Daniel J. Durand

Aging Impairs the Beneficial Effect of Granulocyte Colony-Stimulating Factor and Stem Cell Factor on Post-Myocardial Infarction Remodeling

Granulocyte colony–stimulating factor (G-CSF) and stem cell factor (SCF) are potential new therapies to ameliorate post–myocardial infarction (post-MI) remodeling, as they enhance endogenous cardiac repair mechanisms and decrease cardiomyocyte apoptosis. Because both of these pathways undergo alterations with increasing age, we hypothesized that therapeutic efficacy of G-CSF and SCF is impaired in old versus young adult rats. MI was induced in 6- and 20-month-old rats by permanent ligation of the left coronary artery. In young animals, G-CSF/SCF therapy stabilized and reversed a decline in cardiac function, attenuated left ventricular dilation, decreased infarct size, and reduced cardiomyocyte hypertrophy. Remarkably, these effects on cardiac structure and function were absent in aged rodents. This could not be attributed to ineffective mobilization of bone marrow cells or decreased quantity of c-Kit+ cells within the myocardium with aging. However, whereas the G-CSF/SCF cocktail reduced cardiac myocyte apoptosis in old as well as in young hearts, the degree of reduction was substantially less with age and the rate of cardiomyocyte apoptosis in old animals remained high despite cytokine treatment. These findings demonstrate that G-CSF/SCF lacks therapeutic efficacy in old animals by failing to offset periinfarct apoptosis and therefore raise important concerns regarding the efficacy of novel cytokine therapies in elderly individuals at greatest risk for adverse consequences of MI.

Proton MR Spectroscopy in Metabolic Assessment of Musculoskeletal Lesions

OBJECTIVE The purposes of this review are to describe the principles and method of MR spectroscopy, summarize current published data on musculoskeletal lesions, and report additional cases that have been analyzed with recently developed quantitative methods. CONCLUSION Proton MR spectroscopy can be used to identify key tissue metabolites and may serve as a useful adjunct to radiographic evaluation of musculoskeletal lesions. A pooled analysis of 122 musculoskeletal tumors revealed that a discrete choline peak has a sensitivity of 88% and specificity of 68% in the detection of malignancy. Modest improvements in diagnostic accuracy in 22 of 122 cases when absolute choline quantification was used encourage the pursuit of development of choline quantification methods.

The role of magnetic resonance imaging in the diagnostic evaluation of malignant peripheral nerve sheath tumors

BACKGROUND AND AIMS Malignant peripheral nerve sheath tumors (MPNSTs) are the leading cause of mortality in patients with neurofibromatosis type-1 (NF1)); however, they may also arise sporadically. Differences in magnetic resonance imaging (MRI) features between MPNSTs arising in NF1 subjects versus non-NF1 subjects have not been studied before. The accuracy of MRI in distinguishing MPNSTs from benign peripheral nerve sheath tumors (BPNSTs) has also been debated. The objective of this study was to determine the potential differentiating MRI features between (a) NF1-related and non-NF1-related MPNSTs and (b) MPNSTs and BPNSTs. MATERIALS AND METHODS We retrospectively evaluated the MRI studies of 21 patients (12 NF1 subjects and nine non-NF1 subjects) with MPNSTs and 35 patients with BPNSTs. In all studies, the lesions were assessed in terms of size, margins, T1 and T2 signal characteristics, internal architecture, pattern of contrast enhancement, invasion of adjacent structures and necrosis/cystic degeneration as well as for the presence of tail-, target- and split-fat signs. RESULTS MPNSTs of NF1 subjects occurred at an earlier age and displayed a higher incidence of necrosis/cystic degeneration compared with MPNSTs of non-NF1 subjects. Compared with BPNSTs, MPNSTs were significantly larger at the time of diagnosis and demonstrated a higher incidence of ill-defined margins (specificity 91%, sensitivity 52%) and invasion of adjacent structures (specificity 100%, sensitivity 43%). CONCLUSIONS Differences exist between NF1-related and non-NF1-related MPNSTs regarding the age of occurrence and MRI appearance. In the MRI evaluation of peripheral nerve sheath tumors, the presence of ill-defined tumor margins and/or invasion of adjacent structures are highly specific for malignancy.

Increased Error Rates in Preliminary Reports Issued by Radiology Residents Working More Than 10 Consecutive Hours Overnight

RATIONALE AND OBJECTIVES To determine if the rate of major discrepancies between resident preliminary reports and faculty final reports increases during the final hours of consecutive 12-hour overnight call shifts. MATERIALS AND METHODS Institutional review board exemption status was obtained for this study. All overnight radiology reports interpreted by residents on-call between January 2010 and June 2010 were reviewed by board-certified faculty and categorized as major discrepancies if they contained a change in interpretation with the potential to impact patient management or outcome. Initial determination of a major discrepancy was at the discretion of individual faculty radiologists based on this general definition. Studies categorized as major discrepancies were secondarily reviewed by the residency program director (M.H.S.) to ensure consistent application of the major discrepancy designation. Multiple variables associated with each report were collected and analyzed, including the time of preliminary interpretation, time into shift study was interpreted, volume of studies interpreted during each shift, day of the week, patient location (inpatient or emergency department), block of shift (2-hour blocks for 12-hour shifts), imaging modality, patient age and gender, resident identification, and faculty identification. Univariate risk factor analysis was performed to determine the optimal data format of each variable (ie, continuous versus categorical). A multivariate logistic regression model was then constructed to account for confounding between variables and identify independent risk factors for major discrepancies. RESULTS We analyzed 8062 preliminary resident reports with 79 major discrepancies (1.0%). There was a statistically significant increase in major discrepancy rate during the final 2 hours of consecutive 12-hour call shifts. Multivariate analysis confirmed that interpretation during the last 2 hours of 12-hour call shifts (odds ratio (OR) 1.94, 95% confidence interval (CI) 1.18-3.21), cross-sectional imaging modality (OR 5.38, 95% CI 3.22-8.98), and inpatient location (OR 1.81, 95% CI 1.02-3.20) were independent risk factors for major discrepancy. CONCLUSIONS In a single academic medical center, major discrepancies in resident preliminary reports increased significantly during the final 2 hours of consecutive 12-hour overnight call shifts. This finding could be related to either fatigue or circadian desynchronization. Discrimination of these two potential etiologies requires additional investigation as major discrepancies in resident reports have the potential to negatively impact patient care/outcome. Cross-sectional imaging modalities including computed tomography and ultrasound (versus conventional radiography), as well as inpatient location (versus Emergency Department location), were also associated with significantly higher major discrepancy rates.

A Rational Approach to the Clinical Use of Cumulative Effective Dose Estimates

OBJECTIVE This article will address ongoing efforts to track cumulative dose estimates of patient radiation exposure that have the potential to transform radiation protection research. CONCLUSION There is no clear consensus on how to use this information clinically. A rational consideration of this question reveals that until the linear no-threshold model is supplanted, cumulative dose estimates are of little clinical relevance and never constitute a logical reason to avoid an imaging evaluation that is otherwise medically indicated.

Detection of Cytomegalovirus DNA in Plasma as an Adjunct Diagnostic for Gastrointestinal Tract Disease in Kidney and Liver Transplant Recipients

BACKGROUND Cytomegalovirus (CMV) disease is the most common infectious complication after solid organ transplantation, frequently affecting the gastrointestinal (GI) tract. There are limited data on quantitative polymerase chain reaction (qPCR) for plasma CMV DNA as an adjunct diagnostic method for GI tract disease in kidney and liver transplant recipients. METHODS We reviewed all records of adult kidney and liver transplant recipients with a GI tract biopsy and plasma CMV qPCR result within 15 days of biopsy during a 6.5-year period at our center. CMV GI tract disease was defined as histopathologic evidence of CMV on biopsy by immunohistochemistry or visualization of inclusion bodies. RESULTS GI tract biopsy and qPCR results were available for 81 kidney and liver transplant recipients; 20 cases of confirmed CMV GI tract disease were identified. Overall, the sensitivity of qPCR for diagnosing CMV GI tract disease was 85% (95% confidence interval [CI], 61%-96%), and the specificity was 95% (95% CI, 85%-99%). For CMV-seronegative recipients (R(-)) with CMV-seropositive donors (D(+)), the sensitivity of qPCR was 100% (95% CI, 59%-99%), and the specificity was 80% (95% CI, 30%-99%). The lowest sensitivity was observed in CMV D(+)/R(+) cases (72.7%; 95% CI, 39%-93%). The mean plasma CMV copy number in patients with GI tract disease was 3.84 log10 (38 334 copies/mL). CONCLUSIONS Plasma CMV qPCR had good sensitivity and excellent specificity for CMV GI tract disease in kidney and liver transplant recipients. Its sensitivity was 100% in CMV D(+)/R(-) cases but 72.7% in CMV D(+)/R(+) cases. This variation in assay performance according to host serostatus may reflect differences in disease pathogenesis.

Utilization Strategies for Cumulative Dose Estimates: A Review and Rational Assessment

Over the past several years, the cancer risks associated with radiation from diagnostic imaging have received increased attention in both the medical literature and the lay press. In the midst of this heightened scrutiny, there has been growing support for the idea of tracking cumulative dose estimates that longitudinally document the accumulated medical radiation exposure of each individual patient. The authors review the current consensus model of radiation-induced carcinogenesis and use this framework to provide a rational assessment of several potential cumulative dose estimate utilization strategies.

Provider Cost Transparency Alone Has No Impact on Inpatient Imaging Utilization

PURPOSE The aim of this study was to determine whether presenting providers with cost information at the point of order entry significantly influences imaging utilization. METHODS Using data from fiscal year 2007, the 10 most frequently ordered imaging tests were identified. Five of these were randomly assigned to the active cost display group and 5 to the control group. During a 6-month baseline period from November 10, 2008, to May 9, 2009, no costs were displayed. During a seasonally matched intervention period from November 10, 2009, to May 9, 2010, costs were displayed only for tests in the active group. At the conclusion of the study, the radiology information system was queried to determine the number of orders executed for all tests during both periods. The main outcome measure was the mean relative utilization change between the control and intervention periods for the active group vs the control group. An additional measure was the correlation between test cost and utilization change in the active group vs the control group. RESULTS The mean utilization change was +2.8 ± 4.4% for the active group and -3.0 ± 5.5% for the control group, with no significant difference between the two groups (P = .10, Students t-test). There was also no significant difference in the correlation between test cost and utilization change for the active group vs the control group (P = .25, Fishers z-test). On the basis of the observed standard deviations, this study had 90% power to detect an 11.8% difference in mean relative utilization change between groups. CONCLUSIONS Provider cost transparency alone does not significantly influence inpatient imaging utilization.

Mandatory Child Life Consultation and Its Impact on Pediatric MRI Workflow in an Academic Medical Center.

Pediatric patients undergoing MRI often require general anesthesia, which may improve image quality but is associated with significant medical risk and economic cost. It has previously been shown that certified child life specialists using high-tech interventions (eg, MRI-compatible video goggles) significantly reduce the number of pediatric MRI patients who require sedation. Most imaging centers lack such technology, however, and it remains unclear whether simpler and less costly child life interventions may be equally effective in avoiding general anesthesia. The aim of this study was to assess the impact of requiring mandatory child life evaluation for all patients aged 5 to 18 years undergoing MRI before referral for general anesthesia. Inserting this simple step into the scheduling workflow significantly reduced the use of general anesthesia in this population: general anesthesia was required in 564 of 2,433 MRI cases during the 1-year baseline period compared with 484 of 2,526 cases during the 1-year intervention period (P < .01 by z test for proportions; absolute reduction, 4.0%; relative reduction, 14.8%). The authors estimate that instituting mandatory child life evaluation avoided the use of general anesthesia in approximately 102 patients during the intervention period. Further subgroup analysis revealed that avoidance of general anesthesia was highly significant in the 5- to 10-year-old age group, whereas those aged 11 to 18 years experienced only a trend toward modestly decreased use of general anesthesia. These results suggest that mandatory evaluation for standard child life interventions is a worthwhile step that can save many children from unnecessary exposure to the risks, cost, and inconvenience of general anesthesia.

Subsurface Tissue Lesions Created Using an Nd:YAG Laser and Cryogen Cooling

BACKGROUND AND PURPOSE Cooling methods are commonly used in dermatology to protect the skin surface during cosmetic laser procedures. This study investigated deep laser heating of tissue in combination with cryogen cooling of the surface for potential noninvasive targeting of subsurface tissue structures in urology. MATERIALS AND METHODS Porcine liver and skin were studied because they represent simple and difficult tissue models, respectively, for subsurface lesion production. Gross and histologic methods were used to measure lesion dimensions. RESULTS Liver lesions measured 4.9 +/- 1.2 mm in diameter, while preserving the tissue surface to a depth of 2.1 +/- 0.4 mm (N = 5). Surface temperatures remained below 40 degrees C, while lesion temperatures ranged from 60 to 70 degrees C. Skin lesions measured 4.1 +/- 0.6 mm, while preserving the skin surface to a depth of 1.2 +/- 0.2 mm (N = 4). CONCLUSION This technique may prove useful to target subsurface anatomic structures in urology.