CT-Guided Percutaneous Drilling of Osteoid Osteoma: A Safe, Minimally Invasive and Cost-Effective Method.

BACKGROUND: CT-guided percutaneous drill resection (PDR) for osteoid osteoma fell out of vogue with the advent of radiofrequency ablation (RFA). However, the routine use of RFA is offset by its high cost and need for specialized instrumentation. AIMS AND OBJECTIVES: This study is an analysis of our series of patients treated with PDR, to know its efficacy, safety and cost-effectiveness. MATERIALS AND METHODS: This study is a retrospective analysis of prospectively collected data of 33 patients with a mean age of 10.03 years (2-21 years 13:10 M:F). The proximal femur was the commonest location, followed by shaft femur, tibial shaft, pubic ramus and lateral humeral condyle. Three were recurrences. The procedures were performed by one of four fellowship-trained paediatric orthopaedic surgeons, using a standard protocol with the help of a radiologist. CT-guided drilling was performed under sedation/short general anaesthesia using a guidewire for identification, followed by sequential drilling using a 6.5 mm cannulated drill or a triple ream drill. Patients were hospitalized overnight for pain relief and allowed protected weight bearing as per pain tolerance. They were evaluated weekly for 2 weeks and 3 monthly thereafter. RESULTS: The mean final follow-up was 19.72 months (6 months to 58 months). All patients had complete resolution of symptoms within 3 days of the procedure. There were no major complications and there were two minor complications (haematoma and cutaneous hypoaesthesia). There were no recurrences till the last follow-up. CONCLUSION: This study, one of the first and largest from India about CT-guided PDR, shows that this method can still be safely and effectively used as a primary treatment modality in OO, especially in economically challenged population. It is much more cost-effective than RFA, can be used even for recurrent tumours and can be safely be performed by a general orthopaedic surgeon without any special instrumentation.

Comparing the diagnostic accuracy of contrast-enhanced computed tomographic angiography and gadolinium-enhanced magnetic resonance angiography for the assessment of hemodynamically significant transplant renal artery stenosis.

To compare diagnostic accuracy of contrast-enhanced computed tomographic angiography (CTA) and gadolinium-enhanced magnetic resonance angiography (MRA) for the assessment of hemodynamically significant transplant renal artery stenosis (TRAS). After institutional review board approval, records of 27 patients with TRAS confirmed on digital subtraction angiography (DSA) were retrospectively reviewed. A total of 13 patients had MRA and 14 had CTA before DSA. Two board-certified fellowship-trained radiologists, one each from interventional radiology and body imaging blindly reviewed the DSA and CTA or MRA data, respectively. Sensitivity (SN), specificity (SP), positive predictive value, and negative predictive value of MRA and CTA were estimated using 50% stenosis as the detection threshold for significant TRAS. These parameters were compared between modalities using the Fisher exact test. Bias between MRA or CTA imaging and DSA was tested using the Wilcoxon signed-rank test. Two patients were excluded from the MRA group owing to susceptibility artifacts obscuring the TRAS. The correlation between MRA and DSA measurements of stenosis was r = 0.57 (95% CI:-0.02, 0.87; P = 0.052) and between CTA and DSA measurements was r = 0.63 (95% CI: 0.14, 0.87; P = 0.015); the difference between the 2 techniques was not significant (P = 0.7). Both imaging modalities tended to underestimate the degree of stenosis when compared with DSA. MRA group (SN and SP: 56% and 100%, respectively) and CTA group (SN and SP: 81% and 67%, respectively). There were no significant differences in detection performance between modalities (P>0.3 for all measures). We did not find that either modality had any advantage over the other in terms of measuring or detecting significant stenosis. Accordingly, MRA may be preferred over CTA after positive color Doppler ultrasound screening when not contraindicated owing to lack of ionizing radiation or nephrotoxic iodinated contrast. However, susceptibility of artifacts owing to surgical clips at the anastomosis may limit diagnostic utility of MRA as found in 2 of 13 patients. Trend towards no significant difference between the CTA and enhanced MRA in the detection of hemodynamically significant TRAS.

Imaging of orthotopic liver transplantation: self-assessment module.

The educational objectives for this self-assessment module are for the participant to exercise, self-assess, and improve his or her understanding of imaging of orthotopic liver transplant recipients and to improve familiarity with the complications of orthotopic liver transplantation.

Doppler vibrometry: assessment of arterial stenosis by using perivascular tissue vibrations without lumen visualization.

PURPOSE: To correlate vibration frequency and duration at Doppler vibrometry with stenosis severity determined at catheter angiography. MATERIALS AND METHODS: Sixteen patients (eight women) scheduled to undergo abdominal or pelvic angiography were recruited after providing informed consent. An ultrasonography (US) scanner was customized to acquire raw echo data before conventional Doppler processing. Data were acquired from perivascular tissue regions proximal to stenoses, close to the most narrow lumen, and distal to stenoses in the renal, hepatic, common iliac, and superior mesenteric arteries. The data were processed to quantify vibration frequency and duration. The minimum lumen diameter and the pre- and poststenotic lumen diameters were quantified from angiograms. One patient with a hepatic artery stenosis did not yield measurable vibrometry data due to significant bowel gas. RESULTS: Stenoses (diameter reduction, 43%-91%) were angiographically measured in the six renal arteries, four hepatic arteries, three iliac arteries, and one superior mesenteric artery yielding vibrometry data. Three iliac arteries were normal (<30% diameter reduction at angiography). For these 17 arteries, the vibration frequency was higher with a greater percentage of stenosis [Pearson r = .75; P < .001) and a smaller minimum lumen diameter (r = .72; P < .001). The vibration duration increased with a greater percentage of stenosis (r = .7; P < .001). CONCLUSIONS: Preliminary results indicate that the vibration frequency and duration can be used to quantitatively estimate stenosis severity. Doppler vibrometry is complementary to duplex US and does not require lumen visualization.