Percutaneous Radiofrequency Thermal Ablation of Lung VX2 Tumors in a Rabbit Model: Evaluation with Helical CT Findings for the Complete and Partal Ablation

PURPOSE: To evaluate the radiologic findings for complete and partial ablation after percutaneous CT-guided transthoracic radiofrequency ablation (RFA) of lung VX2 tumor implanted in rabbits. MATERIALS AND METHODS: Thirteen rabbits with successfully implanted lung VX2 were used. Three rabbits as controls did not receive RFA while the other ten rabbits underwent RFA; 5 complete and 5 partial. RFA was performed using an internally cooled, 17-gauge electrode (Radionics, Burlington, MA) with a 1-cm active tip under CT guidance. Postprocedural CT was performed within 3 days, and we analyzed the ablated size, enhancement pattern, shape, margin, and complications of the complete and partial ablation groups. Rabbits were sacrificed after postprocedural CT with an overdose of ketamine, and pathologic findings of the ablated groups were compared with those of the control group. RESULTS: The size of the ablated lesions and the enhancement pattern differed between the completely and partially ablated groups on chest CT. The size of the ablated lesions was increased by 47.1% in the completely ablated group and by 2.1% in the partially ablated group. In the completely ablated group, VX2 tumor showed absolutely no enhancement, whereas only ablated pulmonary parenchyma outside VX2 showed mild enhancement on enhanced CT. In the partial ablated group, a part of VX2 became strongly enhanced on enhanced CT. On microscopic examination, the completely ablated group demonstrated that a viable tumor cell was not visible. In the partially ablated group, however, a viable tumor cell within the surrounding fibrous capsule on the peripheral area of the VX2 was observed. CONCLUSION: The important CT findings for evaluation of complete and partial RFA are the ablated size and enhancement pattern of the ablated lesion.

Usefulness of CT-Guided Automatic Needle Biopsy of Solitary Pulmonary Nodule Smaller than 15 mm

PURPOSE: To evaluate the usefulness of the CT-guided percutaneous lung biopsy for the solitary pulmonary nodules smaller than 15 mm in diameter. MATERIALS AND METHODS: Between April 2002 and May 2003, we evaluated twenty-five patients (11 men, 14 women, mean ages: 52.5 years) who had solitary pulmonary nodules, which we could not discriminate as being benign or malignant on the CT findings. All the subjects had CT-guided percutaenous cutting needle biopsy (PCNB) performed on them at our institution. A definitive diagnosis of benignity or malignancy was established to retrospectively analyze the patient's records. We evaluated the accuracy, sensitivity, specificity and complications of PCNB for the definitive diagnosis of benignity or malignancy. The sensitivity and specificity of PCNB were determined using the Chi-square test, and the correlations with pneumothorax and emphysema after biopsy were analyzed using Spearman's rank correlation coefficient. RESULTS: In two nodules of the twenty-five nodules, no definitive diagnosis could be established. Of the remaining twenty-three nodules, 7 (30.4%) were malignant and 16 (69.6%) were benign. Twenty (87%) of the twenty-three definitively diagnosed nodules were correctly diagnosed with PCNB. Of the twenty nodules, 6 (30%) were malignant and 14 (70%) were benign. The sensitivity and specificity of the malignant nodules were 85.7% (6/7) and 100% (16/16), respectively. The sensitivity and specificity of the benign nodules were 87.5% (14/16) and 85.7% (6/7), respectively. Post-biopsy complication occurred in nine patients (36%): Hemoptysis (n=4, 16%) and pneumothorax (n=5, 20%). However, there was not a statistical significance between pneumothorax and emphysema after biopsy (r=0.3, p=0.15). CONCLUSION: When CT-guided percutaneous lung biopsy of the solitary pulmonary nodules smaller than 15 mm in diameter was performed without an on-site cytopathologist, we know that PCNB can yield high diagnostic accuracy and very few complications.

Functional MRI of Motor Speech Area Combined with Motor Stimulation during Resting Period

PURPOSE: To evaluate functional MR imaging of the motor speech area with and without motor stimulation duringthe rest period. MATERIALS AND METHODS: Nine healthy, right-handed volunteers(M:F=7:2, age:21-40years) wereincluded in this study. Brain activity was mapped using a multislice, gradient echo single shot EPI on a 1.5T MRscanner. The paradigm consisted on a series of alternating rest and activation tasks, performed six times. Each volunteer in the first study(group A) was given examples of motor stimulation during the rest period, while eachin the second study(group B) was not given examples of a rest period. Motor stimulation in group A was achieved bycontinuously flexing five fingers of the right hand. In both groups, maximum internal word generation was achievedduring the activation period. Using fMRI analysis software(Stimulate 5.0) and a cross-correlationmethod(background threshold, 200; correlation threshold, 0.3; ceiling, 1.0; floor, 0.3; minimal count, 3),functional images were analysed. After correlating the activated foci and a time-signal intensity curve, theactivated brain cortex and number of pixels were analysed and compared between the two tasks. The t-test was usedfor statistical analysis. RESULT: In all nine subjects in group A and B, activation was observed in and adjacentto the left Broca's area. The mean number of activated pixels was 31.6 in group A and 27.8 in group B, adifference which was not statistically significant(P>0.1). Activities in and adjacent to the right Broca 's areawere seen in seven of group A and four of group B. The mean number of activated pixels was 14.9 in group A and 18in group B. Eight of nine volunteers in group A showed activity in the left primary motor area with negativecorrelation to the time-signal intensity curve. The mean number of activated pixels for this group was 17.5. Inthree volonteers, activation in the right primary motor area was also observed, the mean number of activatedpixels in these cases was 10.0. CONCLUSION: During the rest period, functional MR imaging of the motor speechcenter combined with motor stimulation was more effective than that without stimulation, and simultaneouslyprovided mapping of the primary motor area.

Experimental Study on the Appropriate Embolic Site During Superior Mesenteric Artery Embolization: Using Coiland Gelfoam

PURPOSE: To determine the effective embolic material and appropriate embolic site by comparing bowel changesafter arterial embolization in dogs in which the proximal or distal level of the superior mesenteric artery hadbeen occluded with gelfoam particles or a coil. MATERIAL AND METHODS: Using the coaxial catheter system,superselective arterial embolization was performed at sixteen sites in four dogs. In groups A and B, each site wasoccluded at the proximal or distal marginal artery, respectively, with gelfoam particles and in groups C and D, atthe proximal or distal artery, respectively, with a coi. All dogs were sacrifed one day after the procedure, andgross and microscopic histologic findings were evaluated. RESULT: In all dogs, the procedure was successful. Ingroup B, significant mucosal destruction, lymphocyte proliferation in submucosa and mucosa, and diffuse swellingin all layers of the intestine were found at all sites. The vessel in the submucosal layer was completelyobstructed by red blood cells and gelfoam.At three sites, the intestine showed diffuse ischemic change, and at oneother site, focal ischemic change was observed. In group D, exudation with destruction of mucosa and submucosalhemorrhage occurred at one site, but in groups A and C, intestinal layers were found to be normal. CONCLUSION: Using a coil, superselective arterial embolization was successful, even up to the distal level of the intestinalartery, and the intestine showed no ischemic change. Embolization with gelfoam must be performed carefully at theproximal level, and since it can cause severe intestinal necrosis, must be avoided at the distal level.

Fluoroscopically Guided Automated Gun Biopsy of Chest Lesions: Diagnostic Accuracy and Complications

PURPOSE: To determine the diagnostic accuracy and frequency of complications of fluoroscopy-guidedtransthoracic needle biopsy, using an automated gun biopsy system. MATERIALS AND METHODS: We retrospectively reviewed 86 patients who underwent automated gun biopsy between October 1995 and October 1996. An 18-gauge cutting needle was used in all cases. All biopsies were performed under fluoroscopic guidance by one interventional radiologist. RESULTS: Tissue sufficient for histologic diagnosis was obtained in 73 of 86 biopsies(84.9%). Fifty-six lesions were malignent and 30 were benign. Sensitivity and diagnostic accuracy for malignant lesions were 87.5% and 87.5%, respectively while cell type specificity in malignant diagnosis was 91.7%(11/12). Sensitivity and diagnostic accuracy for benign lesions were 80.0% and 73.3%, respectively. Postbioptic pneumothorax occurred in three of 86 biopsies(3.5%), one of which required placement of a chest tube. CONCLUSION: Automated gun biopsy is a simple, safe method for the diagnosis of focal chest lesions. An automated biopsy device offers high diagnostic accuracy in cases involving malignant and benign lesions of the chest, and is particularly useful for determining malignant cell type and specific diagnosis of benign lesions.