Interpretation of head CT scans in the emergency department by fellows versus general staff non-neuroradiologists: a closer look at the effectiveness of a quality control program

Prior studies have evaluated discordance rates among radiology residents in interpretation of head computed tomograms (CTs). To our knowledge, there has been no study to compare performance among first-year fellows and more experienced general staff radiologists. This study will compare performances of these groups and evaluate the effect of a redundant system as part of a quality control program. Retrospective review of 3,886 consecutive head CTs in the Emergency Department from 7/01/04 to 6/30/2005 was performed. Fellows interpreted 2,150 and general staff radiologists 1,736 cases. Staff radiologist mean experience was 4 years (2-10 years). All primary interpretations were over-read by staff neuroradiologists (>10 years experience) as quality control. Discrepancies were divided into "major discordance" and "minor discordance." Major discordance is defined as a misread occurred that potentially delayed clinical management and thus may have incurred in mortality or disability. Minor discordance is defined as if there was no change in clinical management or impact on the patient's outcome. The patient electronic medical records were obtained and retrospectively reviewed to identify if there was an acute change in clinical management. Overall discordance rate of both groups was 2.7% (103/3,886), 0.3% major false negative (10/3,886), 1.7% minor false negative (65/3,886), 0.4% false positive (15/3,886). Fellows overall discordance rate was 2.6% (55/2,150) with major false negatives 4/2,150 (0.2%) and 2.8% (48/1,736) for general staff radiologists with 6/1736 (0.3%) major false negatives, p values 0.69 and 0.14, respectively. Three out of ten major false negatives were confirmed with the quality assurance interpretation on follow-up studies; four cases were in agreement with initial interpretation. Performance among first-year fellows and general staff radiologists in interpretation of head CTs was highly accurate (97.3%) without statistically significant difference between the groups. The overall relatively low discrepant rate between fellowship trainees and generalist staffs, as well as the negligible change in clinical management, suggests little utility in over-reads of head CT scans by the neuroradiology service as part of a year-round quality control program. However, because of a relative high discrepant rate in the early months of fellowship training (>5%) in our study, it may be wise to implement a quality assurance program in the first few months to improve patient care. Increasing over-reading rate may reduce false negative rate, as the overall false positive rate is relatively low (<0.5%).

Structural and functional mutations of the perlecan gene cause Schwartz-Jampel syndrome, with myotonic myopathy and chondrodysplasia

Perlecan, a large heparan sulfate proteoglycan, is a component of the basement membrane and other extracellular matrices and has been implicated in multiple biological functions. Mutations in the perlecan gene (HSPG2) cause two classes of skeletal disorders: the relatively mild Schwartz-Jampel syndrome (SJS) and severe neonatal lethal dyssegmental dysplasia, Silverman-Handmaker type (DDSH). SJS is an autosomal recessive skeletal dysplasia characterized by varying degrees of myotonia and chondrodysplasia, and patients with SJS survive. The molecular mechanism underlying the chondrodystrophic myotonia phenotype of SJS is unknown. In the present report, we identify five different mutations that resulted in various forms of perlecan in three unrelated patients with SJS. Heterozygous mutations in two patients with SJS either produced truncated perlecan that lacked domain V or significantly reduced levels of wild-type perlecan. The third patient had a homozygous 7-kb deletion that resulted in reduced amounts of nearly full-length perlecan. Unlike DDSH, the SJS mutations result in different forms of perlecan in reduced levels that are secreted to the extracellular matrix and are likely partially functional. These findings suggest that perlecan has an important role in neuromuscular function and cartilage formation, and they define the molecular basis involved in the difference in the phenotypic severity between DDSH and SJS.

Dyssegmental dysplasia, Silverman-Handmaker type, is caused by functional null mutations of the perlecan gene

Perlecan is a large heparan sulfate (HS) proteoglycan present in all basement membranes and in some other tissues such as cartilage, and is implicated in cell growth and differentiation. Mice lacking the perlecan gene (Hspg2) have a severe chondrodysplasia with dyssegmental ossification of the spine and show radiographic, clinical and chondro-osseous morphology similar to a lethal autosomal recessive disorder in humans termed dyssegmental dysplasia, Silverman-Handmaker type (DDSH; MIM 224410). Here we report a homozygous, 89-bp duplication in exon 34 of HSPG2 in a pair of siblings with DDSH born to consanguineous parents, and heterozygous point mutations in the 5' donor site of intron 52 and in the middle of exon 73 in a third, unrelated patient, causing skipping of the entire exons 52 and 73 of the HSPG2 transcript, respectively. These mutations are predicted to cause a frameshift, resulting in a truncated protein core. The cartilage matrix from these patients stained poorly with antibody specific for perlecan, but there was staining of intracellular inclusion bodies. Biochemically, truncated perlecan was not secreted by the patient fibroblasts, but was degraded to smaller fragments within the cells. Thus, DDSH is caused by a functional null mutation of HSPG2. Our findings demonstrate the critical role of perlecan in cartilage development.

Fitting characteristics of 1-day and 14-day Acuvue disposable contact lenses

The fitting characteristics of 1-day Acuvue disposable soft contact lenses (SCLs) [base curve (BC) 9.0 mm, diameter 14.2 mm] and 14-day Acuvue disposable SCLa (BC 8.8 mm, diameter 14.0 mm) were evaluated and compared with respect to lens centration and post-blink movement in primary gaze and in upgaze. In this double-blind study 25 successful daily wearers of either the 1-day lens or the 14-day lens with the same parameters were randomly fit with three 1-day lenses and three 14-day lenses for a total of 6 lenses per eye. The lene fit was evaluated 5 min after insertion. Lens centration was assessed by measuring temporal, nasal, superior and inferior limbal coverage, and then comparing the net horizontal centration (temporal minus nasal coverage) and the net vertical centration (superior minus inferior coverage) of the 1-day and 14-day lenses. There was no significant difference between the two lenses in terms of temporal, superior, and inferior limbal coverage (p > 0.05). However, the 1-day lens showed statistically more nasal coverage (p < 0.05). No statistically significant difference in movement or in horizontal and vertical differences in centration were found (p > 0.05). Although our findings indicate a subtle statistical difference in fitting characteristics, clinically the two lenses should provide similar fits.

Assessment of osteosarcoma response to preoperative chemotherapy using dynamic FLASH gadolinium-DTPA-enhanced magnetic resonance mapping

RATIONALE AND OBJECTIVES

To improve the accuracy of magnetic resonance imaging (MRI) in evaluating the response of osteosarcomas to preoperative chemotherapy, the authors developed a technique of mapping tumor necrosis and viability by quantitating slope values of gadolinium-DTPA (Gd-DTPA) uptake on dynamic fast low-angle shot (FLASH) images.

METHODS

Dynamic contrast-enhanced FLASH imaging of a single representative plane was performed on six osteosarcomas. Tumors were mapped by dividing resultant images into contiguous regions of interest and deriving slopes representing percentage increase in signal intensity (SI) per minute over the baseline for each region. The results were compared with estimations of viable tumor volume on subtracted Gd-DTPA-enhanced T1-weighted images and histologic maps of necrotic and viable tumor.

RESULTS

Dynamic FLASH estimations of percent tumor necrosis using a critical slope value of 45% per minute correctly predicted histologic response to chemotherapy in all six patients. Comparison of dynamic FLASH and histologic maps showed a high degree of correlation. Static enhanced T1-weighted images overestimated the amount of residual viable tumor.

CONCLUSIONS

Dynamic FLASH Gd-DTPA-enhanced mapping is a potentially useful noninvasive method of quantitating tumor response to chemotherapy.

Magnetic resonance imaging of disseminated bone marrow disease in patients treated for malignancy

Magnetic resonance imaging (MRI) is a sensitive method for the diagnosis of bone marrow abnormalities, but its usefulness in detecting active disseminated cancer in this tissue in treated patients has not been determined. We therefore examined 14 children who had been treated for disseminated bone marrow involvement by neuroblastoma (n = 6), lymphoma (n = 3), Ewing's sarcoma (n = 3), osteosarcoma (n = 1), and leukemia (n = 1). MRI studies were performed at 21 marrow sites to evaluate residual or recurrent tumor and were correlated with histologic material from the same site. T1- and T2-weighted sequences were employed in 21 and 14 studies, respectively; short tau inversion recovery (STIR) in 18; and static gadolinium diethylene triamine pentaacetic acid (Gd-DPTA)-enhanced. T1-weighted sequences in 13. All MRI studies showed an altered bone marrow signal. Technetium 99m methylene diphosphonate (99mTc-MDP) bone scintigraphy was also performed (19 studies). On histologic examination, 7 marrow specimens contained tumor, and 14 did not. Of the 7 tumor-positive lesions, all T1-weighted, 4 of 6 T2-weighted, and all 6 STIR sequences showed abnormal signal; all 5 Gd-DTPA-enhanced. T1-weighted sequences showed enhancement of the lesion. However, abnormal signals were also observed on all T1-weighted, 6 of 8 T2-weighted, 11 of 12 STIR, and 5 of 8 Gd-DTPA-enhanced, T1-weighted images of the tumor-negative sites. In this clinical setting, MRI did not consistently differentiate changes associated with treatment from malignant disease.