Dual-Energy CT–Derived Volumetric Iodine Concentration for the Assessment of Therapeutic Response after Microwave Ablation in a Rabbit Model with Intrahepatic VX2 Tumor

Purpose

To evaluate whether changes in volumetric iodine concentration (VIC) could serve as a suitable predictor of therapeutic response to microwave (MW) ablation in a rabbit intrahepatic VX2 tumor model.

MR Imaging–Based In Vivo Macrophage Imaging to Monitor Immune Response after Radiofrequency Ablation of the Liver

PurposeTo establish molecular magnetic resonance (MR) imaging instruments for in vivo characterization of the immune response to hepatic radiofrequency (RF) ablation using cell-specific immunoprobes.Materials and MethodsSeventy-two C57BL/6 wild-type mice underwent standardized hepatic RF ablation (70 °C for 5 minutes) to generate a coagulation area measuring 6–7 mm in diameter. CD68⁺ macrophage periablational infiltration was characterized with immunohistochemistry 24 hours, 72 hours, 7 days, and 14 days after ablation (n = 24). Twenty-one mice were subjected to a dose-escalation study with either 10, 15, 30, or 60 mg/kg of rhodamine-labeled superparamagnetic iron oxide nanoparticles (SPIONs) or 2.4, 1.2, or 0.6 mg/kg of gadolinium-160 (¹⁶⁰Gd)-labeled CD68 antibody for assessment of the optimal in vivo dose of contrast agent. MR imaging experiments included 9 mice, each receiving 10-mg/kg SPIONs to visualize phagocytes using T2¹-weighted imaging in a horizontal-bore 9.4-T MR imaging scanner, ¹⁶⁰Gd-CD68 for T1-weighted MR imaging of macrophages, or 0.1-mmol/kg intravenous gadoterate (control group). Radiological-pathological correlation included Prussian blue staining, rhodamine immunofluorescence, imaging mass cytometry, and immunohistochemistry.ResultsRF ablation–induced periablational infiltration (206.92 μm ± 12.2) of CD68⁺ macrophages peaked at 7 days after ablation (P < .01) compared with the untreated lobe. T2¹-weighted MR imaging with SPION contrast demonstrated curvilinear T2¹ signal in the transitional zone (TZ) (186 μm ± 16.9), corresponsing to Iron Prussian blue staining. T1-weighted MR imaging with ¹⁶⁰Gd-CD68 antibody showed curvilinear signal in the TZ (164 μm ± 3.6) corresponding to imaging mass cytometry.ConclusionsBoth SPION-enhanced T2¹-weighted and ¹⁶⁰Gd-enhanced T1-weighted MR imaging allow for in vivo monitoring of macrophages after RF ablation, demonstrating the feasibility of this model to investigate local immune responses.     

Evaluation of the In Vivo Efficiency and Safety of Hepatic Radiofrequency Ablation Using a 15-G Octopus? in Pig Liver

Objective

To determine in vivo efficacy of radiofrequency ablation (RFA) in porcine liver by using 15-gauge Octopus® (15-G Octopus®) electrodes to create a large coagulation.

Materials and Methods

A total of 18 coagulations were created by using a 180-W generator and 15-G Octopus® electrodes during laparotomy, performed in 14 pigs. Coagulation necrosis was created in the pig livers by the use of one of three RFA protocols: 1) group A, monopolar RFA using a 15-G Octopus® electrode with a 5-mm inter-electrode distance (n = 4); 2) group B, monopolar RFA using a 15-G Octopus® electrode with a 10-mm inter-electrode distance (n = 6); and 3) group C, switching monopolar RFA using two 15-G Octopus® electrodes (n = 8). The energy efficiency, shape, maximum and minimum diameters (Dmx and Dmi), and the volume of the coagulation volume were measured in each group. The Summary statistics were obtained and Mann-Whitney test was were performed.

Results

The mean ablated volume of each group was 49.23 cm³ in A, 64.11 cm³ in B, and 72.35 cm³ in C. The mean Dmx and Dmi values were 5.68 cm and 4.58 cm in A and 5.97 cm and 4.97 cm in B, respectively. In group C, the mean diameters of Dmx and Dmi were 6.80 cm and 5.11 cm, respectively. The mean ratios of Dmi/Dmx were 1.25, 1.20, and 1.35 in groups A, B, and C, respectively. There was one animal death during the RFA procedure, the cause of which could not be subsequently determined. However, there were no other significant, procedure-related complications during the seven-hour-delayed CT scans.

Conclusion

RFA procedures using 15-G Octopus® electrodes are useful and safe for creating a large ablation in a single electrode model as well as in the multiple electrodes model.     

Assessment of breast cancer response to neoadjuvant chemotherapy: is volumetric MRI a reliable tool?

The purpose of this study was to evaluate the reliability of volumetric magnetic resonance imaging (MRI) in breast cancer size assessment before, during and after neoadjuvant chemotherapy (NAC).Volumetric MRI measures performed on 15 patients with breast cancer were compared with volumes reckoned upon mean lesional diameters, using the same MRI data. Concordance correlation coefficient (CCC), Bland & Altman plots, RECIST evaluation and Cohen's Kappa were assessed, to evaluate the agreement between the two methods.CCC was computed before (0.9357), during (0.8053) and after (0.7499) NAC, in all examinations pooled together (0.8617), and on final tumor volume as a percentage of baseline volume (0.9224). In 2/15 (13.3%) cases RECIST assessment was different. Cohen's Kappa was 0.787 (CI_95% = 0.513-1.062).In summary, volumetric MRI is a reliable tool to assess breast cancer size before, during and after NAC. Further investigations are needed to understand whether improvements in surgical planning are feasible.     

Radiofrequency Ablation of T1a Renal Cell Carcinomas within Renal Transplant Allografts: Oncologic Outcomes and Graft Viability

Purpose

To evaluate oncologic outcomes and graft viability after percutaneous radiofrequency (RF) ablation of renal cell carcinoma (RCC) developing within renal transplant allografts.

CT–Guided Microwave Ablation of 45 Renal Tumors: Analysis of Procedure Complexity Utilizing a Percutaneous Renal Ablation Complexity Scoring System

Purpose

To develop a scoring system that stratifies complexity of percutaneous ablation of renal tumors.

Percutaneous Ablation of a Mesenteric Cyst Using Ethanol: Is It Feasible?

A huge mesenteric cyst in a 61-year-old female was treated by percutaneous ablation using ethanol. Marked shrinkage was achieved and regrowth was not seen 16 months after ablation. Resection is the standard therapy for mesenteric cysts, but it may be valuable to discuss the feasibility of percutaneous ablation before resection if the lesion wall is smooth and thin, and if solid nodules are not depicted on imaging.     

Long-Term Outcome of a Hepatocellular Carcinoma 7½ Years After Surgery and Repeated Radiofrequency Ablation: Case Report and Review of the Literature

An interesting case is presented of a 78-year-old patient with cirrhosis who was managed with combined treatment (surgery and radiofrequency (RF) ablation) for hepatocellular carcinoma (HCC) and has survived for 7(1/2) years. Elevation of the alpha-FP (alpha-fetoprotein) levels was noted 2 years after surgery. CT demonstrated two lesions: one central at the remaining right liver lobe, and the other at the excision site. Biopsy of the lesions confirmed the diagnosis of HCC for both of them. RF ablation of these two lesions was performed in one session with technical success. Four and a half years after the first RF ablation a new recurrence was demonstrated at the CT follow-up control. RF ablation was again applied successfully. The imaging findings and the therapeutic percutaneous management of this patient along with the natural course of HCC and its recurrence are discussed, and the literature concerning risk factors is reviewed.     

Clinically suspected pulmonary embolism: is it safe to withhold anticoagulation after a negative spiral CT?

The goal of this study was 3-month clinical outcome in non-anticoagulated patients with clinically suspected acute pulmonary embolism (PE) following a negative spiral CT. During a 6-month period 305 patients underwent spiral CT, of whom only 8 also had a lung scintigraphy. In patients with a final CT report read as not positive for acute PE, all hospital records and answers to a patient questionnaire were analyzed for episodes of venous thrombembolism (VTE). Acute PE was diagnosed at spiral CT in 61 patients (20 %). Twenty-six of the remaining 244 patients were excluded from further analysis because of (a) long-term anticoagulation due to symptomatic acute deep venous thrombosis (n = 5), clinically diagnosed acute PE (n = 2), chronic recurrent VTE (n = 4), and cardiac disorders (n = 5); and (b) a normal perfusion scintigram (n = 4) or a negative pulmonary arteriogram (n = 6). Three patients were lost to follow-up. Among the remaining 215 patients only 10 had undergone a negative lower extremity venous study. Sixteen patients (7 %) died during the follow-up period, 6 of whom underwent autopsy. Venous thrombembolism was diagnosed in three of the 215 patients (1.4 %, 95 % confidence limits: 0.5–4.0 %), one causing the patient's death. Two patients had advanced thoracic malignancies and the third severe chronic obstructive pulmonary disease (84 years old). A negative spiral CT may be able to exclude clinically significant acute PE with the same accuracy as a normal lung scintigraphy or a negative pulmonary arteriography. Received: 8 February 2000 Revised: 18 May 2000 Accepted: 22 May 2000     

Endovascular management of visceral artery aneurysms: When to watch,when to intervene?

Visceral artery aneurysms (VAA) include splanchnic and renal artery aneurysms. They represent a rare clinical entity, although their detection is rising due to an increased use of cross-sectional imaging. Rupture is the most devastating complication, and is associated with a high morbidity and mortality. In addition, increased percutaneous endovascular interventions have raised the incidence of iatrogenic visceral artery pseudoaneurysms (VAPAs). For this reason, elective repair is preferable in the appropriately chosen patient. Controversy still exists regarding their treatment. Over the past decade, there has been steady increase in the utilization of minimally invasive, non-operative interventions, for vascular aneurysmal disease. All VAAs and VAPAs can technically be fixed by endovascular techniques but that does not mean they should. These catheter-based techniques constitute an excellent approach in the elective setting. However, in the emergent setting it may carry a higher morbidity and mortality. The decision for intervention has to take into account the size and the natural history of the lesion, the risk of rupture, which is high during pregnancy, and the relative risk of surgical or radiological intervention. For splanchnic artery aneurysms, we should recognize that we are not, in reality, well informed about their natural history. For most asymptomatic aneurysms, expectant treatment is acceptable. For large, symptomatic or aneurysms with a high risk of rupture, endovascular treatment has become the first-line therapy. Treatment of VAPAs is always mandatory because of the high risk of rupture. We present our point of view on interventional radiology in the splanchnic arteries, focusing on what has been achieved and the remaining challenges.