Can procedure time for paracentesis be optimized based on bottle selection?

PURPOSE: The purpose of our study was to assess if plastic containers could decrease the overall procedure time for paracentesis relative to more commonly used glass containers. METHODS: In this IRB exempt study, initial pilot data comparing filling time of glass and plastic containers in an ex vivo setting under identical conditions revealed power calculations that n = 37 patients per group would be needed to achieve standard deviation (SD) = 60 s, difference (diff) = 40 s, two-tailed alpha-level 0.05, and power 80%. Total of 43 patients (93 containers) were enrolled and randomized to glass or plastic bottles at enrollment. Timing of bottle filling was assessed using standardized sonographic screen captures. RESULTS: An interim look at statistics at n = 20 patients indicated that original conjectures from pilot data were conservative and smaller sample size was sufficient to stop the study and conduct the analyses. Specifically, SD = 54 s, diff = 49 s, two-tailed alpha-level 0.05, and power 80% required n = 21 patients per group. Plastic containers had a statistically significantly lower average filling time per bottle (162.7 ± 53.3 s) compared to glass (212.2 ± 50.4 s) (p = 0.003). Viscosity was calculated for each specimen and did not affect the statistical significance of the results (p = 0.32). CONCLUSION: Plastic containers have 50 s time savings of per bottle filling time as compared to glass bottles as theorized based on their faster flow rate. This holds true in both an ex vivo setting and in patients and can have important downstream impacts on patient throughput, provider efficiency and system wide cost savings.

Characterization of Small (< 4 cm) Focal Renal Lesions: Diagnostic Accuracy of Spectral Analysis Using Single-Phase Contrast-Enhanced Dual-Energy CT.

OBJECTIVE: The purpose of this study is to determine whether single-phase contrast-enhanced dual-energy quantitative spectral analysis improves the accuracy of diagnosis of small (< 4.0 cm) renal lesions, compared with conventional single-energy attenuation measurements. MATERIALS AND METHODS: In this retrospective study, 136 consecutive patients (95 men and 41 women; mean age, 54 years) with 144 renal lesions (111 benign and 33 malignant) underwent single-energy unenhanced and dual-energy contrast-enhanced CT of the abdomen. For each renal lesion, attenuation measurements were obtained, and an attenuation change of 15 HU or greater was considered evidence of enhancement. Dual-energy spectral attenuation curves were generated for each lesion. The slope of each curve was measured between 40 and 50 keV (λHU40-50), 40 and 70 keV (λHU40-70), and 40 and 140 keV (λHU40-140). Mean lesion attenuation values and spectral attenuation curve parameters were compared between benign and malignant renal lesions by use of the two-sample t test. Diagnostic accuracy was assessed and validated using cross-validation analysis. RESULTS: With the use of cross-validated optimal thresholds at 100% sensitivity, specificity for differentiating between benign and malignant renal lesions improved significantly when both λHU40-70 and λHU40-140 were used, compared with conventional enhancement measurements (93% [103/111; 95% CI, 86-97%] vs 81% [90/111; 95% CI, 73-88%]) (p = 0.02). The sensitivity of λHU40-70 and λHU40-140 was also higher than that of conventional enhancement measurements, although it was not statistically significant. CONCLUSION: Single-phase contrast-enhanced dual-energy quantitative spectral analysis significantly improves the specificity for characterization of small (< 4.0 cm) renal lesions, compared with conventional single-energy attenuation measurements.

Gray-scale inversion radiographic display for the detection of pulmonary nodules on chest radiographs.

The purpose of this study was to investigate gray-scale inversion in nodule detection on chest radiography. Simulated nodules were superimposed randomly onto normal chest radiographs. Six radiologists interpreted 144 chest radiographs during three reading sessions: traditional presentation, inverted gray-scale, and a choice session allowing use of traditional and gray-scale inverted views. Sensitivity and specificity were used to assess accuracy based on presence or absence of a nodule. Gray-scale inversion and choice display sessions resulted in significantly higher nodule detection specificity and decreased sensitivity compared to traditional display. Gray-scale inversion may decrease false-positive nodule findings during chest X-ray interpretation.

Diagnosis of renal angiomyolipoma with hounsfield unit thresholds: effect of size of region of interest and nephrographic phase imaging.

PURPOSE: To retrospectively determine the optimal Hounsfield unit threshold and region of interest (ROI) size required to accurately diagnose renal angiomyolipoma (AML) and differentiate it from renal cell carcinoma (RCC). MATERIALS AND METHODS: This retrospective study was institutional review board approved and HIPAA compliant, and the requirement for written informed patient consent was waived. The radiologic reports on 4502 dual-phase abdominal computed tomography (CT) examinations (nonenhanced and nephrographic phases, 5-mm collimation, 120-140 kVp, variable milliampere-second settings) performed in 2872 patients from June 2002 through October 2007 were reviewed. Solid-component masses reported as suspicious for RCC or AML were correlated with histologic and/or follow-up imaging findings. ROIs of three different sizes-tiny (8-13 mm(2)), small (19-24 mm(2)), and medium (30-35 mm(2))-were drawn in the lowest-attenuation focus on images obtained during both phases. The test characteristics (sensitivity, specificity, positive predictive value, negative predictive value, false-positive rate, false-negative rate) of multiple attenuation thresholds at each combination of ROI size and contrast enhancement phase were calculated, and receiver operating characteristic (ROC) curves were derived. Areas under the ROC curve were calculated. RESULTS: There were 217 RCCs and 65 AMLs. With an attenuation threshold of -10 HU or lower at nonenhanced CT, RCC would be misdiagnosed as AML in 11 (5.1%) cases, one (0.5%) case, and one (0.5%) case with use of the tiny, small, and medium ROIs, respectively. With use of the tiny, small, and medium ROIs, misdiagnosis rates would be 2.3%, 0.5%, and 0.5%, respectively, at a threshold of -15 HU or lower and 1.8%, 0%, and 0%, respectively, at a threshold of -20 HU or lower. Areas under the ROC curve for the nonenhanced phase images (range, 0.874-0.889) were superior to those for the nephrographic phase images (range, 0.790-0.826). CONCLUSION: Nonenhanced CT images were superior to nephrographic phase CT images for the diagnosis of AML. An attenuation threshold of -10 HU or lower with an ROI of at least 19-24 mm(2) is optimal for the diagnosis of AML. This threshold is not accurate with use of smaller (8-13-mm(2)) ROIs.

Imaging tumors of the penis and urethra.

In penile and urethral cancers, imaging has come to play a crucial role in enhancing the precision of clinical staging and facilitating optimal surgical planning. Over the years, great improvements have occurred in imaging. High-resolution magnetic resonance imaging (MRI) now represents the gold standard for evaluating the primary tumor and its local extension. Lymphotropic nanoparticle-enhanced MRI, dynamic sentinel lymph node biopsy, and ultrasonography with fine-needle aspiration seem to be the superior modalities for detecting malignant regional lymph nodes. Positron emission tomography combined with computed tomography has shown great promise as a whole body screen for the detection of distant metastases. Ultimately, the ability of imaging to augment clinical evaluation and enhance the accuracy of staging penile and urethral cancers will translate into improved surgical decision making and overall superior patient outcomes.

Helical CT for nephrolithiasis and ureterolithiasis: comparison of conventional and reduced radiation-dose techniques.

PURPOSE: To determine the accuracy of unenhanced helical computed tomography (CT) performed at reduced milliampere-second, and therefore at a reduced patient radiation dose, by using conventional unenhanced helical CT as the standard. MATERIALS AND METHODS: Fifty patients with acute flank pain who weighed less than 200 lb (90 kg) were prospectively recruited for this study. Conventional helical CT scans were obtained with patients in the prone position by using 5-mm-thick sections, 140 kVp, 135-208 mAs (mean, 160 mAs), and a pitch of 1.5 (single-detector row CT) or 0.75 (multi-detector row CT, 4 x 5-mm detector configuration). Conventional CT was immediately followed by low-dose scanning, whereby the tube current was reduced to 100 mA (mean, 76 mAs). All other technical parameters and anatomic coverage remained constant. Three independent readers who were blinded to patient identity interpreted the scans in random order. The observers noted the location, size, and number of calculi; secondary signs of obstruction; and other clinically relevant findings. High- and low-dose scans were compared by using paired t tests and the signed rank test. RESULTS: Calculi were found in 33 (66%) patients; 25 (50%) had renal calculi and 19 (38%) had an obstructing ureteral calculus. The accuracy rates (averaged over the three readers) for determining the various findings on the low-dose scan compared with the high-dose scan were as follows: nephrolithiasis, 91%; ureterolithiasis, 94%; obstruction, 91%; and normal findings, 92%. When interpretations between readers were compared, agreement rates were 90%-95% for standard-dose scans and 90%-92% for reduced-dose scans (P >.5). Uncomplicated mild diverticulitis was found in three patients. No other clinically important abnormality was identified. A reduction in the tube current to 100 mA resulted in a dose reduction of 25% for multi-detector row CT and 42% for single-detector row CT. CONCLUSION: In patients who weighed less than 200 lb, unenhanced helical CT performed at a reduced tube current of 100 mA, and therefore at a reduced patient dose, resulted in scans of high accuracy.