Combination Therapies: Quantifying the Effects of Transarterial Embolization on Microwave Ablation Zones.

PURPOSE: To quantify the effect of transarterial embolization on microwave (MW) ablations in an in vivo porcine liver model. MATERIALS AND METHODS: Hepatic arteriography and cone-beam computed tomography (CT) scans were performed in 6 female domestic swine. Two lobes were embolized to an endpoint of substasis with 100-300-µm microspheres. MW ablations (65 W, 5 min) were created in embolized (n = 15) and nonembolized (n = 12) liver by using a 2.45-GHz system and single antenna. Cone-beam CT scans were obtained to monitor the ablations, document gas formation, and characterize arterial flow. Ablation zones were excised and sectioned. A mixed-effects model was used to compare ablation zone diameter, length, area, and circularity. RESULTS: Combined transarterial embolization and MW ablation zones had significantly greater area (mean ± standard deviation, 11.8 cm2 ± 2.5), length (4.8 cm ± 0.5), and diameter (3.1 cm ± 0.6) compared with MW only (7.1 cm2 ± 1.9, 3.7 cm ± 0.6, and 2.4 cm ± 0.3, respectively; P = .0085, P = .0077, and P = .0267, respectively). Ablation zone circularity was similar between groups (P = .9291). The larger size of the combined ablation zones was predominantly the result of an increase in size of the peripheral noncharred zone of coagulation (1.3 cm ± 0.4 vs 0.8 cm ± 0.2; P = .0104). Cone-beam CT scans demonstrated greater gas formation during combined ablations (1.8 cm vs 1.1 cm, respectively). Mean maximum temperatures 1 cm from the MW antennas were 86.6°C and 68.7°C for the combined embolization/ablation and MW-only groups, respectively. CONCLUSIONS: Combining transarterial embolization and MW ablation increased ablation zone diameter and area by approximately 27% and 66%, respectively, in an in vivo non-tumor-bearing porcine liver model. This is largely the result of an increase in the size of the peripheral ablation zone, which is most susceptible to local blood flow.

Complex Inferior Vena Cava Filter Retrieval Complicated by Migration of Filter Fragment into the Aorta and Subsequent Distal Embolization.

In 2005, a 48-year-old man with a spinal cord injury had an inferior vena cava filter placed for recurrent deep vein thrombosis and pulmonary embolism. He was referred for filter retrieval after a computed tomography scan demonstrated caval stenosis and 2 fractured filter arms, 1 in a pulmonary artery and 1 penetrating into the retroperitoneum and impinging on the aorta. During retrieval, 1 arm was inadvertently advanced into the aorta, and embolization of the arm occurred to the left profunda femoris artery. It was subsequently retrieved. This is the first reported case to the authors' knowledge of migration and embolization of a filter fragment into the systemic arterial system.

Percutaneous microwave ablation of hepatic tumors: prospective evaluation of postablation syndrome and postprocedural pain.

PURPOSE: To prospectively investigate the frequency and severity of postablation syndrome (PAS) and postprocedural pain in a cohort of patients undergoing hepatic microwave ablation. MATERIALS AND METHODS: From March 2009 to November 2011, 54 consecutive patients undergoing microwave ablation for liver tumors were enrolled. A questionnaire was administered to investigate PAS and pain at 1, 7, and 40 days after ablation. Four patients did not complete all three questionnaires and were excluded from the analysis. Additionally, laboratory tests with results known to significantly increase or decrease after ablation were performed, and ablation parameters were recorded. Potential predictors of PAS and pain at 1 and 7 days were evaluated by a logistic regression model. RESULTS: Fifty patients underwent a single microwave ablation session, 33 for hepatocellular carcinoma (HCC) and 17 for liver metastasis. Median ablation volumes on computed tomography were 31 cm(3) for HCC and 42 cm(3) for metastasis. Sixty percent of patients experienced PAS in the first week. Aspartate aminotransferase (AST) levels after ablation were significantly associated with PAS during postprocedure days 1-7. Median visual analog scale scores for pain at the puncture site were 1 and 0.24 at 1 and 7 days, respectively. The risk of having at least moderate pain in the first week was significantly related to ablation volume and time and postablation increase in AST level. CONCLUSIONS: The incidence and severity of PAS with hepatic microwave ablation is similar to that reported for radiofrequency ablation, with the best predictive factor being postablation AST level elevation. Postablation pain was best predicted by total ablation volume and AST level.

High-powered gas-cooled microwave ablation: shaft cooling creates an effective stick function without altering the ablation zone.

OBJECTIVE: The purpose of our study was to validate the ability of a new gas-cooled microwave device to secure antennas into tissue before ablation via shaft cooling and to verify that such cooling does not compromise the intended ablation. MATERIALS AND METHODS: The force required to extract several types of applicators from ex vivo bovine liver before and after ablation was measured. Six groups were compared: cooled needle and multitined radiofrequency electrodes, secured and unsecured cryoprobes, and gas-cooled microwave antennas (n = 6 each). Ablations were next created in in vivo porcine livers for 2 and 10 minutes (n = 6 each) using the gas-cooled microwave system at 140 W. Extraction force was again measured before and after ablation and compared between groups using analysis of variance with post hoc Student t tests. Histologic analysis of the ablation zone was performed to evaluate cellular necrosis along the antenna shaft. RESULTS: Ex vivo, the secured cryoprobe and microwave antenna required significantly more force to remove than unsecured radiofrequency, cryoprobe, and microwave applicators (p < 0.05, all comparisons). The multitined radiofrequency electrode and cooled radiofrequency electrode required significantly more force to remove after ablation than before ablation (p = 0.006 and 0.02, respectively). In vivo, the secured antenna required significantly more force to remove before ablation than after ablation at both 2 (p < 0.0001) and 10 minutes (p < 0.0001). There was no histologic evidence of cell preservation along the antenna shaft. CONCLUSION: The gas cooling used in this microwave device can effectively secure antennas into tissue without altering ablation shape or reducing the intended thermal damage.

Mastitis and More: A Pictorial Review of the Red, Swollen, and Painful Breast.

Clinically, acute mastitis presents as a red, swollen, and painful breast. Targeted ultrasound can be performed to evaluate the extent of infection and for an underlying abscess. Noncomplicated mastitis or a small fluid collection may respond to oral antibiotics without further intervention, but a larger or more complex abscess may require single or serial percutaneous aspiration. Breast infections, particularly those complicated by an abscess, can have a prolonged clinical course, and close follow-up is required. Since the clinical presentation and imaging features of acute infectious mastitis can overlap with other etiologies, such as inflammatory breast cancer and idiopathic granulomatous mastitis, a percutaneous biopsy may be indicated to accurately diagnose patients.

Tumor ablation: common modalities and general practices.

Tumor ablation is a minimally invasive technique that is commonly used in the treatment of tumors of the liver, kidney, bone, and lung. During tumor ablation, thermal energy is used to heat or cool tissue to cytotoxic levels (less than -40°C or more than 60°C). An additional technique is being developed that targets the permeability of the cell membrane and is ostensibly nonthermal. Within the classification of tumor ablation, there are several modalities used worldwide: radiofrequency, microwave, laser, high-intensity focused ultrasound, cryoablation, and irreversible electroporation. Each technique, although similar in purpose, has specific and optimal indications. This review serves to discuss general principles and technique, reviews each modality, and discusses modality selection.

Geographic distribution of human blastomycosis cases in Milwaukee, Wisconsin, USA: association with urban watersheds.

Most studies of endemic blastomycosis and outbreaks have involved rural areas. Case homesites in rural Northern Wisconsin have been associated with waterways and sand soils. ARC-GIS was used to geocode addresses and to observe geographic features of homesites from 45 State-mandated reports of human blastomycosis in urban Milwaukee County, Southeastern Wisconsin 2000-2004. Each case property was directly observed, and houses and duplexes (N = 38) were compared with 151 same-street control homesites. Categorical data was analyzed using a chi-square or Fisher's exact test; continuous variables by Kruskal-Wallis test. One case cluster was seen on Milwaukee's North side where the estimated annual incidence was 2.8/100,000 compared to 0.96/100,000 for the entire county. Cases were less common in the most urbanized watersheds (0.49/100,000/yr) versus Lake Michigan shores (0.85) versus remaining three open watersheds (1.4) [P<0.01]. Case homesites averaged 1067 m to waterways and none were on sand soils. (Comparison is made to a Northern Wisconsin community where case homesites averaged 354 m to waterways, 24/25 were on sand soils and annual incidence was 74/100,000.) No unique features of case homesites were identified in Milwaukee County. In this urban area of Wisconsin, relatively low incidence rates may be explained, in part, by lower density of inland waterways and lack of sand soils, however, blastomycosis cases appear to be associated with open watersheds.