Pathological effects of lung radiofrequency ablation that contribute to pneumothorax, using a porcine model.

OBJECTIVES: The incidence of pneumothorax is 7 times higher after lung radiofrequency ablation (RFA) than after lung biopsy. The reasons for such a difference have never been objectified. The histopathologic changes in lung tissue are well-studied and established for RF in the ablation zone. However, it has not been previously described what the nature of thermal injury might be along the shaft of the RF electrode as it traverses through normal lung tissue to reach the ablation zone. The purpose of this study was to determine the changes occurring around the RF needle along the pathway between the ablated zone and the pleura. MATERIAL AND METHODS: In 3 anaesthetised and ventilated swine, 6 RFA procedures (right and left lungs) were performed using a 14-gauge unipolar multi-tined retractable 3 cm radiofrequency LeVeen probe with a coaxial introducer positioned under CT fluoroscopic guidance. In compliance with literature guidelines, we implemented a gradually increasing thermo-ablation protocol using a RF generator. Helical CT images were acquired pre- and post-RFA procedure to detect and evaluate pneumothorax. Four percutaneous 19-gauge lung biopsies were also performed on the fourth swine under CT guidance. Swine were sacrificed for lung ex vivo examinations, scanning electron microscopy (SEM) and pathological analysis. RESULTS: Three severe (over 50 ml) pneumothorax were detected after RFA. In each one of them, pathological examination revealed a fistulous tract between ablation zone and pleura. No fistulous tract was observed after biopsies. In the 3 cases of severe pneumothorax, the tract was wide open and clearly visible on post procedure CT images and SEM examinations. The RFA tract differed from the needle biopsy tract. The histological changes that are usually found in the ablated zone were observed in the RFA tract's wall and were related to thermal lesions. These modifications caused the creation of a coagulated pulmonary parenchyma rim between the thermo-ablation zone and the pleural space. The structural properties of the damage can explain why the RFA tract is remains patent after needle withdrawal. CONCLUSION: Our study demonstrates for the first time that the changes around the RF needle are the same as in the ablated zone. The damage could create fistulous tracts along the needle path between thermo-ablation zone and pleural space. These fistulas could certainly be responsible for severe pneumothorax that occurs in many patients treated with lung RFA.

Standardized quantitative measurements of wrist cartilage in healthy humans using 3T magnetic resonance imaging.

AIM: To quantify the wrist cartilage cross-sectional area in humans from a 3D magnetic resonance imaging (MRI) dataset and to assess the corresponding reproducibility. METHODS: The study was conducted in 14 healthy volunteers (6 females and 8 males) between 30 and 58 years old and devoid of articular pain. Subjects were asked to lie down in the supine position with the right hand positioned above the pelvic region on top of a home-built rigid platform attached to the scanner bed. The wrist was wrapped with a flexible surface coil. MRI investigations were performed at 3T (Verio-Siemens) using volume interpolated breath hold examination (VIBE) and dual echo steady state (DESS) MRI sequences. Cartilage cross sectional area (CSA) was measured on a slice of interest selected from a 3D dataset of the entire carpus and metacarpal-phalangeal areas on the basis of anatomical criteria using conventional image processing radiology software. Cartilage cross-sectional areas between opposite bones in the carpal region were manually selected and quantified using a thresholding method. RESULTS: Cartilage CSA measurements performed on a selected predefined slice were 292.4 ± 39 mm(2) using the VIBE sequence and slightly lower, 270.4 ± 50.6 mm(2), with the DESS sequence. The inter (14.1%) and intra (2.4%) subject variability was similar for both MRI methods. The coefficients of variation computed for the repeated measurements were also comparable for the VIBE (2.4%) and the DESS (4.8%) sequences. The carpus length averaged over the group was 37.5 ± 2.8 mm with a 7.45% between-subjects coefficient of variation. Of note, wrist cartilage CSA measured with either the VIBE or the DESS sequences was linearly related to the carpal bone length. The variability between subjects was significantly reduced to 8.4% when the CSA was normalized with respect to the carpal bone length. CONCLUSION: The ratio between wrist cartilage CSA and carpal bone length is a highly reproducible standardized measurement which normalizes the natural diversity between individuals.

Usefulness of dynamic contrast-enhanced MRI in the evaluation of the viability of acute scaphoid fracture.

OBJECTIVE: To evaluate the usefulness of dynamic gadolinium-enhanced magnetic resonance imaging (MRI) for assessing the viability of the proximal pole of the scaphoid in patients with acute scaphoid fractures. METHODS: Eighteen consecutive patients with acute scaphoid fracture who underwent dynamic gadolinium-enhanced MRI 7 days or less before surgery were prospectively included between August 2011 and December 2012. All patients underwent MR imaging with unenhanced images, enhanced images, and dynamic enhanced images. A radiologist first classified the MRI results as necrotic or viable based on T1- and T2-weighted images only, followed by a second blinded interpretation, this time including analysis of pre- and post-gadolinium administration images and a third blinded interpretation based on the time-intensity curve of the dynamic enhanced study. The standard of reference was the histologic assessment of a cylindrical specimen of the proximal pole obtained during surgery in all patients. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for unenhanced, enhanced, and dynamic gadolinium-enhanced MRI studies. RESULTS: The sensitivity, specificity, PPV, and NPV were 67, 67, 50, and 80 % for unenhanced images, 83, 100, 100, and 92 for enhanced images, and 83, 92, 83, and 92 for dynamic contrast-enhanced images. CONCLUSIONS: Our data are consistent with previously reported data supporting contrast-enhanced MRI for assessment of viability, and showing that dynamic imaging with time-intensity curve analysis does not provide additional predictive value over standard delayed enhanced imaging for acute scaphoid fracture.

Long-term outcome following laparoscopic adrenalectomy for large solid adrenal cortex tumors.

INTRODUCTION: Laparoscopic adrenalectomy (LA) is the procedure of choice for small benign adrenal tumors. In the absence of local invasion or metastases, the preoperative diagnosis of an adrenocortical carcinoma (ACC) is difficult, often leaving size as the principal predictor of malignancy. Large tumors are resectable laparoscopically, but the long-term outcome and therefore appropriateness of LA for cortical tumors > 6 cm is not known. METHODS: We reviewed the LA experience in our institution since its introduction in June 1994. Patients who underwent LA for solid cortical tumors > or = 60 mm in diameter without preoperative or intraoperative evidence of malignancy were reviewed. Follow-up data, including clinical examination, biochemical analysis, and repeat scans, were reviewed for evidence of local or systemic recurrent disease. RESULTS: Between 1994 and 2004 a total of 462 adrenalectomies were performed, 391 of which were done laparoscopically. Among them, 19 were solid cortical tumors > or = 60 mm in diameter with no overt malignant preoperative or intraoperative characteristics: 9 nonsecreting tumors, 8 Cushing's syndrome tumors (including 2 virilizing variants), 1 virilizing tumor, and 1 aldosteronoma. The mean age of the patients was 49.9 years (range 22-77 years), and the mean tumor size was 69.0 mm (range 60-80 mm). Histology confirmed a cortical adenoma in eight patients, malignant tumors in three, and indeterminate tumors in eight. The mean follow-up was 34 months (range 4-108 months). Two patients died of systemic recurrent disease (liver metastases) at 10 and 19 months, respectively, following surgery; two other patients died 12 and 21 months, respectively following surgery owing to unrelated cardiovascular and cerebrovascular pathology. One patient underwent surgery for local recurrence 54 months after primary surgery; the remaining 14 patients are well with no clinical or radiologic evidence of recurrent disease. CONCLUSIONS: Laparoscopic adrenalectomy for large solid cortical tumors without pre- or intraoperative evidence of malignancy is not contraindicated, and it is unlikely to have a deleterious effect on long-term outcome. Each case should be considered individually. We provide an algorithm for the approach to adrenocortical tumors > or = 6 cm.