Improvements in lumbar spine MRI at 3 T using parallel transmission.

OBJECTIVE: Parallel transmission MRI at 3 T improves image quality by reducing dielectric effects with radiofrequency shimming. The purpose of this study was to determine whether parallel transmission MRI improves signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in lumbar spine MRI at 3 T. MATERIALS AND METHODS: Ten healthy volunteers underwent T1-weighted MRI and nine healthy volunteers underwent T2-weighted MRI of the lumbar spine. Sagittal and axial T1- and T2-weighted images were acquired using parallel transmission MRI and conventional MRI. The percentage improvements in SNR and CNR were calculated, and statistical significance was determined using a two-tailed Student t test with p < 0.05 for significance. RESULTS: The CNR and SNR showed statistically significant improvements at all levels of the lumbar spine except SNR at T11 on axial T2-weighted imaging. For sagittal T1-weighted imaging, the average improvement with parallel transmission MRI was 53% in CNR and 19% in SNR. For axial T1-weighted imaging, the average improvement was 48% in CNR and 23% in SNR. For sagittal T2-weighted imaging, the average CNR improvement was 38% and the average SNR improvement, 20%. For axial T2-weighted scans, the average percentage improvement in CNR was greater than 100% and the average SNR improvement was 18% with parallel transmission MRI. CONCLUSION: The parallel transmission sequence improves image quality of lumbar spine MRI at 3 T, which is quantitatively supported by statistically significant improvements in SNR and CNR.

Discrepancy rates of on-call radiology residents' interpretations of CT angiography studies of the neck and circle of Willis.

OBJECTIVE: The purpose of our study was to determine the discrepancy rates of radiology residents' interpretations of emergent CT angiography (CTA) studies of the neck and circle of Willis and to assess any adverse clinical outcomes. MATERIALS AND METHODS: Five hundred thirty-eight CTA studies (287 circle of Willis and 251 neck) ordered emergently after hours and given preliminary readings by radiology residents from January 1, 2006, through December 31, 2007, were retrospectively reviewed. Discrepancies between the interpretations of radiology residents and the final reports of neuroradiology attending physicians were classified as either false-negatives (failure to recognize abnormalities) or false-positives (misinterpreting normal scans as abnormal). Discrepancies that could affect patient care or clinical care were considered major. RESULTS: Overall, the discrepancy rate was 13.6% for circle of Willis CTA and 13.5% for neck CTA. The misinterpretation rate of first-year residents was 19.5%, which was statistically significant compared with more senior-level residents (p = 0.05). There were 57 false-negative interpretations. The most common misses were stenosis greater than 50% (n = 16) and aneurysm (n = 15), and the most common false-positive was overcalling a potential intracranial aneurysm (n = 7). No adverse clinical outcomes were detected. CONCLUSION: The discrepancy rate between interpretations by on-call radiology residents and attending physicians of neuroradiology CTA studies was higher than expected at 13.6%, with a statistically significant greater miss rate among the most junior residents, which may be mitigated by recent changes with respect to the radiology residents' overnight call. No adverse clinical outcome was detected.

Discrepancy rates of radiology resident interpretations of on-call neuroradiology MR imaging studies.

PURPOSE: To determine the discrepancy rates of radiology residents interpreting emergent neuroradiology magnetic resonance (MR) imaging studies and to assess any adverse clinical outcomes. MATERIALS AND METHODS: Three hundred sixty-one brain and spine MR imaging and MR angiographic examinations that were ordered emergently after hours and given preliminary interpretations by radiology residents were retrospectively reviewed from December 1, 2006 to May 31, 2007 with institutional review board approval. Discrepancies between the interpretations of radiology residents and the final reports of attending neuroradiologists were classified as either false-negative (FN, failure to recognize abnormalities) or false-positive (FP, misinterpreting normal images as abnormal). Discrepancies that could affect patient care or clinical outcome were considered major. RESULTS: Overall, the agreement rate was 92.8%, the overall discrepancy rate was 7.2%, the major disagreement rate was 4.2%, and the minor disagreement rate was 2.2%. Misinterpretations among 1st-year residents on call were significant (P < .04) when compared with more senior-level residents. There were 23 FN interpretations. The most common misses were acute stroke (n = 3), aneurysm (n = 3), vascular occlusion (n = 3), and disk herniation (n = 2). There were only three FP interpretations (misdiagnoses of syrinx, arachnoiditis, and acute infarct). CONCLUSION: There was no adverse clinical outcome as a result of misinterpretations, owing in part to rapid turnaround time for final reporting. Level of residency training has a significant effect on the rate of discrepancy, which may be mitigated by recent changes regarding 1st-year radiology residents' overnight call.

Variable osteology of the sixth cervical vertebra in relation to stellate ganglion block.

BACKGROUND AND OBJECTIVES: Stellate ganglion block is often carried out using palpation of surface landmarks to guide needle placement. However, anatomic variation of the surface landmarks used is common and block failure has been reported in as many as 30% of patients, even when the surface landmarks that guide needle placement can be easily identified. METHODS: Computed tomography (CT) images of the cervical spine of 70 adult patients were examined to measure the distances in the coronal and sagittal planes between various points on the cricoid cartilage, anterior tubercle, posterior tubercle, and nadir of the vertebral gutter. The width of the tubercle in the caudal and cephalad plane was determined through multiplanar reformatted CT images in 6 randomly chosen patients. RESULTS: The mean distance from the lateral margin of the cricoid cartilage laterally to the anterior tubercle was 13 +/- 5 mm (range 3-22 mm) in men and 12 +/- 3 mm (range 6-22 mm) in women. The mean depth of the anterior tubercle as measured posteriorly from the midpoint of the trachea was 20 +/- 4 (range 10-33 mm) in men and 19 +/- 4 mm (range 9-33 mm) in women. The maximal and minimal cephalad-caudad dimensions of the transverse process of C6 were 9.3 +/- 0.3 mm, and 6.7 +/- 0.3 mm, respectively. CONCLUSIONS: Large variability was observed in the size and location of the landmarks used for needle placement during stellate ganglion block. Placement of the needle medially where the transverse process joins the lateral margin of the vertebral body provides a larger bony target that may potentially provide a safer, more reliable block.