesions with RT-FSE were significantly higher than with the other methods. SPIO-induced signal reduction of liver SNR was smallest with BH-FSE.

CONCLUSION

GRASE is faster and more sensitive to SPIO than FSE, but its sensitivity and specificity were slightly inferior to those of BH-FSE. Image quality is a current limitation.

Magnetic resonance imaging features of focal liver lesions after intervention

The aim of this article is to provide an overview of MRI features of primary and secondary liver lesions after intervention. Emphasis is given to T2- and T1-weighted pre and post intravenous gadolinium chelates appearance of successfully treated lesions and, from residual/recurrent tumors after therapy. In addition, complications after procedures are briefly cited. Liver resection, radiation therapy, systemic chemotherapy, transcatheter arterial chemoembolization, ablative therapies and liver transplantation are the methods discussed in this review. Among these methods, special attention is given to MRI findings after ablative therapies since radiofrequency ablation is commonly performed in our institution.