Coronary computed tomography angiography at 140 kV versus 120 kV: assessment of image quality and radiation exposure in overweight and moderately obese patients.

BACKGROUND: Although a tube potential of 140 kV is available on most computed tomography (CT) scanners, its incremental diagnostic value versus 120 kV has been controversial. PURPOSE: To retrospectively evaluate the image quality and radiation exposure of cardiac computed tomography angiography (CCTA) performed at 140 kV in comparison to CCTA at 120 kV in overweight and moderately obese patients. MATERIAL AND METHODS: Eighty-eight patients who were referred for CCTA between January 2010 and May 2012 were included. Forty-four patients who were overweight or moderately obese (body mass index [BMI], 25-35 kg/m(2)) underwent CCTA with dual-source CT (DSCT) scanner at 140 kV. Forty-four match controls who underwent CCTA with DSCT at 120 kV were identified per BMI, average heart rate, scan indication, and scan acquisition mode. All scans were performed per routine protocols with direct physician supervision. Quantitative image metrics (CT attenuation, image noise, contrast-to-noise ratio [CNR], and signal-to-noise ratio [SNR] of left main [LM] and proximal right coronary artery [RCA]) were assessed. Effective radiation dose was compared between the two groups. RESULTS: Overall, all scans were diagnostic without any non-evaluable coronary segment per clinical report. 140 kV had a lower attenuation and image noise versus 120 kV (P<0.01). Both SNR and CNR of proximal coronary arteries were similar between 140 kV and 120 kV (SNR, LM P=0.93, RCA P=0.62; CNR, LM P=0.57, RCA P=0.77). 140 kV was associated with a 35.3% increase in effective radiation dose as compared with 120 kV (5.1 [3.6-8.2] vs. 3.3 [2.0-5.1] mSv, respectively; P<0.01). CONCLUSION: 140 kV CCTA resulted in similar image quality but a higher effective radiation dose in comparison to 120 kV CCTA. Therefore, in overweight and moderately obese patients, a tube potential of 120 kV may be sufficient for CCTA with diagnostic image quality.

Comparison of percutaneous and surgical approaches to renal tumor ablation: metaanalysis of effectiveness and complication rates.

PURPOSE: To determine the effectiveness and complication rates of ablation of renal cell carcinoma (RCC) performed with a percutaneous approach versus a surgical approach. MATERIALS AND METHODS: A search performed on PubMed identified series of renal tumor ablations. Keywords searched included "radiofrequency" (RF), "cryoablation", "cryosurgery", "cryotherapy", "ablation", "renal", "kidney", and "RCC". Review articles were excluded from the search of English-language literature from January 1996 through August 2006. Inclusion criteria were (i) more than one case, (ii) use of RF ablation or cryoablation, (iii) effectiveness based on follow-up imaging, and (iv) report of complication rate. Effectiveness was defined by the proportion of tumors without residual enhancement after one treatment session (ie, primary effectiveness) or after repeated treatments (ie, secondary effectiveness). Major complications were defined as events with substantial morbidity, disability, or increasing level of care. Metaanalysis was performed on primary effectiveness, secondary effectiveness, and major complication rates with a random-effects model. Differences were considered significant if the 95% CIs did not overlap. RESULTS: Forty-six series (28 percutaneous, 18 surgical) met all inclusion criteria. The primary effectiveness rate for the percutaneous group (87%) was significantly lower than that in the surgical group (94%; P < .05). The secondary effectiveness rate in the percutaneous treatment group (92%) was not significantly different from that in the surgical treatment group (95%; P > .05). The major complication rate in the percutaneous treatment group (3%) was significantly lower than that in the surgical treatment group (7%; P < .05). CONCLUSIONS: Based on a metaanalysis, when ablating renal tumors, a percutaneous approach was safer than an open or laparoscopic approach and was equally effective. However, more than one procedure was needed to treat the tumor completely.

The prevalence of symptomatic and coincidental pulmonary embolism on computed tomography.

PURPOSE: To investigate the proportion of pulmonary embolism (PE) on computed tomographic pulmonary angiography (CTPA) and the proportion of coincidental PE on regular contrast-enhanced CT in oncological and nononcological patients. METHODS: This study received internal review board approval and was Health Insurance Portability and Accountability Act compliant. All consecutive adult patients who had contrast-enhanced chest CT or dedicated CTPA during January 2005 were studied. Procedural codes were used to identify cases, and all CT images were reviewed. Clinical data collected included oncology status, chemotherapy regimen, site of tumor, and location of PE. chi2 Tests were used for statistical analysis. RESULTS: Two hundred twenty-nine patients had CTPA, and 27 (11.8%) of them were positive for PE. Of 1168 patients who had contrast-enhanced CT for other indications, coincidental PE was found in 21 patients (1.8%). The proportions of coincidental PE were 3.3% of patients with progressive cancer, 2.5% of patients with stable cancer, 0.7% of patients with no evidence of cancer posttreatment, and 1.0% of nononcological patients. Coincidental PE was found more frequently in patients with progressive cancer compared with nononcological patients (P = 0.035). Patients who were on chemotherapy also had a higher risk of coincidental PE (P=0.019). CONCLUSIONS: The prevalence of symptomatic PE on dedicated CTPA was 11.8%, and the rate of coincidental PE on contrast-enhanced CT was 1.8%. Coincidental PE was significantly higher inpatients with progressive cancer or those receiving chemotherapy.

Feasibility of aortic valve assessment with low dose prospectively triggered adaptive systolic (PTAS) cardiac computed tomography angiography.

BACKGROUND: Cardiac computed tomography angiography (CTA) is feasible for aortic valve evaluation, but retrospective gated protocols required high radiation doses for aortic valve assessment. A prospectively triggered adaptive systolic (PTAS) cardiac CT protocol was recently described in arrhythmia using second-generation dual-source CT. In this study, we sought to evaluate the feasibility of PTAS CTA to assess the aortic valve at a low radiation dose. FINDINGS: A retrospective cohort of 29 consecutive patients whom underwent PTAS protocols for clinical indications other than aortic valve assessment and whom also received echocardiography within 2 months of CT, was identified. Images were reviewed for aortic valve morphology (tricuspid/bicuspid/prosthetic) and stenosis (AS) by experienced blinded readers. Accuracy versus echocardiography and radiation doses were assessed. CONCLUSIONS: PTAS CTA protocols using second-generation dual-source CT for aortic valve evaluation are feasible at low doses. This protocol should be investigated further in larger cohorts.

Gas distribution in intraabdominal and pelvic abscesses on CT is associated with drainability.

OBJECTIVE: Intraabdominal and pelvic abscesses are treated by percutaneous image-guided drainage, under sedation or general anesthesia. This study attempts to determine if the CT features of gas distribution are associated with "drainability." Our premise was that gas may be trapped deep in a collection as bubbles, if the material is thick. Gas may rise to the surface if the material is thin, forming either an air-fluid level or superficial bubbles. MATERIALS AND METHODS: Patients with intraabdominal and pelvic abscesses were identified by the interventional radiology database, after research ethics board approval. Patients without prior CT were excluded. The imaging and clinical records were analyzed retrospectively. Intracollection gas distribution was recorded as superficial bubbles, deep bubbles, or air-fluid levels. Collections were classified accordingly: type 1, air-fluid levels; type 2, superficial or deep bubbles and air-fluid levels; type 3, superficial bubbles; type 4, deep bubbles; and type 5, no gas. RESULTS: One hundred five abscesses were examined in 61 patients, ranging in age from 2-17 years. Eight of 8 of type 1, 16 of 16 of type 2, 19 of 21 of type 3, 8 of 13 of type 4, and 43 of 47 of type 5 were drainable. The abscesses of all patients with an air-fluid level were drainable. Of abscesses with deep bubbles, 61.5% were drainable, versus 90.5% of those with superficial bubbles. Of those with superficial gas (superficial bubbles or air-fluid levels), 95.6% were drainable. In comparison with superficial gas, abscesses with deep trapped gas were associated with a longer duration of drainage, longer hospital stay, lower percentage of successful drainage, and higher percentage of residual collections. The difference is significant for drainability (p = 0.0048; p = 0.0331 after statistical adjustment for multiple testing). CONCLUSION: Distribution of gas in an intraabdominal or pelvic abscess is associated with drainability. Abscesses with superficial gas (superficial bubbles or air-fluid levels) have a greater chance of being drained successfully than do abscesses with deep trapped gas.