Multimodality imaging following 90Y radioembolization: a comprehensive review and pictorial essay.

Radioembolization with yttrium 90 (90Y) microspheres represents an emerging transarterial therapy for the treatment of liver malignancies that continues to generate interest in the medical community. The classic indication of treatment response is a reduction in tumor size; however, parenchymal changes (eg, necrosis, lack of enhancement, specific findings at positron emission tomography and functional magnetic resonance imaging) and other benign findings (pleural effusions, perivascular edema, contralateral hypertrophy, ring enhancement, perihepatic fluid, fibrosis) may occur following treatment, requiring proper image interpretation. With classic imaging findings and surrogates (time to progression, duration of response, disease-free interval), response rates range from 20% to 80% in patients treated for hepatocellular carcinoma or metastatic disease to the liver. Complications of 90Y radioembolization include cholecystitis, abscess, and bilomas and should be recognized early in the imaging follow-up of these patients. Radiologists who are involved in the posttreatment assessment of patients undergoing 90Y radioembolization should be familiar with the imaging findings and potential imaging pitfalls associated with this therapy.

Rabbit VX2 tumors as an animal model of uterine fibroids and for uterine artery embolization.

PURPOSE: To determine the suitability of the rabbit VX2 tumor animal model for uterine fibroids and uterine artery embolization (UAE). MATERIALS AND METHODS: The authors implanted and grew one uterine VX2 tumor per rabbit in six rabbits. UAE was performed by using 100-300 microm embolic particles and confirmed with x-ray digital subtraction angiography, magnetic resonance (MR) imaging, and necropsy. Unenhanced and contrast medium-enhanced MR images of VX2 tumors were obtained before and after UAE. Relative MR signal-to noise-ratio (SNR) was measured in the uterine VX2 tumor and in normal uterine tissue before and after UAE and compared by using a paired t-test (P = .05). RESULTS: VX2 uterine tumors were successfully grown, and both VX2 tumor presence in the uterus and UAE were seen angiographically and confirmed with necropsy in all six rabbits. Statistically significant reductions in relative SNRs were measured in tumors (SNR before UAE, 15.3 +/- 5.15; SNR after UAE, 3.84 +/- 3.94; P < .0001). No statistically significant decrease in SNR was measured in normal uterine tissue before and after UAE (P = .63 for the right uterine horn and P = .93 for the left uterine horn). CONCLUSION: Rabbit VX2 uterine tumors may be a suitable animal model of uterine fibroids and UAE.

Biliary sequelae following radioembolization with Yttrium-90 microspheres.

PURPOSE: Yttrium-90 (90Y) radioembolization has emerged as a promising and safe therapeutic modality for patients with hepatocellular carcinoma (HCC) or metastatic liver cancer. The present report describes biliary sequelae following intraarterial 90Y therapy in patients with HCC or liver metastases. MATERIALS AND METHODS: All patients were treated with 90Y therapy according to standard lobar treatment protocol. Pre- and posttreatment imaging, liver function tests, and serum total bilirubin measurements were performed. Three to 6 months after treatment, biliary sequelae were evaluated with computed tomography and magnetic resonance imaging, and any liver-related laboratory adverse events were noted. RESULTS: A total of 327 patients (HCC, n=190; liver metastases, n=137) received 569 infusions of 90Y. At follow-up imaging, 33 patients (10.1%; liver metastases, n=26; HCC, n=7) had 40 imaging findings related to the biliary tree, including biliary necrosis (n=17), biloma (n=3), cholecystitis (n=2), gallbladder wall enhancement (n=6), gallbladder wall rent (n=3), abscess (n=1), and stricture (n=8). A total of 31 patients exhibited grade 3/4 bilirubin toxicities (13 [6.8%] with HCC, 18 [13.1%] with liver metastases). Unplanned interventions prompted by biliary sequelae were necessary in six of 327 patients (1.8%). CONCLUSIONS: 90Y therapy in patients with HCC or metastatic disease to the liver is associated with an acceptable rate of biliary toxicities. Further studies assessing long-term biliary sequelae are warranted.

Liver tumors: monitoring embolization in rabbits with VX2 tumors--transcatheter intraarterial first-pass perfusion MR imaging.

PURPOSE: To prospectively test the hypothesis that transcatheter intraarterial first-pass perfusion (TRIP) magnetic resonance (MR) imaging can depict serial reductions in rabbit liver tumor perfusion during transcatheter arterial embolization (TAE). MATERIALS AND METHODS: All experiments had institutional animal care and use committee approval. In four rabbits implanted with eight VX2 liver tumors, catheters were positioned in the hepatic arteries with conventional angiographic guidance. After transfer to the MR imaging suite, serial TAE was performed, with approximately 0.5 million 40-120-microm embolic particles injected at each embolic stage. TRIP MR imaging was performed at baseline and after each subsequent embolic stage (10 minutes between stages). Serial TAE and TRIP MR imaging were repeated until stasis. The first-pass time course of signal enhancement was measured in both tumors and hepatic arteries. Tumor area under the curve (AUC) and maximum upslope (MUS) values, each normalized by arterial input, were measured to assess iterative perfusion reduction. Perfusion measurements across TAE stages were compared with paired t tests and linear regression. RESULTS: AUC decreased from a pre-TAE baseline of 0.408 (95% confidence interval [CI]: 0.330, 0.486) to 0.065 (95% CI: 0.046, 0.085) (P<.001) after TAE. MUS decreased from a pre-TAE baseline of 0.151 (95% CI: 0.121, 0.181) to 0.027 (95% CI: 0.022, 0.031) (P<.001) after TAE. Reductions to AUC and MUS after each embolic stage were statistically significant (P<.006 for each group of paired comparisons). AUC strongly correlated with MUS (r=0.966, P<.001). CONCLUSION: TRIP MR imaging can depict serial reductions in liver tumor perfusion during TAE. TRIP MR imaging offers the potential to target functional embolic end points during TAE.

90Y radioembolization of metastatic breast cancer to the liver: toxicity, imaging response, survival.

PURPOSE: To present data from patients with breast cancer liver metastases who underwent radioembolization with yttrium (90Y) microspheres. MATERIALS AND METHODS: Using standard 90Y lobar treatment protocol, 27 female patients with progressing liver metastases on standard of care polychemotherapy were treated under an open-label phase 2 protocol. After treatment, we assessed (a) tumor response using computed tomography and/or positron emission tomography, (b) biochemical toxicity, and (c) survival. RESULTS: The mean age of the patients was 52. Seventeen (63%) patients received 20 left lobe treatments (median radiation dose, 123 Gy; mean, 119 Gy), and 20 (74%) patients received 22 right lobe treatments (median radiation dose, 121 Gy; mean, 109 Gy) to the treatment site. No significant dose-difference was noted between the two lobes (P=.69). Tumor response on 90-day follow-up computed tomography showed (a) complete and partial response in nine (39.1%) patients, (b) stable disease in 12 (52.1%) patients, and (c) progressive disease in 2 (8.8%) patients. Positive tumor response on positron emission tomography was noted in 17 (63%) patients. Three of 27 (11%) patients (Eastern Cooperation Oncology Group 1, 2, or 3) showed bilirubin toxicity of grade 3, all of which were attributed to disease progression. Median survival for Eastern Cooperation Oncology Group 0 versus 1, 2, or 3 patients was 6.8 months and 2.6 months, respectively (P=.24) and for patients with tumor burden<25% versus >25% was 9.4 and 2.0 months, respectively (P=.46). CONCLUSIONS: Radioembolization with 90Y brachytherapy device may be a viable therapeutic option for the treatment of breast cancer liver metastases in patients who have progressed or failed on standard of care polychemotherapy.