Emerging therapies for hepatocellular carcinoma: opportunities for radiologists

Advances in image-guided intratumoral drug delivery techniques

Image-guided drug delivery provides a means for treating a variety of diseases with minimal systemic involvement while concurrently monitoring treatment efficacy. These therapies are particularly useful to the field of interventional oncology, where elevation of tumor drug levels, reduction of systemic side effects and post-therapy assessment are essential. This review highlights three such image-guided procedures: transarterial chemoembolization, drug-eluting implants and convection-enhanced delivery. Advancements in medical imaging technology have resulted in a growing number of new applications, including image-guided drug delivery. This minimally invasive approach provides a comprehensive answer to many challenges with local drug delivery. Future evolution of imaging devices, image-acquisition techniques and multifunctional delivery agents will lead to a paradigm shift in patient care.

Chemo-embolization for unresectable hepatocellular carcinoma with different sizes of embolization particles

The purpose of this study was to evaluate the size responses and vascular responses to three different sizes of Embosphere (EMBS) embolization particles used for chemo-embolization in patients with unresectable hepatocellular carcinoma (HCC). Forty-seven patients with biopsy proven HCC treated with TACE using EMBS (Biosphere Medical, Rockland, MA, USA) were included in this study. EMBS are non-resorbable tris-acryl gelatin defined-size microspheres. Sixteen patients were treated with 40-120 micron (40-microm), 13 patients with 100-300 (100-microm), and 18 patients with 300-500 (300-microm) EMBS particles. We measured the two-dimensional area and vascularity of the tumor index lesion on initial and subsequent CTs after treatment. Lesions were classified into four grades based on the degree of vascularity measured in 25% increments. Size of tumor after one treatment decreased by an average (avg) of 18% for 40-120-microm particles, 38% for 100-300-microm particles, and 17% for 300-500-microm particles. After three treatments, size decreased by an avg of 46% for 40-120-microm particles, 76% for 100-300-microm particles, and 46% for 300-500-microm particles. Vascularity decrease was also measured after the first and third treatments, and defined as a decrease of one or more grades in tumor vascularity. Results were as follows (% of patients with decrease). For 40-120-microm particles: 1 and 3 treatments, 53% and 88% of patients. For 100-300-microm particles: 1 and 3 treatments, 60% and 88% of patients. For 300-500-microm particles: 1 and 3 treatments, 50% and 57% of patients. It was concluded the 100-300-microm EMBS particles produce slightly higher responses.

Vascular Guide Wire Navigation with a Magnetic Guidance System: Experimental Results in a Phantom

PURPOSE

To investigate the efficacy of a second-generation prototype magnetic guidance system in complex vessel phantoms versus conventional navigation in simulated interventional radiology procedures and to analyze procedure and fluoroscopy times.

MATERIALS AND METHODS

The magnetic guidance system consists of two focused-field permanent magnets on each side of the body that create a 0.1-T navigation field and is integrated with a modified C-arm single-planar digital angiography system. Forty-nine navigations in a glass phantom and 80 navigations in a three-dimensional liver phantom were performed with a magnetically tipped floppy 0.014-inch guide wire and a conventional 0.014-inch microcatheter system. Rates of success and fluoroscopy and procedure times were quantified for both techniques. For the liver phantom experiment, the Mann-Whitney U test was used. For the glass phantom experiment, the Wilcoxon matched pair test was used with the Hodges-Lehmann estimator.

RESULTS

In the glass phantom experiments, 42 of 49 turns were successfully performed with both methods. Procedure time to reach a target did not differ significantly between methods, while fluoroscopy time was significantly different when compared with that of the magnetic guidance system (P <.01). Navigation in the liver phantom was successful in 80 of 80 turns with the magnetic guidance system and in 76 of 80 turns with conventional navigation. With the support of the magnetic guidance system, procedure time and fluoroscopy time were significantly different from those with conventional navigation (P <.001).

CONCLUSION

The magnetic guidance system allows the precise navigation of a magnetic guide wire in complex vessel phantoms with significantly shorter fluoroscopy and procedure times.

Influence of large peritumoral vessels on outcome of radiofrequency ablation of liver tumors

PURPOSE

The effect of large vessels (>/=3 mm) contiguous to hepatic tumors was evaluated with respect to clinical tumor recurrence rates after radiofrequency (RF) ablation.

MATERIALS AND METHODS

The first 105 malignant liver tumors treated by RF ablation therapy at our institution with pathologic analysis or a minimum of 6 months of clinical follow-up were reviewed. The original pretreatment imaging studies were reviewed by a radiologist who was blinded to the cases, and, based on lesion contiguity to vessels of at least 3 mm, the lesions were categorized as perivascular or nonperivascular. Treatment outcomes with respect to local tumor recurrence between these two groups were then compared. Logistic regression analysis was performed to take into account other variables and to determine whether this categorization was an independent predictor of treatment outcome.

RESULTS

There were 74 nonperivascular tumors and 31 perivascular tumors. Mean tumor size was 2.4 cm and mean follow-up was 11.3 months. Residual or locally recurrent tumors were documented in 20 of 105 cases (19%). In the nonperivascular group, five of 74 (7%) had either incompletely treated tumor (manifested within 6 months) or local recurrence beyond 6 months. In the perivascular group, 15 of 31 (48%) had incompletely treated or locally recurrent tumor (P <.001). Subanalysis of lesion size (61 tumors </=2.5 cm, 33 tumors 2.6-4 cm, and 11 tumors >4 cm), tumor type (40 hepatocellular carcinomas, 48 colorectal metastases, and 17 other metastases), access (53 intraoperative, 52 percutaneous), and RF device (45 Radiotherapeutics electrodes, 18 Rita electrodes, and 42 Radionics electrodes) showed similar results. Multivariate logistic regression analysis showed that presence or absence of a large peritumoral vessel is an independent, and the dominant, predictor of treatment outcome.

CONCLUSION

The presence of vessels at least 3 mm in size contiguous to hepatic tumors is a strong independent predictor of incomplete tumor destruction by RF ablation. Modified ablation strategies should be considered to improve destruction of these tumors.