Shane A. Wells

Liver Ablation: Best Practice

Tumor ablation in the liver has evolved to become a well-accepted tool in the management of increasing complex oncologic patients. At present, percutaneous ablation is considered first-line therapy for very early and early hepatocellular carcinoma and second-line therapy for colorectal carcinoma liver metastasis. Because thermal ablation is a treatment option for other primary and secondary liver tumors, an understanding of the underlying tumor biology is important when weighing the potential benefits of ablation. This article reviews ablation modalities, indications, patient selection, and imaging surveillance, and emphasizes technique-specific considerations for the performance of percutaneous ablation.

Microwave versus Radiofrequency Ablation Treatment for Hepatocellular Carcinoma: A Comparison of Efficacy at a Single Center

PURPOSE To compare efficacy and major complication rates of radiofrequency (RF) and microwave (MW) ablation for treatment of hepatocellular carcinoma (HCC). MATERIALS AND METHODS This retrospective single-center study included 69 tumors in 55 patients treated by RF ablation and 136 tumors in 99 patients treated by MW ablation between 2001 and 2013. RF and MW ablation devices included straight 17-gauge applicators. Overall survival and rates of local tumor progression (LTP) were evaluated using Kaplan-Meier techniques with Cox proportional hazard ratio (HR) models and competing risk regression of LTP. RESULTS RF and MW cohorts were similar in age (P = .22), Model for End-Stage Liver Disease score (P = .24), and tumor size (mean 2.4 cm [range, 0.6-4.5 cm] and 2.2 cm [0.5-4.2 cm], P = .09). Median length of follow-up was 31 months for RF and 24 months for MW. Rate of LTP was 17.7% with RF and 8.8% with MW. Corresponding HR from Cox and competing risk models was 2.17 (95% confidence interval [CI], 1.04-4.50; P = 0.04) and 2.01 (95% CI, 0.95-4.26; P = .07), respectively. There was improved survival for patients treated with MW ablation, although this was not statistically significant (Cox HR, 1.59 [95% CI, 0.91-2.77; P = .103]). There were few major (≥ grade C) complications (2 for RF, 1 for MW; P = .28). CONCLUSIONS Treating HCC percutaneously with RF or MW ablation was associated with high primary efficacy and durable response, with lower rates of LTP after MW ablation.

Percutaneous microwave ablation of T1a and T1b renal cell carcinoma: short-term efficacy and complications with emphasis on tumor complexity and single session treatment

PurposeTo update the oncologic outcomes and safety for microwave (MW) ablation of T1a (≤4.0 cm) and T1b (4.1–7.0 cm) renal cell carcinoma (RCC) with emphasis on tumor complexity and single session treatment.Materials and MethodsRetrospective review of 29 consecutive patients (30 tumors) with localized (NOMO) RCC (23 T1a; 7 T1b) treated with percutaneous MW ablation between 3/2013 and 6/2014. Primary outcomes investigated were technical success, local tumor progression (LTP), and complications. Technical success was assessed with contrast-enhanced computed tomography (CECT) immediately after MW ablation. Presence of LTP was assessed with CECT or contrast-enhanced magnetic resonance at 6-month target intervals for the first two years and annually thereafter. Complications were categorized using the Clavien-Dindo classification system.ResultsMedian tumor diameter was 2.8 cm [IQR 2.1–3.3] for T1a and 4.7 cm [IQR 4.1–5.7] for T1b tumors. Median RENAL nephrometry score was 7 [IQR 4–8] for T1a tumors and 9 [IQR 6.25–9.75] for T1b tumors. Technical success was achieved for 22 T1a (96%) and 7 T1b (100%) tumors. There were no LTP during a median imaging follow-up of 12.0 months [IQR 6–18] for the 23 patients (24 tumors) with greater than 6 months of follow-up. There were three Clavien-Dindo grade I–II complication (10%) and no Clavien-Dindo grade III–V complications (0%). All but two patients (93%) are alive without metastatic disease; two patients died after 12-month follow-up of causes unrelated to the MW ablation.ConclusionPercutaneous MW ablation appears to be a safe and effective treatment option for low, moderate, and highly complex T1a and T1b RCC in early follow-up.

Effect of Tumor Complexity and Technique on Efficacy and Complications after Percutaneous Microwave Ablation of Stage T1a Renal Cell Carcinoma: A Single-Center, Retrospective Study

Purpose To evaluate the effects of tumor complexity and technique on early and midterm oncologic efficacy and rate of complications for 100 consecutive biopsy-proved stage T1a renal cell carcinomas (RCCs) treated with percutaneous microwave ablation. Materials and Methods This HIPAA-compliant, single-center retrospective study was approved by the institutional review board. The requirement to obtain informed consent was waived. Ninety-six consecutive patients (68 men, 28 women; mean age, 66 years ± 9.4) with 100 stage T1a N0M0 biopsy-proved RCCs (median diameter, 2.6 cm ± 0.8) underwent percutaneous microwave ablation between March 2011 and June 2015. Patient and procedural data were collected, including body mass index, comorbidities, tumor histologic characteristics and grade, RENAL nephrometry score, number of antennas, generator power, and duration of ablation. Technical success, local tumor progression, and presence of complications were assessed at immediate and follow-up imaging. The Kaplan-Meier method was used for survival analyses. Results Technical success was achieved for all 100 tumors (100%), including 47 moderately and five highly complex RCCs. Median clinical and imaging follow-up was 17 months (range, 0-48 months) and 15 months (range, 0-44 months), respectively. No change in estimated glomerular filtration rate was noted after the procedure (P = .49). There were three (3%) procedure-related complications and six (6%) delayed complications, all urinomas. One case of local tumor progression (1%) was identified 25 months after the procedure. Three-year local progression-free survival, cancer-specific survival, and overall survival were 88% (95% confidence interval: 0.52%, 0.97%), 100% (95% confidence interval: 1.0%, 1.0%), and 91% (95% confidence interval: 0.51%, 0.99%), respectively. Conclusion Percutaneous microwave ablation is an effective and safe treatment option for stage T1a RCC, regardless of tumor complexity. Long-term follow-up is needed to establish durable oncologic efficacy and survival relative to competing ablation modalities and surgery.

Automated Volumetric Assessment by Noncontrast Computed Tomography in the Surveillance of Nephrolithiasis

OBJECTIVE To evaluate the use of automated volumetric assessment for stone surveillance and compare the results with manual linear measurement. METHODS We retrospectively reviewed patients seen in our stone clinic who had undergone 2 noncontrast computed tomography (NCCT) scans without stone intervention during the interval between scans. Thirty patients met our inclusion criteria and underwent longitudinal assessment for urolithiasis via NCCT (mean interval 583.2 days, range 122-2030). Fifty-two discrete calculi were analyzed. Three board certified radiologists measured maximal linear stone size in the axial plane using electronic calipers on soft tissue (ST) and bone windows (BWs). Automated stone volume was also obtained by each reader using a dedicated prototype software tool for stone evaluation. RESULTS Mean stone linear size and volume was 4.9 ± 2.8 mm (ST), 4.5 ± 2.6 mm (BW), and 116.2 ± 194.6 mm(3) (window independent), respectively. Mean interobserver variability for linear size measurement was 16.4 ± 10.5% (ST) and 20.3 ± 13.8% (BW). Interobserver variability for volumetric measurement was 0%. Of the 52 persistent stones, the mean percent change in linear stone size between CT studies was 39.3 ± 46.7% (ST) and 42.9 ± 53.1% (BW) growth, compared with 171.4 ± 320.1% (window independent) growth for automated volume measurement over a mean of 583.2 days. However, discordant results for increased vs decreased interval size was seen between linear and volumetric assessment in 19/52 stones (36.5%). CONCLUSION Automated volumetric measurement of renal calculi via NCCT is independent of specific reader and window settings. Volumetric assessment amplifies smaller linear changes over time, whereas as much as one third of cases show linear-volume measurement discordance. Volumetric assessment is therefore preferable, particularly for longitudinal surveillance of renal calculi.

Hepatic Tumor Ablation.

Tumor ablation is a safe and effective treatment available in the multidisciplinary care of the surgical oncology patient. The role of ablation is well established in the treatment of hepatocellular carcinoma and is becoming more accepted in the treatment of various malignancies metastatic to the liver, in particular colorectal cancer. Understanding the underlying technology, achieving appropriate applicator placement, using maximum energy delivery to create margins, and performing necessary adjunctive maneuvers are all required for successful tumor ablation.

Comparative Analysis of Surgery, Thermal Ablation, and Active Surveillance for Renal Oncocytic Neoplasms

OBJECTIVE To compare oncological and procedural outcomes for renal oncocytic tumors treated with surgery, thermal ablation, or active surveillance. METHODS Clinical and pathologic data were collected for consecutive patients with a histologic diagnosis of oncocytoma, oncocytic neoplasm, or chromophobe renal cell cancer (chRCC) from 2003 to 2016. Independent pathology and radiology reviews were performed for this study. RESULTS Of 171 patients, tumor histology included oncocytoma (n = 122), chRCC (n = 47), and oncocytic neoplasm not otherwise specified (n = 2). At the initial diagnosis, 67, 14, and 90 patients were treated with surgery, thermal ablation, and active surveillance. In 3 of 19 patients (16%) who had biopsy and subsequent surgery, diagnosis changed from oncocytoma to chRCC. The median follow-up was 39.9 months with no difference among choices of treatment modalities (P = .33). Of 90 patients who began active surveillance, 32 (36%) switched to active treatments (19 underwent thermal ablation and 13 underwent surgery). The median linear growth rate for patients on active surveillance was 1.2 mm/y. No patients who were managed with active surveillance developed metastatic renal cell cancer (mRCC). mRCC was identified in 3 patients and was the cause of death in 2 patients. Patients who developed metastatic disease presented with symptomatic tumors of >4 cm and were treated with immediate surgery. For oncocytic masses of ≤4 cm (n = 126), the 5-year cancer-specific survival was 100%. CONCLUSION Renal oncocytic neoplasms have favorable oncological outcomes. Active surveillance is safe and is the preferred management for small (≤4 cm) oncocytic renal tumors in selected patients.

Delineation of Post-Procedure Ablation Regions with Electrode Displacement Elastography with a Comparison to Acoustic Radiation Force Impulse Imaging

We compared a quasi-static ultrasound elastography technique, referred to as electrode displacement elastography (EDE), with acoustic radiation force impulse imaging (ARFI) for monitoring microwave ablation (MWA) procedures on patients diagnosed with liver neoplasms. Forty-nine patients recruited to this study underwent EDE and ARFI with a Siemens Acuson S2000 system after an MWA procedure. On the basis of visualization results from two observers, the ablated region in ARFI images was recognizable on 20 patients on average in conjunction with B-mode imaging, whereas delineable ablation boundaries could be generated on 4 patients on average. With EDE, the ablated region was delineable on 40 patients on average, with less imaging depth dependence. Study of tissue-mimicking phantoms revealed that the ablation region dimensions measured on EDE and ARFI images were within 8%, whereas the image contrast and contrast-to-noise ratio with EDE was two to three times higher than that obtained with ARFI. This study indicated that EDE provided improved monitoring results for minimally invasive MWA in clinical procedures for liver cancer and metastases.

Safety and Efficacy of Percutaneous Microwave Hepatic Ablation Near the Heart

PURPOSE To evaluate safety and efficacy of percutaneous hepatic microwave (MW) ablation performed near the heart. MATERIALS AND METHODS This study reviewed 118 consecutive peripheral (ablation zone margins within 5 mm of liver capsule) percutaneous MW hepatic ablations performed between June 2010 and August 2015. Ablation zones of 27 tumors (22.8%) extended to ≤ 5 mm from myocardium, and these ablations comprised the study group; the remaining ablations formed the control group. The study cohort included 14 men and 10 women (mean age, 59 y) with 16 hepatocellular carcinomas, 9 metastases, and 2 hemangiomas. Periprocedural imaging was used to evaluate tumor size and distance from the heart, ablation zone size, and complications. Mean tumor size and distance to myocardium were 2.6 cm ± 1.7 and 1.1 cm ± 1.1, respectively. The electronic medical record was used to retrospectively assess local tumor progression (LTP) and electrocardiogram and hemodynamic alterations during and after ablation. Statistical analysis was performed with Fisher exact test and t test. RESULTS Median follow-up was 13.6 months (range, 1.2-38.7 months). No arrhythmias occurred during or after ablation in the follow-up period (0/27). There was no difference between groups in frequency of alterations in periprocedural blood pressure (25.9% vs 29.6%, p=0.81) or heart rate (18.5% vs 24.2%, P = .61) or rate of LTP (12.0% vs 10.8%, P = 1.0). CONCLUSIONS Percutaneous MW ablation near the heart may be safe and effective, without increased risk of cardiac complications and with similar rates of LTP, compared with a control group of peripheral liver ablations.

Percutaneous biopsy in the abdomen and pelvis: a step-by-step approach

Abstract Percutaneous abdominal biopsies provide referring physicians with valuable diagnostic and prognostic information that guides patient care. All biopsy procedures follow a similar process that begins with the preprocedure evaluation of the patient and ends with the postprocedure management of the patient. In this review, a step-by-step approach to both routine and challenging abdominal biopsies is covered with an emphasis on the differences in biopsy devices and imaging guidance modalities. Adjunctive techniques that may facilitate accessing a lesion in a difficult location or reduce procedure risk are described. An understanding of these concepts will help maintain the favorable safety profile and high diagnostic yield associated with percutaneous biopsies.