James Louis Hinshaw

Microwave Ablation of Hepatic Malignancy

Microwave ablation is an extremely promising heat-based thermal ablation modality that has particular applicability in treating hepatic malignancies. Microwaves can generate very high temperatures in very short time periods, potentially leading to improved treatment efficiency and larger ablation zones. As the available technology continues to improve, microwave ablation is emerging as a valuable alternative to radiofrequency ablation in the treatment of hepatic malignancies. This article reviews the current state of microwave ablation including technical and clinical considerations.

Microwave ablation of malignant hepatic tumours: Intraperitoneal fluid instillation prevents collateral damage and allows more aggressive case selection

Abstract Purpose: Theaim of this peper was to retrospectively review our experience utilising protective fluid instillation techniques during percutaneous microwave ablation of liver tumours to determine if fluid instillation prevents non-target injuries and allows a more aggressive case selection. Materials and methods: This institute review board-approved, US Health Insurance Portability and Accountability Act-compliant, retrospective study reviewed percutaneous microwave ablation of 151 malignant hepatic tumours in 87 patients, comparing cases in which protective fluid instillation was performed with those where no fluid was utilised. In cases utilising hydrodisplacement for bowel protection, a consensus panel evaluated eligibility for potential ablation without hydrodisplacement. Patient age, tumour size, local tumour progression rate, length of follow-up, complications, displacement distance/artificial ascites thickness, and treatment power/time were compared. Results: Fluid administration was utilised during treatment in 29/151 of cases: 10/29 for protection of bowel (8/10 cases not possible without fluid displacement), and 19/29 for body wall/diaphragm protection. Local tumour progression was higher when hydrodisplacement was used to protect bowel tissue; this may be due to lower applied power due to operator caution. Local tumour progression was not increased for artificial ascites. There was no difference in complications between the fluid group and controls. Conclusion: Intraperitoneal fluid administration is a safe and effective method of protecting non-target structures during percutaneous hepatic microwave ablation. While hydrodisplacement for bowel protection allows more aggressive case selection, these cases were associated with higher rates of local tumour progression.

Microwave Ablation: Comparison of Simultaneous and Sequential Activation of Multiple Antennas in Liver Model Systems

PURPOSE To compare microwave ablation zones created by using sequential or simultaneous power delivery in ex vivo and in vivo liver tissue. MATERIALS AND METHODS All procedures were approved by the institutional animal care and use committee. Microwave ablations were performed in both ex vivo and in vivo liver models with a 2.45-GHz system capable of powering up to three antennas simultaneously. Two- and three-antenna arrays were evaluated in each model. Sequential and simultaneous ablations were created by delivering power (50 W ex vivo, 65 W in vivo) for 5 minutes per antenna (10 and 15 minutes total ablation time for sequential ablations, 5 minutes for simultaneous ablations). Thirty-two ablations were performed in ex vivo bovine livers (eight per group) and 28 in the livers of eight swine in vivo (seven per group). Ablation zone size and circularity metrics were determined from ablations excised postmortem. Mixed effects modeling was used to evaluate the influence of power delivery, number of antennas, and tissue type. RESULTS On average, ablations created by using the simultaneous power delivery technique were larger than those with the sequential technique (P < .05). Simultaneous ablations were also more circular than sequential ablations (P = .0001). Larger and more circular ablations were achieved with three antennas compared with two antennas (P < .05). Ablations were generally smaller in vivo compared with ex vivo. CONCLUSION The use of multiple antennas and simultaneous power delivery creates larger, more confluent ablations with greater temperatures than those created with sequential power delivery.

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.

Diagnostic Radiology Resident Compliance with Recommended Health Guidelines : Effect of Resident Work Environment

RATIONALE AND OBJECTIVES To determine diagnostic radiology resident compliance with recommended health guidelines for physical activity, body weight, diet, related health indicators, and the effects of the resident work environment on compliance. MATERIALS AND METHODS A request was electronically mailed to members of the Association of Program Directors in Radiology and the Association of Program Coordinators in Radiology in May 2007 and again in June 2007, asking members to forward to their radiology residents an invitation to complete an online health survey. Frequency counts and Fishers exact test, respectively, were used to summarize results and to determine statistically significant relationships between survey variables. RESULTS A total of 811 radiology residents completed the survey, representing 18% of 4,412 diagnostic radiology residents. Five hundred forty-five (67.2%) of 811 were male and 264 (32.6%) female. Two hundred ten (25.9%) were first-year, 239 (29.5%) second-year, 201 (24.8%) third-year, and 161 (19.9%) fourth-year residents. Three hundred two (37.2%) engaged in recommended guidelines for physical activity and < or =465 (57.3%) complied with each of multiple federal dietary guidelines (excluding alcohol intake). Up to 329 (40.6%) residents did not know whether they were in compliance with various dietary guidelines. A total of 426 (52.5%) residents reported working > or =60 hours/week, which significantly correlated with less physical activity (P = .013). CONCLUSION A substantial number of residents are out of compliance with federal guidelines for physical activity and diet and are not knowledgeable about their personal dietary intake. Long work hours are related to a lack of physical activity. Radiology programs may be able to influence resident health practices by modifying work hours and the working environment, encouraging healthy dietary intake and physical activity, and instituting campaigns to inform residents and faculty about health guidelines and available wellness programs.

Monitoring microwave ablation for liver tumors with electrode displacement strain imaging

Minimally invasive ablative therapies have become important alternatives to surgical treatment of both hepatocellular carcinoma (HCC) and liver metastases. Image based guidance and monitoring are therefore essential. Although ultrasound (US) imaging suffers from inadequate echogenic contrast between ablated and normal tissue, US based elasticity imaging has shown remarkable ability to depict ablated regions and delineate margins. The purpose of this study is to apply “electrode displacement elastography,” or EDE for monitoring clinical microwave ablation (MWA) treatments for HCC and liver metastases. EDE images were acquired from 10 patients who underwent MWA for their liver tumors. The MWA system used was a Neuwave Medical Certus 140 (Madison, WI, USA) operating at 2.45 GHz. The MWA power and duration was adjusted for each patient, with typical values of 65 watts and 5 minutes. A Siemens S2000 scanner equipped with a curvilinear array transducer (VFX 6C1) pulsed at 4 MHz was used to acquire radiofrequency echo data. Electrode displacement was applied manually by the physician. A multi-seed two-dimensional tracking algorithm, with kernel dimensions of 0.096 mm × 3 A-lines was used to estimate local displacements between consecutive data frames. Strain images were computed as the gradient of the local displacement estimates. The average contrast of the ablated region was 0.23±0.07 (0.14-0.35) on B-mode images and 0.73±0.08 (0.56-0.82) on EDE. The average contrast improvement with EDE over B mode was about 230%. The average tumor size was 2.2±0.8 (0.7-3.5) cm on pre-treatment diagnostic images (CT or MRI). The average size of the ablated region was 3.8±0.7 (2.6-4.9) cm on EDE, with an average ablation margin of 1.6 cm which is within the clinically suggested ablated margin (>0.5 cm).

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.

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.

Thrombocytosis is Predictive of Postoperative Pulmonary Embolism in Patients With Gynecologic Cancer.

Objectives The prompt diagnosis of postoperative pulmonary embolism (PE) in gynecologic oncology patients is imperative, but the clinical presentation is nonspecific in this high-risk group. We sought to determine risk factors and clinical findings that may assist clinicians in diagnosing PE in the inpatient setting. Methods Radiology data were queried to identify patients with gynecologic cancer who had a postoperative PE evaluation with computed tomography pulmonary angiography (CT-PA). Patient clinical findings at the time of the PE evaluation were abstracted, and univariate and multivariate regression analyses were performed to identify predictors of PE. Results For 6 years, there were 2498 major gynecologic oncology surgical procedures performed at our institution. Within 14 days of surgery, 107 CT-PA studies were obtained with a positive study rate of 24.3%. In patients with and without PE, there was no significant difference noted for age, oxygen saturations, body mass index and heart rate. After controlling for stage, history of venous thromboembolism (VTE), heart rate, and oxygen saturation, platelet count (odds ratio, 1.26 per 50 counts increase; 95% confidence interval, 1.07–1.48; P = 0.006) and history of VTE (odds ratio, 17.1; 95% confidence interval, 1.77–Inf, P = 0.014) were identified as independent predictors of PE in the multivariate model. Conclusions Although clinicians often use tachycardia and low oxygen saturation as triggers to order PE imaging studies, these signs have a very low specificity. Given the findings of our study, accounting for high platelet count and history of VTE increases the pretest probability of CT-PA study.

A new diagnostic test for endometrial cancer?: Cytology analysis of sonohysterography distention media.

Objective During saline-infused sonohysterography (SIS), the distension fluid is typically discarded. If cytology analysis could identify those patients with endometrial cancer, many women would be spared from further procedures. Methods Thirty consecutive patients with clinical stage I or II endometrial adenocarcinoma were prospectively recruited preoperatively. Saline-infused sonohysterography was performed by instilling 5 mL of saline, withdrawing and sending for analysis. Saline was reinfused until complete SIS images were obtained and sent separately for cytology. Results Of the 30 women enrolled, SIS was technically successful in 29. Demographics included mean age (60.5 ± 6.99 years), body mass index (35.55 ± 8.18 kg/m2), endometrioid histology (76%), and grade (grade 1, 67%). Prestudy diagnostic method included biopsy (70%), dilatation and curettage (17%), and hysteroscopy (10%). Adequate cytology specimens were obtained in 66% of the 5 mL flushes and 72% of the complete SIS collections. Of adequate specimens, the sensitivities to detect endometrial cancer for the 5-mL, complete, and combined fluid samples were 26% (95% confidence interval, 9%–51%), 36% (17%–59%), and 42% (22%–63%). Sensitivity based on the whole study sample (N = 30) was 33% (17%–53%). Statistical significance was not found in the association between a positive test and age, body mass index, grade, diagnostic method, or volume instilled or aspirated. Conclusions Most patients with early endometrial cancer can undergo SIS procedures with adequate cytology specimens obtained from distention media. However, the sensitivity is low, and refinements are necessary before utilizing as a diagnostic test. In cases with positive results, the patient may be able to avoid other costly and painful procedures.