Faculty Bibliography

BACKGROUND AND PURPOSE: A temporal bone CT study in a patient with episodic mid-tone sensorineural hearing loss and tinnitus demonstrated absence of bone between the petrous internal carotid artery and the basal turn of the cochlea. The potential implications with respect to increasingly popular cochlear implant surgery compelled us to retrospectively analyze a series of temporal bone CT scans to establish typical measurements for this region, which we termed the 'cochlear-carotid interval' (CCI). METHODS: After IRB exemption, 2 observers independently measured the bony interval between the cochlea and the petrous internal carotid artery canal on coronal images from 30 consecutive temporal bone CT studies. The 1-mm thick coronal images were either acquired directly or were reconstructed from an axial dataset acquired at 0.75 or 0.6 mm section thickness. All measurements were performed by using electronic calipers on a Sienet MagicView VE 42 Siemens PACS station. Mixed model analysis of variance was used to evaluate differences between readers and sides with respect to the mean CCI but adjusted for age and accommodating the correlation among observations generated for the same subject. RESULTS: The patient in our case report had a right CCI of 0.2 mm and left CCI of 0.0 mm. In the other 30 patients, the right CCI ranged from 0.2 to 3.8 mm (mean, 1.2 +/- 0.8 mm; median, 0.9) and the left CCI from 0.2 to 5.0 mm (mean, 1.1 +/- 0.9 mm; median, 0.8). The CCI did not exhibit a significant association with subject age (P = .1336), and there were no significant differences between readers (P = .824) or sides (P = .350) in terms of mean CCI. CONCLUSION: The CCI varies widely between patients and may be as small as zero. Analysis of anatomic relationships suggests a potential relationship between small CCI and mid-tone sensorineural hearing loss, as in our reported patient. Preoperative knowledge of thin or absent bone between the cochlea and petrous carotid canal may help prevent inadvertent penetration of the carotid canal during cochlear implant surgery

PURPOSE: To evaluate signal-to-noise ratio (SNR) and neuroradiologists' subjective assessments of image quality in 3-Tesla (3-T) or phased-array MR systems that are now available for clinical neuroimaging. MATERIALS AND METHODS: Brain MR images of six normal volunteers were obtained on each of three scanners: a 1.5-T single-channel system, a 12-channel, phased-array system, and a 3-T single-channel system. Additionally, clinically optimized images acquired from 28 patients who underwent imaging in more than one of these systems were analyzed. SNRs were measured and image quality and artifact conspicuity were graded by two blinded readers. RESULTS: The phased-array system produced higher SNR than either the 1.5-T or the 3-T single-channel systems, and in no instance was it outperformed. Both blinded readers judged the phased-array images to be of higher quality than those produced by the single-channel systems, with significantly less artifact. The 3-T magnet produced images with high SNR, but with increased artifact conspicuity. The phased-array system markedly decreased acquisition times without introduction of artifacts. CONCLUSION: Both quantitatively and qualitatively, the phased-array system provided image quality superior to that of the 1.5-T and 3-T single-channel systems

BACKGROUND AND PURPOSE: Evaluation of the spinal cord is important in the diagnosis and follow-up of patients with multiple sclerosis. Our purpose was to investigate diffusion tensor imaging (DTI) changes in different regions of normal-appearing spinal cord (NASC) in relapsing-remitting multiple sclerosis (RRMS). METHODS: Axial DTI of the cervical spinal cord was performed in 24 patients with RRMS and 24 age- and sex-matched control subjects. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated in separate regions of interest (ROIs) in the anterior, lateral, and posterior spinal cord, bilaterally, and the central spinal cord, at the C2-C3 level. Patients and control subjects were compared with respect to FA and MD with the use of an exact Mann-Whitney test. Logistic regression and receiver operating characteristic (ROC) curve analysis assessed the utility of each measure for the diagnosis of RRMS. RESULTS: DTI metrics in areas of NASC in MS were significantly different in patients compared with control subjects; FA was lower in the lateral (mean +/- SD of 0.56 +/- 0.10 versus 0.69 +/- 0.09 in control subjects, P < .0001), posterior (0.52 +/- 0.11 versus 0.63 +/- 0.10, P < .0001), and central (0.53 +/- 0.10 versus 0.58 +/- 0.10, P = .049) NASC ROIs. Assessing DTI metrics in the diagnosis of MS, a sensitivity of 87.0% (95% confidence interval [CI], 66.4 to 97.1) and a specificity of 91.7% (95% CI, 73.0 to 98.7) were demonstrated. CONCLUSION: The NASC in RRMS demonstrates DTI changes. This may prove useful in detecting occult spinal cord pathology, predicting clinical course, and monitoring disease progression and therapeutic effect in MS

OBJECTIVE:To determine whether relative cerebral blood volume (rCBV) can predict patient outcome, specifically tumor progression, in low-grade gliomas (LGGs) and thus provide a second reference standard in the surgical and postsurgical management of LGGs. METHODS:Thirty-five patients with histologically diagnosed LGGs (21 low-grade astrocytomas and 14 low-grade oligodendrogliomas and low-grade mixed oligoastrocytomas) were studied with dynamic susceptibility contrast-enhanced perfusion magnetic resonance imaging. Wilcoxon tests were used to compare patients in different response categories (complete response, stable, progressive, death) with respect to baseline rCBV. Log-rank tests were used to evaluate the association of rCBV with survival and time to progression. Kaplan-Meier time-to-progression curves were generated. Tumor volumes and CBV measurements were obtained at the initial examination and again at follow-up to determine the association of rCBV with tumor volume progression. RESULTS:Wilcoxon tests showed patients manifesting an adverse event (either death or progression) had significantly higher rCBV (P = 0.003) than did patients without adverse events (complete response or stable disease). Log-rank tests showed that rCBV exhibited a significant negative association with disease-free survival (P = 0.0015), such that low rCBV values were associated with longer time to progression. Kaplan-Meier curves demonstrated that lesions with rCBV less than 1.75 (n = 16) had a median time to progression of 4620 +/- 433 days, and lesions with rCBV more than 1.75 (n = 19) had a median time to progression of 245 +/- 62 days (P < 0.005). Lesions with low baseline rCBV (< 1.75) demonstrated stable tumor volumes when followed up over time, and lesions with high baseline rCBV (> 1.75) demonstrated progressively increasing tumor volumes over time. CONCLUSION/CONCLUSIONS:Dynamic susceptibility contrast-enhanced perfusion magnetic resonance imaging may be used to identify LGGs that are either high-grade gliomas, misdiagnosed because of sampling error at pathological examination or that have undergone angiogenesis in the progression toward malignant transformation. This suggests that rCBV measurements may be used as a second reference standard to determine the surgical management/risk-benefit equation and postsurgical adjuvant therapy for LGGs.

PURPOSE/OBJECTIVES: To identify potential factors that place patients with cancer at risk for unplanned readmissions after discharge from the hospital. DESIGN: Retrospective, descriptive, medical record review. SETTING: A National Cancer Institute-designated comprehensive cancer center in an urban area of the Northeastern United States. SAMPLE: 78 patients were selected from those readmitted within seven days of discharge. For each readmission case, a nonreadmitted patient was randomly selected and matched on discharge date and reason for prior admission. The age range was 22-87 years, men and women were equally represented, and 88% were Caucasian. METHODS: The Readmission Criteria Record was developed to collect data from medical records about factors associated with readmission, including demographics, severity of illness, support at home, symptoms, and comorbidities. MAIN RESEARCH VARIABLES: Criteria associated with readmission risk. FINDINGS: Patients who had gastrointestinal cancer, nausea within 24 hours of discharge, financial and insurance concerns, or caregiver difficulty or those who lived alone were more likely to be readmitted within seven days of discharge. Patients were more likely to be readmitted on Friday than any other day. Among readmitted patients, 48% were readmitted within one to two days postdischarge. CONCLUSIONS: Knowledge of factors that may place patients with cancer at an increased risk for readmission and subsequent implementation of appropriate interventions during hospitalization may help to decrease risk of readmission. IMPLICATIONS FOR NURSING: The factors identified provide a basis for assessment, planning, interventions, and follow-up of patients to help reduce the risk of readmission and, thus, poor outcomes

PURPOSE: To retrospectively and quantitatively analyze the acromial undersurface in three dimensions and to determine its association with impingement syndrome and rotator cuff tears. MATERIALS AND METHODS: Institutional review board approval was received with exemption of informed consent for this retrospective HIPAA-compliant study. Magnetic resonance images were evaluated in 84 patients (63 males, 21 females; mean age, 42.6 years; age range, 15-74 years). On the basis of surgical results, patients were separated into three groups: those without shoulder impingement or rotator cuff tears (31 patients), those with shoulder impingement (22 patients), and those with rotator cuff tears (31 patients). To quantitate the acromial undersurface, the structure was manually plotted, and a mathematic model was created by using splines. The undersurface was divided into a 20 x 20 grid. For each patient, a shape index (SI) data set and local undersurface angulation (LUA) data set were determined. Regression analyses were used to identify differences between groups, and prediction models were constructed on the basis of correspondent areas. RESULTS: Analysis of both data sets yielded no apparent progression between groups and demonstrated a lack of similarity between the impingement and rotator cuff tear groups. Discrimination between groups could be demonstrated by dividing the lateral portion of the acromial undersurface into contiguous blocks. The highest overall diagnostic accuracy of our prediction models was 58.3% (49 of 84) by using 10 blocks of the SI data set and 73.8% (62 of 84) by using five blocks of the LUA data set. Conclusion: Three-dimensional modeling yields objective data about the acromial undersurface. On the basis of this method, osseous impingement by the acromion is not a primary cause of shoulder impingement syndrome or rotator cuff tears

PURPOSE: To retrospectively assess the usefulness of contrast material-enhanced T1-weighted magnetic resonance (MR) imaging alone and with T2-weighted MR imaging in the diagnosis of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: A waiver of informed consent and institutional review board approval for this retrospective study were granted. The study was HIPAA compliant. Twenty-eight men (mean age, 49 years; range, 23-70 years) and 10 women (mean age, 53 years; range, 42-72 years) with cirrhosis underwent T2-weighted and contrast-enhanced T1-weighted MR imaging at 1.5 T within 90 days of liver transplantation. Three readers reviewed the T1-weighted images alone and then the T2-weighted and T1-weighted images together. Lesion detection, characterization, and reader confidence levels were recorded. RESULTS: At liver explantation, 57 lesions were present in 18 patients: 19 HCCs, 33 dysplastic nodules, and five cysts. Contrast-enhanced T1-weighted imaging depicted 13 of 19 HCCs with an overall sensitivity of 68.4% (13 of 19) and specificity of 65.7% (23 of 35). The sensitivity and specificity for detection of dysplastic nodules (sensitivity, 9%; specificity, 68.4%) and HCCs (sensitivity, 68.4%; specificity, 65.7%) were nearly identical for T1-weighted images read alone or read with T2-weighted images. The only difference was the specificity for T1-weighted images read alone (65.7%) and read with T2-weighted images (62.9%). The addition of T2-weighted images altered the diagnosis in one of 90 (1.1%) cases and provided an increase in diagnostic confidence in four of 258 (1.6%) cases for independent readers and three of 90 (3.3%) cases at consensus reading. CONCLUSION: Contrast-enhanced T1-weighted imaging can be used as a stand-alone sequence for the diagnosis of HCC in patients with cirrhosis prior to liver transplantation

PURPOSE: To retrospectively evaluate the prevalence of pterygoid process sclerosis in patients with untreated nasopharyngeal carcinoma. MATERIALS AND METHODS: This retrospective HIPAA-compliant study was performed after the institutional review board deemed it to be exempt from review and patient informed consent. Contrast material-enhanced computed tomographic (CT) scans of the neck obtained in 31 patients (22 men, nine women; mean age, 42 years; age range, 27-68 years) with untreated nasopharyngeal carcinoma and in 31 control subjects (17 men, 14 women; mean age, 43 years; age range, 19-62 years) were evaluated independently by two neuroradiologists. The presence of sclerosis of the pterygoid process-defined as increased attenuation in the medullary cavity and/or thickening of the cortical bone-was assessed. Other findings noted included pterygoid process erosion, enhancing tumor adjacent to the pterygoid process, and CT evidence of parapharyngeal extension of the tumor. The data were evaluated by using generalized estimating equations based on a binary logistic regression model. RESULTS: The prevalence of pterygoid process sclerosis averaged for the two readers was 60% (37 of 62 subjects) among the patients with nasopharyngeal carcinoma but only 3% (two of 62 subjects) among the control subjects, indicating a highly significantly increased prevalence (P < .001) of this finding in the patients with nasopharyngeal carcinoma. The overall prevalences of pterygoid process erosion, parapharyngeal extension of tumor, and enhancing tumor adjacent to the pterygoid process were 27% (17 of 62 subjects), 47% (29 of 62 subjects), and 77% (48 of 62 subjects), respectively. Pterygoid process sclerosis was the sole skull base abnormality in 36% (11 of 31) of the patients with nasopharyngeal carcinoma. CONCLUSION: Sclerosis of the pterygoid process, which was present in about half of the patients with untreated nasopharyngeal carcinoma, may reflect tumor proximity to or tumor invasion of the pterygoid process

PURPOSE: To identify, by using a chest phantom, whether vessels that contact lung nodules measuring less than 5 mm in diameter will affect nodule volume assessment. MATERIALS AND METHODS: Forty synthetic nodules (20 with ground-glass attenuation and 20 with solid attenuation) that measured less than 5 mm in diameter were placed into a chest phantom either adjacent to (n = 30) or isolated from (n = 10) synthetic vessels. Nodules were imaged by using low-dose (20 mAs) and diagnostic (120 mAs) multi-detector row computed tomography (CT). Nodules that were known to lie in direct contact with vessels were confirmed by visual inspection. Nontargeted 1.25 x 1.00-mm sections were analyzed with a three-dimensional computer-assisted method for measuring nodule volume. A mixed-model analysis of variance was used to examine the influence of several factors (eg, the presence of adjacent vessels; tube current-time product; and nodule attenuation, diameter, and location) on measurement error. RESULTS: The mean absolute error (MAE) for all nodules adjacent to vessels was 2.3 mm(3), which was higher than the MAE for isolated nodules (1.9 mm(3)) (P < .001). This difference proved significant only for diagnostic CT (2.2 mm(3) for nodules adjacent to vessels vs 1.3 mm(3) for nodules isolated from vessels) (P < .05). A larger MAE was noted for nodules with ground-glass attenuation (2.3 mm(3)) versus those with solid attenuation (2.0 mm(3)), for increasing nodule volume (1.66 mm(3) for nodules smaller than 20 mm(3) vs 2.83 mm(3) for nodules larger than 40 mm(3)), and for posterior nodule location (P < .05). CONCLUSION: The presence of a vessel led to a small yet significant increase in volume error on diagnostic-quality images. This represents less than one-third of the overall error, even for nodules larger than 40 mm(3) or approximately 4 mm in diameter. This increase, however, may be more important for smaller nodules with errors of less than 3 mm(3)

BACKGROUND AND PURPOSE: Clinical MR imaging scanners now offer many choices of hardware configurations that were not available in the first 25 years of their existence. Our goal was to assess the influence of coil technology, magnetic field strength, and echo time (TE) on the sensitivity, reflected by the signal intensity-to-noise-ratio (SNR) and reproducibility of proton MR spectroscopy (1H-MR spectroscopy). MATERIAL AND METHODS: The SNR, the intersubject reproducibility, and the intrasubject reproducibility of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) levels were compared at the common TEs of 30, 144, and 288 ms, by using 1H-MR spectroscopy in 6 volunteers at (1) 3T with a single-element quadrature (SEQ); (2) 1.5T with SEQ; and (3) 1.5T with a 12-channel phased-array (PA) head coil. RESULTS: In terms of sensitivity, the best SNR for all metabolites was obtained at the shortest TE (30 ms). It was comparable between the 3 and 1.5T with the PA, but approximately 35% better than the 1.5T with SEQ. This SNR difference declined <25% at TE of 144 ms and to equity among all imagers at TE of 288 ms. Reproducibility, reflected in the coefficient of variation (CV), was best for NAA at TE of 288 ms, 15%-50% better than at TE of 30 ms in either gray (GM) or white matter (WM). The CV for Cr was best, at TE of 288 ms for GM, but its WM results were independent of TE. Metabolite level reproducibility did not depend on coil technology or magnetic field strength. CONCLUSIONS: For the same coil type, the SNR of all major metabolites was approximately 35% better at 3T than at 1.5T. This advantage, however, was offset at 1.5T with a PA coil, making it a cost-effective upgrade for existing scanners. Surprisingly and counterintuitively, despite the lowest SNR, the best reproducibility was obtained at the longest TE (288 ms), regardless of field or coil