Judy Ahrar

Preclinical Assessment of a 980-nm Diode Laser Ablation System in a Large Animal Tumor Model

PURPOSE To characterize the performance of a 980-nm diode laser ablation system in an in vivo tumor model. MATERIALS AND METHODS This study was approved by the institutional animal care and use committee. The ablation system consisted of a 15-W, 980-nm diode laser, flexible diffusing-tipped fiber optic, and 17-gauge internally cooled catheter. Ten immunosuppressed dogs were inoculated subcutaneously with canine-transmissible venereal tumor fragments in eight dorsal locations. Laser ablations were performed at 79 sites where inoculations were successful (99%) at powers of 10 W, 12.5 W, and 15 W, with exposure times between 60 and 180 seconds. In 20 cases, multiple overlapping ablations were performed. After the dogs were euthanized, the tumors were harvested, sectioned along the applicator tract, measured, and photographed. Measurements of ablation zone were performed on gross specimen. Histopathology and viability staining was performed with hematoxylin and eosin and nicotinamide adenine dinucleotide hydrogen staining. RESULTS Gross pathologic examination confirmed a well circumscribed ablation zone with sharp boundaries between thermally ablated tumor in the center surrounded by viable tumor tissue. When a single applicator was used, the greatest ablation diameters ranged from 12 mm at the lowest dose (10 W, 60 seconds) to 26 mm at the highest dose (15 W, 180 seconds). Multiple applicators created ablation zones as large as 42 mm in greatest diameter (with the lasers operating at 15 W for 120 seconds). CONCLUSIONS The new 980-nm diode laser and internally cooled applicator effectively create large ellipsoid thermal ablations in less than 3 minutes.

Hepatic artery chemoembolization in patients with ocular melanoma metastatic to the liver: Response, survival, and prognostic factors

Background:Although hepatic arterial chemoembolization (HACE) has been used for treatment of ocular melanoma metastatic to the liver, the prognostic indicators for survival after HACE have not been studied. We evaluated response rates and survival durations after HACE in such patients and analyzed factors affecting their survival. Methods:The medical records of patients with ocular melanoma metastatic to liver who underwent HACE at our institution from 1992 to 2005 were reviewed. The radiologic tumor response rates, and overall survival (OS) and progression-free survival durations were calculated, and patient, tumor, and treatment variables were analyzed to identify factors influencing survival. Results:One hundred twenty-five patients underwent 265 HACE sessions. Of 105 patients in whom radiologic responses could be evaluated, 12 (11%) had partial responses, 17 (16%) had minor responses, 68 (65%) had stable disease, and 8 (8%) had progressive disease. The median OS and progression-free survival durations were 6.7 and 3.8 months, respectively. Multivariate analysis showed that >75% liver involvement and high lactate dehydrogenase levels were associated with short OS. Patients who had radiologic responses to HACE had a longer median OS duration than did patients who did not (15.8 vs. 6.1 months; P = 0.0005). Patients with >75% liver involvement had a median OS duration of only 2.4 months. Conclusions:HACE resulted in radiologic response or disease stabilization in most patients with ocular melanomas metastatic to the liver. The extent of liver involvement, baseline lactate dehydrogenase levels, and response to therapy were found to be significant predictors of OS after HACE.

Real-time magnetic resonance imaging-guided cryoablation of small renal tumors at 1.5 T

ObjectivesReal-time magnetic resonance imaging (MRI)–guided cryoablation has been investigated in open MRI systems with low magnetic fields (0.2–0.5 T). More advanced imaging techniques and faster imaging rates are possible at higher magnetic fields, which often require a closed-bore magnet design. However, there is very little experience with real-time interventions in closed-bore 1.5-T MRI units. Herein, we report our initial experience with real-time MRI-guided cryoablation of small renal tumors using a prototype balanced steady-state free precession imaging sequence in a closed-bore 1.5-T MRI system. Materials and MethodsFrom August 2008 to April 2012, 18 patients underwent MRI-guided cryoablation of small renal tumors. A 1.5-T cylindrical MRI scanner with a 125 cm × 70 cm bore and a prototype balanced steady-state free precession sequence (BEAT interactive real-time tip tracking) were used to guide the placement of 17-gauge cryoprobes in real time. Ice ball formation was monitored every 3 minutes in 1 or more imaging planes. Each ablation consisted of 2 freeze-thaw cycles. Contrast-enhanced MRI was performed after the second active thaw period. Follow-up consisted of clinical evaluation and renal protocol computed tomography (CT) or MRI performed at 1, 6, 12, 18, and 24 months and annually thereafter. ResultsDuring the study period, we successfully ablated 18 tumors in 18 patients in 18 sessions. The mean tumor size was 2.2 cm (median, 2 cm; range, 1.2–4.4 cm). The number of cryoprobes used per patient was determined based on tumor size. The mean number of cryoprobes used per patient was 3 (median, 3 cryoprobes; range, 2–4 cryoprobes). Fifty-six cryoprobes, 9 biopsy needles, and 2 hydrodissection needles were successfully placed under real-time MRI guidance using BEAT interactive real-time tip tracking sequence. Hydrodissection under MRI guidance was successfully performed in 4 patients. In each patient, contrast-enhanced MRI performed after the second active thaw period revealed a sharply defined avascular zone surrounding the targeted tumor, which confirmed complete ablation of the tumor with adequate margins. Although contrast media slowly accumulated in the targeted tumor in 9 patients immediately after the procedure, follow-up imaging studies performed at a mean of 16.7 months revealed no contrast enhancement within the ablation zone in these patients. Disease-specific, metastasis-free, and local recurrence-free survival rates were all 100%. ConclusionsReal-time placement and manipulation of cryoprobes during MRI-guided cryoablation of small renal tumors in a closed-bore, high–magnetic field scanner are feasible. Technical and clinical success rates are similar to those of patients who undergo CT-guided radiofrequency ablation or cryoablation of small renal tumors. Our findings suggest that MRI-guided ablation has several advantages over CT-guided ablation, including real-time guidance for probe placement, multiplanar imaging, exquisite soft tissue contrast, and lack of ionizing radiation.

Response, survival, and prognostic factors after hepatic arterial chemoembolization in patients with liver metastases from cutaneous melanoma

We reviewed the medical records of 42 patients with cutaneous melanoma metastatic to the liver who underwent hepatic artery chemoembolization (HACE) at our institution. HACE resulted in radiologic response (38.9%) or disease stabilization (47.2%) in most patients. The median overall survival (OS) and time to progression (TTP) of liver disease were 7.7 and 6 months, respectively. Patients age, lactate dehydrogenase (LDH) levels, type of treatment, number of extrahepatic metastatic sites, and response to therapy were found to be significant predictors of OS after HACE. Prolonged survival was seen in patients who responded to HACE (p = .034).

Characterization of Contrast Enhancement in the Ablation Zone Immediately after Radiofrequency Ablation of Renal Tumors

PURPOSE To characterize the degree of contrast enhancement within the ablation zone immediately after radiofrequency (RF) ablation of renal tumors. MATERIALS AND METHODS Patients with renal tumors treated with percutaneous RF ablation at one institution between January 2004 and October 2007 were retrospectively reviewed. For each tumor, computed tomography (CT) density measurements were made at four phases (noncontrast, arterial phase, parenchymal phase, and excretory phase) in each of four CT examinations (before ablation, day 0, 1 month, and 6 months). RESULTS A total of 36 renal tumors in 34 patients were treated with CT-guided RF ablation in 35 sessions. Before RF ablation, all tumors exhibited enhancement after intravenous administration of contrast material. The peak density was reached during the parenchymal phase, with a partial washout of contrast agent in the excretory phase. On CT images acquired immediately after RF ablation (day 0), 28 of the 36 ablated tumors (78%) exhibited clinically significant homogeneous enhancement (ie, density change >10 HU) within the ablation zone. However, contrast-enhanced CT studies performed at 1 and 6 months revealed no clinically significant enhancements in any of the 36 treated tumors (mean density changes of 4 HU at 1 month and 3 HU at 6 months). CONCLUSIONS Contrast-enhanced CT studies revealed a mild, temporary homogenous contrast enhancement of the ablation zone immediately after RF ablation of renal tumors, which should not be mistaken for a residual, unablated tumor. This enhancement in the ablation zone eventually disappears in follow-up contrast-enhanced CT studies.

Magnetic resonance imaging-guided biopsy in the musculoskeletal system using a cylindrical 1.5-T magnetic resonance imaging unit.

Objectives The objective of this study was to report a single-center experience with magnetic resonance imaging (MRI)–guided biopsy in the musculoskeletal system using a closed-bore, cylindrical, high-magnetic-field (1.5-T) MRI unit. Methods From May 2010 to July 2011, 100 consecutive MRI-guided biopsy sessions were undertaken for musculoskeletal lesions in 97 patients. Patient demographics, tumor characteristics, and biopsy techniques were recorded. Biopsy results, treatment outcomes, and follow-up imaging studies were reviewed. Results Biopsy procedures were technically successful in 99 cases (99%). Despite a mean body mass index of 30 kg/m2, all patients fit within the bore of the magnet. There were 69 soft-tissue and 31 bone tumors. Most patients had both tissue core (n = 93) and fine-needle aspiration (n = 84) biopsies. All lesions were adequately imaged, localized, and targeted using rapid balanced steady-state free precession imaging (89%), fast T1 (4%), or combination of the 2 techniques (7%). A prototype real-time imaging sequence was used in 29 cases (29%) to guide biopsy needle insertion. There were no major complications. Sensitivity, specificity, and overall accuracy were 97%, 100%, and 97.6%, respectively. Conclusions Magnetic resonance imaging–guided biopsy in a closed-bore, high-field-strength magnet is a safe, easy, and effective technique for evaluation of musculoskeletal lesions. Ideally, the MRI suite should be equipped with an in-room radiofrequency-shielded monitor and a communication system. However, surface coils with adequate opening to grant access to the biopsy site, MRI-compatible needles, and MRI-compatible patient monitoring devices are absolutely necessary to perform MRI-guided biopsies.

Standardized Reporting in IR: A Prospective Multi-Institutional Pilot Study

PURPOSE To assess adoption and survey-based satisfaction rates following deployment of standardized interventional radiology (IR) procedure reports across multiple institutions. MATERIALS AND METHODS Standardized reporting templates for 5 common interventional procedures (central venous access, inferior vena cava [IVC] filter insertion, IVC filter removal, uterine artery embolization, and vertebral augmentation) were distributed to 20 IR practices in a prospective quality-improvement study. Participating sites edited the reports according to institutional preferences and deployed them for a 1-year pilot study concluding in July 2015. Study compliance was measured by sampling 20 reports of each procedure type at each institution, and surveys of interventionalists and referring physicians were performed. Modifications to the standardized reporting templates at each site were analyzed. RESULTS Ten institutions deployed the standardized reports, with 8 achieving deployment of 3-12 months. The mean report usage rate was 57%. Each site modified the original reports, with 26% mean reduction in length, 18% mean reduction in wordiness, and 60% mean reduction in the number of forced fill-in fields requiring user input. Linear-regression analysis revealed that reduced number of forced fill-in fields correlated significantly with increased usage rate (R2 = 0.444; P = .05). Surveys revealed high satisfaction rates among referring physicians but lower satisfaction rates among interventional radiologists. CONCLUSIONS Standardized report adoption rates increased when reports were simplified by reducing the number of forced fill-in fields. Referring physicians preferred the standardized reports, whereas interventional radiologists preferred standard narrative reports.

Renal Mass Biopsy

Several factors have led to renewed interest in percutaneous renal mass biopsy, including an increase in incidental detection of small renal masses on routine cross-sectional imaging studies, the availability of conservative and minimally invasive treatment options for selected patients with renal cell carcinoma, and advances in molecular targeted therapy for patients with advanced renal cancer. Percutaneous renal mass biopsy is a safe procedure with low complication rates. Previously feared potential complications such as severe hemorrhage and needle tract seeding have not been encountered in the largest contemporary series published. Advances in cross-sectional imaging technologies, including ultrasonography, computed tomography, and magnetic resonance imaging, have enabled greater precision in localizing and targeting renal tumors for biopsy. Fine-needle aspiration or core needle biopsy is performed through a guiding cannula in a coaxial fashion, allowing the operator to obtain multiple tissue samples without reinserting the needle through the entire tract. Core needle biopsy has a diagnostic accuracy of greater than 90 %; thus, percutaneous biopsy can in many instances have a significant impact on the clinical management of a patient with a renal mass.

Ultrasound-Guided Biopsy

In recent years, ultrasonography has become an essential component of most interventional radiology departments. Ultrasonography provides effective and efficient guidance for biopsy procedures. Needle-guidance systems can simplify biopsy procedures for radiologists with limited experience by enabling the radiologist to maintain the needle’s path within the ultrasound beam at all times. In this manner, the needle can be advanced on target with confidence. Experienced interventional radiologists can use the freehand technique that allows greater flexibility with respect to skin puncture and needle path, allowing for creativity in reaching difficult targets. The most important advantage of ultrasonography over computed tomography in image-guided biopsy is the ability to visualize the needle tip at all times during insertion and sampling process. Ultrasonography has limited use in guiding biopsies in obese patients, when lesions are very deep or when highly reflective surfaces (e.g., bone or gas-filled bowel) obscure the view of the lesion. This chapter outlines the equipment, advantages, disadvantages, applications, and techniques used in ultrasound-guided biopsies.

Implications for high-precision dose radiation therapy planning or limited surgical resection after percutaneous computed tomography-guided lung nodule biopsy using a tract sealant

Purpose Precision radiation therapy such as stereotactic body radiation therapy and limited resection are being used more frequently to treat intrathoracic malignancies. Effective local control requires precise radiation target delineation or complete resection. Lung biopsy tracts (LBT) on computed tomography (CT) scans after the use of tract sealants can mimic malignant tract seeding (MTS) and it is unclear whether these LBTs should be included in the calculated tumor volume or resected. This study evaluates the incidence, appearance, evolution, and malignant seeding of LBTs. Methods and materials A total of 406 lung biopsies were performed in oncology patients using a tract sealant over 19 months. Of these patients, 326 had follow-up CT scans and were included in the study group. Four thoracic radiologists retrospectively analyzed the imaging, and a pathologist examined 10 resected LBTs. Results A total of 234 of 326 biopsies (72%, including primary lung cancer [n = 98]; metastases [n = 81]; benign [n = 50]; and nondiagnostic [n = 5]) showed an LBT on CT. LBTs were identified on imaging 0 to 3 months after biopsy. LBTs were typically straight or serpiginous with a thickness of 2 to 5 mm. Most LBTs were unchanged (92%) or decreased (6.3%) over time. An increase in LBT thickness/nodularity that was suspicious for MTS occurred in 4 of 234 biopsies (1.7%). MTS only occurred after biopsy of metastases from extrathoracic malignancies, and none occurred in patients with lung cancer. Conclusions LBTs are common on CT after lung biopsy using a tract sealant. MTS is uncommon and only occurred in patients with extrathoracic malignancies. No MTS was found in patients with primary lung cancer. Accordingly, potential alteration in planned therapy should be considered only in patients with LBTs and extrathoracic malignancies being considered for stereotactic body radiation therapy or wedge resection.