Faculty Bibliography

BACKGROUND: Hospital care on weekends has been associated with delays in care, reduced quality, and poor clinical outcomes. OBJECTIVE: The purpose of this study was to evaluate the impact of a weekend hospital intervention on processes of care and clinical outcomes. The multifaceted intervention included expanded weekend diagnostic services, improved weekend discharge processes, and increased physician and care management services on weekends. DESIGN AND PATIENTS: This was an interrupted time series observational study of adult non-obstetric patients hospitalized at a single academic medical center between January 2011 and January 2014. The study included 18 months prior to and 19 months following the implementation of the intervention. Data were analyzed using segmented regression analysis with adjustment for confounders. MAIN MEASURES: The primary outcome was average length of stay. Secondary outcomes included percent of patients discharged on weekends, 30-day readmission rate, and in-hospital mortality rate. KEY RESULTS: The study included 57,163 hospitalizations. Following implementation of the intervention, average length of stay decreased by 13 % (95 % CI 10-15 %) and continued to decrease by 1 % (95 % CI 1-2 %) per month as compared to the underlying time trend. The proportion of weekend discharges increased by 12 % (95 % CI 2-22 %) at the time of the intervention and continued to increase by 2 % (95 % CI 1-3 %) per month thereafter. The intervention had no impact on readmissions or mortality. During the post-implementation period, the hospital was evacuated and closed for 2 months due to damage from Hurricane Sandy, and a new hospital-wide electronic health record was introduced. The contributions of these events to our findings are not known. We observed a lower inpatient census and found differences in patient characteristics, including higher rates of Medicaid insurance and comorbidities, in the post-Hurricane Sandy period as compared to the pre-Sandy period. CONCLUSIONS: The intervention was associated with a reduction in length of stay and an increase in weekend discharges. Our longitudinal study also illuminated the challenges of evaluating the effectiveness of a large-scale intervention in a real-world hospital setting.

PURPOSE: To prospectively determine the dependence of renal cyst pseudoenhancement on multidetector computed tomographic (CT) scanner type and convolution kernel in a phantom model. MATERIALS AND METHODS: A customized anthropomorphic phantom was created to accept interchangeable 40-, 140-, and 240-HU renal inserts that contained stacked 0- and 50-HU cylindric cysts measuring 7, 10, and 15 mm in diameter. Each phantom and insert was scanned with five different multidetector CT scanners on five separate occasions by using 120 kVp, low and high tube current settings, 3.00-3.75-mm collimation, and standard and high-spatial-resolution kernels. A total of 2340 CT attenuation measurements were obtained by using standardized regions of interest. The effect of multidetector CT imaging regimen, tube current, cyst diameter, and renal attenuation on pseudoenhancement incidence was assessed by using generalized estimating equations based on a binary logistic regression model. Within this framework, a Bonferroni multiple comparison correction was used to assess pseudoenhancement frequency differences among imaging regimens. RESULTS: Pseudoenhancement occurred in both 0- and 50-HU cysts; was significantly correlated with multidetector CT imaging regimen (P<.0001), cyst diameter (P<.0001), and renal attenuation (P<or=.032); and was independent of tube current (P>.3). When convolution kernels on specific scanners were compared, significant differences (P<.04) between kernels were identified with all five scanners in terms of observed pseudoenhancement incidence. Generational differences in equipment were noted, with pseudoenhancement incidence ranging from 1.7% to 8.3%, 1.7% to 16.7%, and 18.3% to 56.7% across relevant kernels for three scanners from one manufacturer. CONCLUSION: Pseudoenhancement is strongly dependent on multidetector CT convolution kernel. Varying this parameter may mitigate this phenomenon, which is independent of volume-averaging effects

PURPOSE: To determine the dependence of absolute computed tomographic (CT) attenuation values on multi-detector row CT scanner type, convolution kernel, and tube current by using an anthropomorphic phantom. MATERIALS AND METHODS: A customized phantom was designed with tissue-equivalent materials to simulate contrast material-enhanced liver, spleen, pancreas, aorta, kidney, 0- and 50-HU cylindric renal cysts, muscle, and fat. The phantom was scanned with five multi-detector row CT scanners (LightSpeed QXi, GE Healthcare, Milwaukee, Wis; MX8000, Philips Medical Systems, Best, the Netherlands; and Volume Zoom, Sensation 16 and Sensation 64, Siemens Medical Solutions, Forchheim, Germany) on five separate occasions with 120 kVp, low and high tube current settings, 3.00-3.75-mm section thickness, 50% overlap, and standard and high-spatial-resolution kernels. Standardized regions of interest (ROIs) were used to obtain 3510 attenuation measurements. Attenuation dependence on scanner, kernel, and tube current was evaluated by using F tests derived with mixed-model regression. Within the mixed-model framework, the Tukey honestly significant difference procedure and a Bonferroni multiple comparison correction were used to assess differences among imaging regimens and tube current settings, respectively, in terms of tissue attenuation and ROI standard deviation. RESULTS: Tube current had no significant effect (P>.4) on observed tissue attenuation. Significant (P<.0001) differences were observed between imaging regimens with respect to mean attenuation for each tissue type. Convolution kernel modification had an inconsistent effect on tissue attenuation, depending on the scanner. All multi-detector row CT scanners displayed intrascanner variability in tissue attenuation (minimum range: 8.4 HU for fat tissue with the Sensation 16; maximum range: 63.4 HU for liver tissue with the Sensation 64). The scanners behaved differently at the lower range of the CT number scale, where 0-HU cyst attenuation ranged from -15.7 to 23.9 HU and one vendor's equipment showed significantly lower mean attenuation values. CONCLUSION: CT attenuation values vary significantly between different manufacturers' multi-detector row CT scanners, among different generations of multi-detector row CT scanning equipment, and with individual combinations of scanner and convolution kernel. Supplemental material: http://radiology.rsnajnls.org/cgi/content/full/242/1/109/DC1

OBJECTIVE: This study reviews the CT findings of Meckel's diverticulitis in 11 patients and, to our knowledge, represents the largest series of such cases reported to date. CONCLUSION: The inflamed Meckel's diverticulum may be visualized on CT in most patients, appearing as a blind-ending pouch of variable size and mural thickness and containing fluid, air, or particulate material with surrounding mesenteric inflammation. The location of the diverticulum may vary from the right lower quadrant to the mid abdomen, with most cases in this series located near midline. Optimal luminal opacification of the ileocecal bowel with oral contrast material facilitated detection of the diverticulum and also proved invaluable in enabling identification of the normal appendix. The diagnosis is most difficult in the setting of secondary intestinal obstruction

PURPOSE: To determine the sensitivity and specificity of computed tomographic (CT) criteria for differentiating benign from malignant stomach lesions in patients with a thickened gastric wall at CT. MATERIALS AND METHODS: A radiology department file search revealed 36 patients with a thickened gastric wall at CT who underwent double-contrast barium suspension upper gastrointestinal tract examinations within 6 weeks before or after CT. The authors reviewed the CT images without knowledge of the final radiologic, endoscopic, or pathologic findings to determine the degree of gastric wall thickening and the symmetry, distribution, and enhancement of the thickened wall. The sensitivity and specificity of these findings for detection of malignancy were calculated. RESULTS: Two of 36 patients had two gastric abnormalities each. The final diagnoses in the 38 cases were gastritis in 19, hiatal hernia in four, benign ulcer in three, benign (n = 3) or malignant (n = 8) gastric neoplasm in 11, and no gastric abnormality in one case. Mean wall thickness was 1.5 cm (range, 0.7-7.5 cm). The finding of gastric wall thickness of 1 cm or greater had a sensitivity of 100% but a specificity of only 42% for detection of malignant or potentially malignant stomach lesions. The finding of focal, eccentric, or enhancing wall thickening had a sensitivity of 93%, 71%, or 43%, respectively, and a specificity of 8%, 75%, or 88%, respectively, for detection of these lesions. Gastric wall thickening that was 1 cm or greater and was focal, eccentric, and enhancing had a specificity of 92% but a sensitivity of only 36% for detection of these lesions. CONCLUSION: Gastric wall thickness of 1 cm or greater at CT had a sensitivity of 100% but a specificity of less than 50% for detection of malignant or potentially malignant stomach lesions that necessitated further diagnostic evaluation

PURPOSE: To assess the accuracy and reproducibility of dual-phase helical computed tomography (CT) in enabling preoperative detection and characterization of surgically staged focal liver lesions. MATERIALS AND METHODS: Surgically and histopathologically proven liver lesions were evaluated by three experienced CT readers. These lesions were present in 77 patients who underwent dual-phase helical CT. Images were interpreted separately by the three blinded reviewers. Each lesion was graded on a nine-point scale of confidence, with 1 being definitely benign, 9 being definitely malignant, and 5 being indeterminate. The chi2 test was used to determine if the distribution of lesion classifications was different between readers. RESULTS: There was a total of 237 lesions: 73 were benign and 164 were malignant. Sensitivity for lesion detection was 69%, 70%, and 71% for the three reviewers, respectively. Specificity was 91%, 86%, and 90%, and the area under the curve for the alternative-free response receiver operating characteristic curve was 0.84, 0.83, and 0.85, respectively. The difference in the distributions of lesion classification between the three reviewers was not statistically significant (P =.67) as determined by chi2 analysis. CONCLUSION: Dual-phase CT has sensitivity of 69%-71% and high specificity (86%-91%) in enabling the detection and characterization of focal liver lesions. Interpretation is highly reproducible, as there is minimal variation between experienced reviewers

Pelvic inflammatory disease (PID) is a common medical problem, affecting nearly 1 million women each year. Although the radiology literature is replete with discussions of the sonographic manifestations of PID, little has been published regarding the computed tomographic (CT) appearances of this entity. CT findings in early PID include obscuration of the normal pelvic floor fascial planes, thickening of the uterosacral ligaments, cervicitis, oophoritis, salpingitis, and accumulation of simple fluid in the endometrial canal, fallopian tubes, and pelvis. As the disease progresses, this simple fluid may become complex and the inflammatory changes may progress to frank tubo-ovarian or pelvic abscesses. Reactive inflammation of adjacent structures is common and can manifest as small or large bowel ileus or obstruction, hydroureter and hydronephrosis, right upper quadrant inflammation (Fitz-Hugh-Curtis syndrome), or peritonitis. Familiarity with the CT appearances of these manifestations is important for timely diagnosis and treatment of PID and its complications