Yield of Routine Image-Guided Biopsy of Renal Mass Thermal Ablation Zones: 11-Year Experience.

PURPOSE: To determine the yield of routine image-guided core biopsy of renal cell carcinoma (RCC) thermal ablation zones. METHODS: Institutional review board approval was obtained for this Health Insurance Portability and Accountability Act-compliant quality improvement effort. Routine core biopsy of RCC ablation zones was performed 2 months postablation from July 2003 to December 2014. Routine nicotinamide adenine dinucleotide staining was performed by specialized genitourinary pathologists to assess cell viability. The original purpose of performing routine postablation biopsy was to verify, in addition to imaging, whether the mass was completely treated. Imaging was stratified as negative, indeterminate, or positive for viable malignancy. Histology was stratified as negative, indeterminate, positive, or nondiagnostic for viable malignancy. Histology results were compared to prebiopsy imaging findings. RESULTS: Routine ablation zone biopsy was performed after 50% (146/292) of index ablations (24 cryoablations, 122 radiofrequency ablations), and postablation imaging was performed more often with multiphasic computed tomography than magnetic resonance imaging (100 vs 46, p < 0.0001). When imaging was negative (n = 117), biopsy added no additional information (92% [n = 108] negative, 0.9% [n = 1] indeterminate, 7% [n = 8] nondiagnostic). When imaging was indeterminate (n = 19), 11% (n = 2) of biopsies had viable RCC and 89% (n = 17) were negative. When imaging was positive, biopsy detected viable neoplasm in only 10% (1/10) of cases; 80% (8/10) were negative and 10% (1/10) were nondiagnostic. CONCLUSION: Routine biopsy of renal ablation zones to validate postablation imaging results was not value-added and therefore was discontinued at the study institution.

Prevalence of malignancy in thyroid nodules with an initial nondiagnostic result after ultrasound guided fine needle aspiration.

The objective of this study was to determine the rate of malignancy in thyroid nodules with an initial nondiagnostic fine needle aspiration. From October 2001 to April 2007, biopsies were performed on 1344 thyroid nodules in our practice. Biopsies were performed on nodules using 25-27 gauge needles, ultrasound guidance and multiple passes using both suction and capillary action. We retrospectively reviewed the results of these biopsies as well as any further management of nodules that received nondiagnostic results (IRB HUM00006459). Following initial biopsy, 295/1344 (21.9%) of nodules received nondiagnostic pathologic results. Of this population, 39 nodules (13.1%) were lost to follow-up. Of the remaining 256 nodules that received a repeat FNA, surgical excision, or greater than 24 months of clinical and imaging follow-up, only five cancers were detected, representing only 2% of the population that received an initial nondiagnostic biopsy result. All of these cancers were papillary neoplasms. When rigorous, ultrasound-guided, fine needle aspiration of thyroid nodules is performed, a nondiagnostic histopathologic result should not be interpreted as suspicious for thyroid cancer. Given the low rate of malignancy in this population (2%), we suggest that clinical and imaging follow-up of these nodules, opposed to repeat sampling, is warranted.

MRI and CT characteristics of successfully ablated renal masses: Imaging surveillance after radiofrequency ablation.

OBJECTIVE: The objective of our study was to evaluate the evolution of the appearances of successfully ablated renal masses on CT and MRI. MATERIALS AND METHODS: We conducted a retrospective review of 28 solid renal masses in 25 patients who underwent percutaneous radiofrequency ablation (RFA) between July 2003 and July 2006 in whom there was no evidence of residual tumor during at least 1 year of imaging follow-up and there was postablation biopsy proof of nonviable tissue within the ablation cavity. Three radiologists assessed the size, morphology, and CT or MRI characteristics of the initial tumor and of the ablated tumor or ablation cavity at imaging follow-up 1-2, 3-5, 6-11, and 12-24 months after RFA. RESULTS: The mean initial tumor volume was 5.5 cm(3) (range, 0.3-22.3 cm(3)). Within 1-2 months, the postablation beds of small masses (< or = 3 cm(3)) were larger than the volume of the initial tumor. Large masses (> 3 cm(3)) did not show this increase in volume. At 12 months after RFA, the postablation beds had decreased in size but had not disappeared. On CT, the postablation beds did not show enhancement at any time. On MRI, the postablation beds often showed a thin rim of peripheral enhancement. Imaging follow-up often revealed local stranding in the perinephric fat adjacent to the ablation site. Exophytic tumors were more likely to separate from the renal parenchyma as they contracted toward their epicenter and were more likely to reveal a complete halo of soft-tissue attenuation in the adjacent perinephric fat, which became more apparent on the longer-term follow-up imaging studies. CONCLUSION: Successfully ablated tumors show predictable imaging features that can be used to guide interpretation of CT and MRI surveillance examinations.

Lack of tumor seeding of hepatocellular carcinoma after percutaneous needle biopsy using coaxial cutting needle technique.

OBJECTIVE: The objective of our study was to determine the incidence of tumor seeding after biopsy of hepatocellular carcinoma (HCC) using a coaxial cutting needle technique. Seeding along the needle track is a dreaded complication of percutaneous biopsy in patients with HCC, particularly in potential liver transplant recipients. Reported seeding rates range from 0.6% to 5.1% using various biopsy techniques. To our knowledge, the rate of seeding using a coaxial cutting needle technique has not been reported. MATERIALS AND METHODS: Retrospective review identified 128 patients with imaging-guided percutaneous liver biopsies positive for HCC. A coaxial cutting needle technique was uniformly used with a 17-gauge introducer and 18-gauge biopsy needle. Radiology and clinical reports were reviewed, and findings at clinical and imaging follow-up were assessed. RESULTS: During the 6-year study period, 1,012 liver mass biopsies were performed, with 128 positive for HCC (100 men and 28 women; average age, 58.4 years). One hundred one patients had more than 30 days of clinical or imaging follow-up (or both) after biopsy (mean, 410 days; range, 33-1,989 days) and constituted the study population. The remaining 27 were excluded because of inadequate follow-up. No suspected or confirmed tumor seeding on imaging, physical examination, or laparotomy was identified. CONCLUSION: We found no tumor seeding after percutaneous biopsy of HCC using a coaxial cutting needle technique. This rate, 0%, is lower than those reported with other techniques. The use of a needle introducer that remains in position during multiple cutting needle passes protects normal tissue along the track and may reduce seeding. This has particular importance for patients with stage I-II HCC, for whom liver transplantation may be curative.