MRI contrast enhancement of malignant liver tumours following successful cryoablation

Multimodality Imaging of Hepatocellular Carcinoma: From Diagnosis to Treatment Response Assessment in Everyday Clinical Practice

The Liver Imaging Reporting and Data System (LI-RADS) is a recently developed classification aiming to improve the standardization of liver imaging assessment in patients at risk of developing hepatocellular carcinoma (HCC). The LI-RADS v2017 implemented new algorithms for ultrasound (US) screening and surveillance, contrast-enhanced US diagnosis and computed tomography/magnetic resonance imaging treatment response assessment. A minor update of LI-RADS was released in 2018 to comply with the American Association for the Study of the Liver Diseases guidance recommendations. The scope of this review is to provide a practical overview of LI-RADS v2018 focused both on the multimodality HCC diagnosis and treatment response assessment.

Imaging findings during and after percutaneous cryoablation of hepatic tumors

OBJECTIVE

Imaging plays a key role in the assessment of patients before, during, and after percutaneous cryoablation of hepatic tumors. Intra-procedural and early post-procedure imaging with CT and MRI is vital to the assessment of technical success including adequacy of ablation zone coverage. Recognition of the normal expected post-procedure findings of hepatic cryoablation such as ice ball formation, hydrodissection, and the normal appearance of the ablation zone is crucial to be able to differentiate from complications including vascular, biliary, or non-target organ injury. Delayed imaging is essential for determination of clinical effectiveness and detection of unexpected findings such as residual unablated tumor and local tumor progression. The purpose of this article is to review the spectrum of expected and unexpected imaging findings that may occur during or after percutaneous cryoablation of hepatic tumors.

CONCLUSION

Differentiating expected from unexpected findings during and after hepatic cryoablation helps radiologists identify residual or recurrent tumor and detect procedure-related complications.

Bioluminescence Image as a Quantitative Imaging Biomarker for Preclinical Evaluation of Cryoablation in a Murine Model

PURPOSE

To employ bioluminescence imaging (BLI) as a quantitative imaging biomarker to assess preclinical evaluation of cryoablation in a murine model.

MATERIALS AND METHODS

In vitro, Colon26-Luc (C26-Luc) cells were seeded at 6 different concentrations in 35-mm dishes. These were divided into 6 groups: group 0 (G0), a control group without treatment; and groups 1-5 (G1-G5) according to the number of freeze-thaw cycles, with each cycle consisting of freezing at -80°C for 10 min followed by thawing at room temperature for 5 minutes. BLI and flow-cytometric analysis were performed after cryotherapy. In vivo, 20 tumor-bearing mice with C26-Luc cells were divided into 4 groups: group 0 (G0), a control group; and groups 1-3 (G1-G3) according to the number of freeze-thaw cycles. Each cryoablation procedure was performed for 30 seconds with liquid nitrogen (-170°C) applied with cotton-tipped applicators. BLI was acquired at 6 hours and 1, 3, and 7 days after treatments.

RESULTS

In vitro, BLI signal showed a negative correlation with the number of freeze-thaw cycles (r = -0.86, P = .02). In vivo, there was no difference in tumor volume at 1 day after cryoablation among all groups, but the BLI signals were significantly different between G0 and G2/G3 (P = .03 and P = .02, respectively) and between G1 and G3 (P = .04). BLI signals reflected tumor growth speed and survival ratio.

CONCLUSIONS

This study demonstrates the direct validation of BLI as a quantitative tool for the early assessment of therapeutic effects of cryoablation.

Locoregional therapies for hepatocellular carcinoma and the new LI-RADS treatment response algorithm

Radiologists play a central role in the assessment of patient response to locoregional therapies for hepatocellular carcinoma (HCC). The identification of viable tumor following treatment guides further management and potentially affects transplantation eligibility. Liver Imaging Reporting and Data Systems (LI-RADS) first introduced the concept of LR-treated in 2014, and a new treatment response algorithm is included in the 2017 update to assist radiologists in image interpretation of HCC after locoregional therapy. In addition to offering imaging criteria for viable and nonviable HCC, new concepts of nonevaluable tumors as well as tumors with equivocal viability are introduced. Existing guidelines provided by response evaluation criteria in solid tumors (RECIST) and modified RECIST address patient-level assessments and are routinely used in clinical trials but do not address the variable appearances following different locoregional therapies. The new LI-RADS treatment response algorithm addresses this gap and offers a comprehensive approach to assess treatment response for individual lesions after a variety of locoregional therapies, using either contrast-enhanced CT or MRI.

Incidence of Post-ablation Syndrome Following Image-Guided Percutaneous Cryoablation of Renal Cell Carcinoma: A Prospective Study

PURPOSE

To prospectively evaluate the incidence of post-ablation syndrome (fever and flu-like symptoms) and impact on the quality of life in the first 10 days following percutaneous image-guided cryoablation for renal cell carcinoma (RCC).

MATERIALS AND METHODS

A prospective study of all cryoablation procedures with biopsy proven RCC was conducted with institutional review board approval between 08/2012 and 04/2016. Sixty-four patients (43 males and 21 females) underwent cryoablation. Mean age was 68 (range 24-86). A telephone questionnaire survey was conducted on days 1, 3, 5, 7 and 10 following cryoablation, and complications were recorded. Data collected included temperature, degree of flu-like symptoms, severity of pain, percentage of pain relief with analgesics, interference with general activity and with work (graded on a 0-10 Numeric Intensity Scale).

RESULTS

Following cryoablation, six patients (9%) out of 64 developed post-ablation syndrome. Thirty-three patients (52%) developed flu-like symptoms only, which completely resolved by day 10 in 25 patients (39%). One patient had pyrexia only, which was self- limiting by day 10. Twenty-four patients (38%) were asymptomatic. Pain (mean score = 2.1) and interference on general activities (mean score = 1.8) and work (mean score = 2) following cryoablation peaked on day 3 and improved subsequently. Forty-six patients (72%) had 90-100% pain relief by day 10. No major complications were observed.

CONCLUSION

The full spectrum of post-ablation syndrome following cryoablation occurs in approximately 9% of patients; however, 61% of patients experience flu-like symptoms in the first 10 days, which are self-limiting.

Clinical Practice Guidelines for Cryosurgery of Pancreatic Cancer: A Consensus Statement From the China Cooperative Group of Cryosurgery on Pancreatic Cancer, International Society of Cryosurgery, and Asian Society of Cryosurgery

Pancreatic cancer (PC), one of the most lethal malignancies, accounts for 8% to 10% of digestive system cancers, and the incidence is increasing. Surgery, chemotherapy, and radiotherapy have been the main treatment methods but are not very effective. Cryosurgery was first used in 1984 for treatment of locally advanced PC and has since become a considerable treatment for most cases of unresectable PC. During the past decade, cryosurgery has been applied in some hospitals in China, and the newly developed technique of computed tomography- and/or ultrasound-guided percutaneous cryosurgery has shown better results than chemotherapy in cases of unresectable locally advanced PC, with the 1-year survival rate reported to be more than 50%. To develop standardized criteria for the application of cryosurgery in PC, the International Society of Cryosurgery and Asian Society of Cryosurgery assembled experts from Austria, Japan, and China to discuss treatment methods and arrive at a consensus on the indications, contraindications, and preferred techniques of PC cryosurgery.

Therapy Monitoring with Functional and Molecular MR Imaging

Cancer therapy is mainly based on different combinations of surgery, radiotherapy, and chemotherapy. Additionally, targeted therapies (designed to disrupt specific tumor hallmarks, such as angiogenesis, metabolism, proliferation, invasiveness, and immune evasion), hormonotherapy, immunotherapy, and interventional techniques have emerged as alternative oncologic treatments. Conventional imaging techniques and current response criteria do not always provide the necessary information regarding therapy success particularly to targeted therapies. In this setting, MR imaging offers an attractive combination of anatomic, physiologic, and molecular information, which may surpass these limitations, and is being increasingly used for therapy response assessment.

Percutaneous imaging-guided cryoablation of liver tumors: predicting local progression on 24-hour MRI

OBJECTIVE

The purpose of this study was to determine which MRI features observed 24 hours after technically successful percutaneous cryoablation of liver tumors predict subsequent local tumor progression and to describe the evolution of imaging findings after cryoablation.

MATERIALS AND METHODS

Thirty-nine adult patients underwent technically successful imaging-guided percutaneous cryoablation of 54 liver tumors (hepatocellular carcinoma, 8; metastases, 46). MRI features pertaining to the tumor, ablation margin, and surrounding liver 24 hours after treatment were assessed independently by two readers. Fisher exact or Wilcoxon rank sum tests (significant p values < 0.05) were used to compare imaging features in patients with and without subsequent local tumor progression. Imaging features of the ablation margin, treated tumor, and surrounding liver were evaluated on serial MRI in the following year.

RESULTS

A minimum ablation margin of 3 mm or less was observed in 11 (78.6%) of 14 tumors with and 15 of 40 (37.5%) without progression (p = 0.012). A blood vessel bridging the ablation margin was noted in 11 of 14 (78.6%) tumors with and nine of 40 (22.5%) without progression (p < 0.001). The incidence of tumor enhancement 24 hours after cryoablation was similar for tumors with (10/14, 71.4%) or without (25/40, 62.5%) local progression (p = 0.75). MRI enabled assessment of the entire cryoablation margin in 49 of 54 (90.7%) treated tumors.

CONCLUSION

MRI features at 24 hours after liver cryoablation that were predictive of local tumor progression included a minimum ablation margin less than or equal to 3 mm and a blood vessel bridging the ablation margin. Persistent tumor enhancement is common after liver cryoablation and does not predict local tumor progression.

Percutaneous laser ablation of metastatic lymph nodes in the neck from papillary thyroid carcinoma: preliminary results

CONTEXT

Percutaneous laser ablation (PLA) may be useful in treating patients with metachronous metastatic lymph nodes in the neck.

OBJECTIVE

Our objective was to assess PLA as a treatment of difficult-to-treat metachronous cervical lymph node metastases from papillary thyroid carcinoma.

DESIGN AND SETTING

We conducted a retrospective analysis of prospectively collected data at a public hospital.

PATIENTS

Fifteen patients with previous resection of papillary thyroid carcinoma with elevated serum levels of thyroglobulin (Tg) or anti-Tg antibodies (TgAbs) and 24 metachronous nodal metastases treated between September 2010 and April 2012 were followed with [¹⁸F]fluorodeoxyglucose (¹⁸FDG) positron emission tomography (PET)/computed tomography (CT) and contrast-enhanced ultrasound (CEUS).

INTERVENTION

Intervention was PLA.

OUTCOME MEASURES

Technique feasibility and technical success were evaluated. Tg/TgAb serum levels and ¹⁸FDG-PET/CT, and CEUS appearance were assessed at 6 and 12 months and compared with baseline. Complications were recorded.

RESULTS

PLA was always feasible, and technical success was achieved in all patients. At 6 months, local control was achieved in 11 of 15 patients (73%), with 6 (40%) having serum Tg/TgAb normalized (P = .017 vs baseline). Whereas 20 of 24 (83%) nodes were negative at ¹⁸FDG-PET/CT and CEUS (P < .001 vs baseline), 4 were ¹⁸FDG-PET/CT-positive (3 also CEUS-positive). At the 12-month follow-up, local control was achieved in 10 of 14 patients (71.4%). Sixteen of 20 nodes (80%) were negative at ¹⁸FDG-PET/CT and CEUS (P < .001 vs baseline), 4 were ¹⁸FDG-PET/CT-positive (2 also CEUS-positive). Four of 10 (40%) patients had normalization of serum Tg/TgAb (P = .098 vs baseline). No major complications occurred.

CONCLUSIONS

PLA is potentially feasible, safe, and effective for the treatment of metachronous cervical nodal metastases from papillary thyroid carcinoma. This procedure may reduce or delay a large number of highly invasive repeat neck dissections.