Hepatocellular carcinoma after systemic chemotherapy: gadolinium-enhanced mr measurement of necrosis by volume histogram

Management implications and outcomes of LI-RADS-2, -3, -4, and -M category observations

A radiologist issuing a LI-RADS category is, implicitly or explicitly, a member of a multidisciplinary team. If the definite diagnosis of a benign or malignant entity is not possible, categorizing the uncertainty as LR-2, -3, -4, or -M has important management implications. In this article, we discuss the range of options for management or further diagnostic testing and how a LR category may affect the choice between them. We then review recent published data regarding eventual diagnoses following assignment of a LR category.

Magnetic resonance imaging of therapy-induced necrosis using gadolinium-chelated polyglutamic acids

PURPOSE

Necrosis is the most common morphologic alteration found in tumors and surrounding normal tissues after radiation therapy or chemotherapy. Accurate measurement of necrosis may provide an early indication of treatment efficacy or associated toxicity. The purpose of this report is to evaluate the selective accumulation of polymeric paramagnetic magnetic resonance (MR) contrast agents--gadolinium p-aminobenzyl-diethylenetriaminepentaacetic acid-poly(glutamic acid) (L-PG-DTPA-Gd and D-PG-DTPA-Gd)--in necrotic tissue.

METHODS AND MATERIALS

Two different solid tumor models, human Colo-205 xenograft and syngeneic murine OCA-1 ovarian tumors, were used in this study. Necrotic response was induced by treatment with poly(L-glutamic acid)-paclitaxel conjugate (PG-TXL). T(1)-weighted spin-echo images were obtained immediately and up to 4 days after contrast injection and compared with corresponding histologic specimens. Two low-molecular-weight contrast agents, DTPA-Gd and oligomeric(L-glutamic acid)-DTPA-Gd, were used as nonspecific controls.

RESULTS

Initially, there was minimal tumor enhancement after injection of either L-PG-DTPA-Gd or D-PG-DTPA-Gd, but rapid enhancement after injection of low-molecular-weight agents. However, polymeric contrast agents, but not low-molecular-weight contrast agents, caused sustained enhancement in regions of tumor necrosis in both tumors treated with PG-TXL and untreated tumors. These data indicate that high molecular weight, rather than in vivo biodegradation, is necessary for the specific localization of polymeric MR contrast agents to necrotic tissue. Moreover, biotinylated L-PG-DTPA-Gd colocalized with macrophages in the tumor necrotic areas, suggesting that selective accumulation of L- and D-PG-DTPA-Gd in necrotic tissue was mediated through residing macrophages.

CONCLUSIONS

Our data suggest that MR imaging with PG-DTPA-Gd may be a useful technique for noninvasive characterization of treatment-induced necrosis.

Pre-, peri-, and posttreatment imaging of liver lesions

This article provides an overview of current treatment approaches in patients with primary or secondary liver diseases. Emphasis is placed on MR imaging prior, during, and after various treatments, including liver resection, systemic chemotherapy, transcatheter arterial chemoembolization, ablative therapies, and liver transplantation. Findings described for MR imaging are directly applicable to findings for CT and potentially contrast-enhanced ultrasound. The authors' description, however, will deal mainly with MR imaging as this is the their preferred approach due to diagnostic accuracy and patient safety, and the findings are most demonstrative on MR imaging.

Dynamic contrast-enhanced MRI analysis of perfusion changes in advanced hepatocellular carcinoma treated with an antiangiogenic agent: a preliminary study

OBJECTIVE

To evaluate the perfusion changes in advanced hepatocellular carcinoma (HCC) treated with the antiangiogenic agent thalidomide, we used dynamic contrast-enhanced MRI.

SUBJECTS AND METHODS

Dynamic contrast-enhanced MRI was performed before and during thalidomide treatment in seven patients with advanced unresectable HCC that had failed to respond to prior local therapy. A turbo fast low-angle shot sequence was performed in a 1.5-T MR scanner. An operator-defined region of interest was placed in the maximal enhancement region of the tumor site and adjacent tumor-free parenchyma of all patients. A time-intensity curve was plotted and analyzed. The peak enhancement in the first-pass study, the maximal enhancement, and the initial enhancement slope percentage in the first-pass study of the tumor and parenchyma were measured. The changes in these three perfusion parameters were estimated and correlated with clinical outcomes. The seven patients were categorized into two groups on the basis of their clinical outcomes: group A patients were those who had progressive disease, whereas group B patients were those who had stable disease or partial response.

RESULTS

Four of the seven patients were classified as group A, and the other three were classified as group B patients. When comparing the MRI parameters for the tumors before and during treatment in group A and group B patients, we found a statistically significant difference for the peak enhancement in the first-pass study, the maximal enhancement, and the enhancement slope percentage in the first-pass study. When comparing the parenchymal parameters, we found a statistically significant difference in the maximal enhancement and borderline significance in the peak enhancement in the first-pass study (p = 0.057) between group A and group B patients.

CONCLUSION

The dynamic MRI parameters showed significant differences between two groups of patients with different clinical outcomes.