MR imaging evaluation of inferior olivary nuclei: comparison of postoperative subjects with and without posterior fossa syndrome.

BACKGROUND AND PURPOSE: Posterior fossa syndrome is a severe postoperative complication occurring in up to 29% of children undergoing posterior fossa tumor resection; it is most likely caused by bilateral damage to the proximal efferent cerebellar pathways, whose fibers contribute to the Guillain-Mollaret triangle. When the triangle is disrupted, hypertrophic olivary degeneration develops. We hypothesized that MR imaging patterns of inferior olivary nucleus changes reflect patterns of damage to the proximal efferent cerebellar pathways and show association with clinical findings, in particular the presence or absence of posterior fossa syndrome. MATERIALS AND METHODS: We performed blinded, randomized longitudinal MR imaging analyses of the inferior olivary nuclei of 12 children with and 12 without posterior fossa syndrome after surgery for midline intraventricular tumor in the posterior fossa. The Fisher exact test was performed to investigate the association between posterior fossa syndrome and hypertrophic olivary degeneration on MR imaging. The sensitivity and specificity of MR imaging findings of bilateral hypertrophic olivary degeneration for posterior fossa syndrome were measured. RESULTS: Of the 12 patients with posterior fossa syndrome, 9 had bilateral inferior olivary nucleus abnormalities. The 12 patients without posterior fossa syndrome had either unilateral or no inferior olivary nucleus abnormalities. The association of posterior fossa syndrome and hypertrophic olivary degeneration was statistically significant (P < .0001). CONCLUSIONS: Hypertrophic olivary degeneration may be a surrogate imaging indicator for damage to the contralateral proximal efferent cerebellar pathway. In the appropriate clinical setting, bilateral hypertrophic olivary degeneration may be a sensitive and specific indicator of posterior fossa syndrome.

Correlation between cerebral blood volume measurements by perfusion-weighted magnetic resonance imaging and two-year progression-free survival in gliomas.

Our goal was to determine whether relative cerebral blood volume (rCBV) can serve as an adjunct to histopathologic grading in the assessment of gliomas, with the hypothesis that rCBV can predict two-year survival. We evaluated 29 newly diagnosed gliomas (13 WHO grade II, seven grade III, nine grade IV; 17 astrocytomas, 12 oligodendroglial tumors). Dynamic susceptibility-weighted contrast-enhanced perfusion MR images and CBV maps were obtained. rCBVmax measurements (maximum tumor CBV/contralateral normal tissue CBV) and progression-free survival (PFS) were recorded. Receiver operating characteristic curves and Kaplan-Meier survival curves were calculated for rCBVmax and histologic grade. rCBVmax measurements differed between gliomas without (2.38 +/- 1.22) and with progression (5.57 +/- 2.84) over two years. The optimal rCBVmax cut-off value to predict progression was 2.95. rCBVmax < 2.95 was a significant predictor of two-year PFS, almost as accurate as WHO grade II. In the pure astrocytoma subgroup, the optimal rCBVmax cut-off value to predict progression was 2.85. In this group rCBVmax < 2.85 was a significant predictor of two-year PFS, an even better predictor of two-year PFS than WHO grade II. rCBVmax can be used to predict two-year PFS in patients with gliomas, independent of pathologic findings, especially in tumors without oligodendroglial components.

Clinical pitfalls related to short and long echo times in cerebral MR spectroscopy.

MR-spectroscopy (MRS) is a multiparameter diagnostic tool and modification of each parameter results in spectrum morphology changes. In particular, changing the echo time (TE) represents a useful tool to highlight different diagnostic elements, but also has significant impact on the spectrum morphology. Diagnostic errors can result if the role of TE is not properly considered. This article reviews the four most common TE-related pitfalls of MRS interpretation. Clinical practical methods to avoid such pitfalls are also suggested.

Comparison of gadobenate dimeglumine and gadodiamide in the evaluation of spinal vascular anatomy with MR angiography.

BACKGROUND AND PURPOSE: Spinal MRA has been increasingly used to evaluate non-invasively the spinal cord vasculature. Our aim was to prospectively compare gadobenate dimeglumine with gadodiamide in the assessment of the normal spinal cord vasculature by using contrast-enhanced MRA, with the hypothesis that high T1 relaxivity gadolinium compounds may improve visualization of the intradural vessels. MATERIALS AND METHODS: Twenty subjects underwent 2 temporally separated contrast-enhanced spinal MRAs with gadobenate dimeglumine and gadodiamide (0.2 mmol/kg). Two blinded observers rated postprocessed images on the following qualitative parameters: background homogeneity, sharpness, vascular continuity, and contrast enhancement. Delineation of the ASA, AKA, hairpin configuration of the ASA-AKA connection, and visualized ASA length were recorded. Each observer indicated which of the 2 matched studies he or she thought was of the best overall diagnostic quality. RESULTS: According to both observers gadobenate dimeglumine was superior to gadodiamide in the representation of vascular continuity and contrast (P value < .05). Background homogeneity was not significantly different between the studies. One observer favored gadobenate dimeglumine over gadodiamide in the demonstration of vascular sharpness, while the second observer did not find any significant difference between contrast agents. There was no significant difference between contrast agents in the visualization of the ASA, AKA, hairpin-shaped ASA-AKA connection, and visualized length of the ASA. The overall quality of the gadobenate dimeglumine-enhanced MRA was deemed superior in 15 and 16 cases, respectively, by the 2 observers. CONCLUSIONS: Improved image quality and vascular contrast enhancement of spinal MRA at 1.5T is achieved with high T1 relaxivity gadolinium contrast agents compared with conventional agents at equivalent doses.

Perfusion CT in squamous cell carcinoma of the upper aerodigestive tract: long-term predictive value of baseline perfusion CT measurements.

BACKGROUND AND PURPOSE: PCT studies hold short-term predictive value in patients treated with chemoradiotherapy. Our aim was to examine the long-term predictive value of baseline PCT studies for local tumor control and overall survival in SCCA of the upper aerodigestive tract treated with chemoradiotherapy. MATERIALS AND METHODS: Eighty-four patients with advanced SCCA underwent PCT followed by concomitant chemoradiation. The acquired perfusion maps represented BF, BV, MTT, and PS. Visual analysis of the parametric maps for identification of tumor perfusion patterns was conducted. ROC curves, t tests, and Kaplan-Meier survival curves were plotted for local disease control and overall survival. RESULTS: The median time of local tumor control was 24 months. The BF and PS values were significantly higher in patients who had no recurrence than in those with local failure (P < or = .02). The BF and PS were predictive (P < or = .0006) but BV and MTT held no significant predictive values for local tumor control. The patients with high BF and PS had a longer local tumor control than the patients with hypoperfused tumors (P = .0007). A visually detected BF-BV mismatch had a sensitivity/specificity of 63%/66% (P = .03) and 59%/69% (P = .03) for local tumor control and OS, respectively. Patients without mismatch lived significantly longer than patients with mismatch (P = .01). CONCLUSIONS: BF, PS, and mismatch of BF-BV are significant predictors of local tumor control after chemoradiation in SCCA of the upper aerodigestive tract.

Changes in perfusion CT of advanced squamous cell carcinoma of the head and neck treated during the course of concomitant chemoradiotherapy.

BACKGROUND AND PURPOSE: Concomitant chemoradiation is a promising therapy for the treatment of locoregionally advanced head and neck carcinoma. The purpose of this study was to prospectively evaluate early changes in primary tumor perfusion parameters during concomitant cisplatin-based chemoradiotherapy of locoregionally advanced SCCHN and to evaluate their predictive value for response of the primary tumor to therapy. MATERIALS AND METHODS: Twenty patients with locoregionally advanced SCCHN underwent perfusion CT scans before therapy and after completion of 40 Gy and 70 Gy of chemoradiotherapy. BF, BV, MTT, and PS of primary tumors were quantified. Differences in perfusion and tumor volume values during the therapy as well as between responders and nonresponders were analyzed, and ROC curves were used to assess predictive value of the baseline and follow-up functional parameters. RESULTS: The tumor volumes at 40 Gy and at 70 Gy were significantly lower compared with baseline values (P = .014 and P = .007). In the 6 nonresponders, measurements after 40 Gy showed a nonsignificant trend of increased BF, BV, and PS values compared with the baseline values (P = .06). In 14 responders, a significant reduction of BF values was recorded after 40 Gy (P = .04) and after 70 Gy (P = .01). In responders, BV values showed a reduction after 40 Gy followed by a plateau after 70 Gy (P = .04), whereas in nonresponders there was a nonsignificant elevation of the BV. Baseline BV predicted short-term tumor response with a sensitivity of 60% and specificity of 100% (P = .01). After completion of 40 Gy of concomitant chemoradiation BV was a more significant predictor than were BF and MTT. CONCLUSIONS: The results suggest that in advanced SCCHN the perfusion CT monitoring might be of predictive value for identifying tumors that may respond to cisplatin-based chemoradiotherapy.

Review of portable CT with assessment of a dedicated head CT scanner.

This article reviews a number of portable CT scanners for clinical imaging. These include the CereTom, Tomoscan, xCAT ENT, and OTOscan. The Tomoscan scanner consists of a gantry with multisection detectors and a detachable table. It can perform a full-body scanning, or the gantry can be used without the table to scan the head. The xCAT ENT is a conebeam CT scanner that is intended for intraoperative scanning of cranial bones and sinuses. The OTOscan is a multisection CT scanner intended for imaging in ear, nose, and throat settings and can be used to assess bone and soft tissue of the head. We also specifically evaluated the technical and clinical performance of the CereTom, a scanner designed specifically for neuroradiologic head imaging. The contrast performance of this scanner permitted the detection of 4-mm low-contrast lesions, and the limiting spatial resolution was 7 line pairs per centimeter. The measured volume of the CT dose index (CTDI(vol)) for a standard head CT scan was 41 mGy (120 kV/14 mAs). All clinical images were of diagnostic quality, and the average patient effective dose was 1.7 mSv. We conclude that the CereTom portable CT scanner generates satisfactory clinical images at acceptable patient doses.

Response and progression-free survival in oropharynx squamous cell carcinoma assessed by pretreatment perfusion CT: comparison with tumor volume measurements.

BACKGROUND AND PURPOSE: Perfusion CT (PCT) provides a rapid, reliable, and non-invasive technique for assessing tumor vascularity. The purpose of this study was to assess whether pretreatment dynamic perfusion CT (PCT) may predict response to induction chemotherapy and midterm progression-free survival (PFS) in advanced oropharynx squamous cell carcinoma (SCCA) and to compare the results with those derived by tumor volume measurements. MATERIALS AND METHODS: Nineteen patients underwent routine contrast-enhanced CT (CECT), pretreatment PCT, and conventional endoscopy. Tumor response was determined according to radiologic (RECIST) criteria. The PCT parameters, tumor volume, radiologic response, and PFS were analyzed with use of Cox-proportional hazards model, receiver operating characteristic (ROC), and Kaplan-Meier analysis. RESULTS: The baseline blood flow (BF), blood volume (BV), and permeability surface area product (PS) were significantly higher, whereas mean transit time (MTT) was significantly lower in the responders than in the nonresponders (P < or = .002). BV showed 100% sensitivity, MTT and PS had the highest specificity (100%), and BF showed 84.2% sensitivity and 66.7% specificity for prediction of tumor response after induction chemotherapy. The pretreatment tumor volume correlated with PFS in the pooled patients group (r = 0.4; P < .0001), whereas postinduction tumor volume correlated significantly with PFS in the responders and nonresponders (r = 0.22-0.64; P < or = .006). Pretreatment tumor volume (P = .0001) and BF (P = .001) were significant predictors for PFS. CONCLUSIONS: Pretreatment PCT parameters may predict response after induction chemotherapy. Tumor volume and BF values may predict PFS in patients with advanced oropharyngeal SCCA.

Cerebral blood volume measurements by perfusion-weighted MR imaging in gliomas: ready for prime time in predicting short-term outcome and recurrent disease?

BACKGROUND AND PURPOSE: Current classification and grading of primary brain tumors has significant limitations. Our aim was to determine whether the relative cerebral volume (rCBV) measurements in gliomas may serve as an adjunct to histopathologic grading, with a hypothesis that rCBV values are more accurate in predicting 1-year survival and recurrence. MATERIALS AND METHODS: Thirty-four patients with gliomas (WHO grade I-IV, 27 astrocytomas, 7 tumors with oligodendroglial components) underwent contrast-enhanced MR rCBV measurements before treatment. The region of interest and the single pixel with the maximum CBV value within the tumors were normalized relative to the contralateral normal tissue (rCBV(mean) and rCBV(max), respectively). Karnofsky performance score and progression-free survival (PFS) were recorded. Receiver operating characteristic curves and Kaplan-Meier survival analysis were conducted for CBV and histologic grade (WHO grade). RESULTS: Significant correlations were detected only when patients with oligodendrogliomas and oligoastrocytomas were excluded. The rCBV(mean) and rCBV(max) in the astrocytomas were 3.5 +/- 2.9 and 3.7 +/- 2.7. PFS correlated with rCBV parameters (r = -0.54 to -0.56, P < or = .009). WHO grade correlated with rCBV values (r = 0.65, P < or = .0002). rCBV(max) > 4.2 was found to be a significant cutoff value for recurrence prediction with 77.8% sensitivity and 94.4% specificity (P = .0001). rCBV(max) < or = 3.8 was a significant predictor for 1-year survival (93.7% sensitivity, 72.7% specificity, P = .0002). The relative risk for shorter PFS was 11.1 times higher for rCBV(max) > 4.2 (P = .0006) and 6.7 times higher for WHO grade > II (P = .05). The combined CBV-WHO grade classification enhanced the predictive value for recurrence/progression (P < .0001). CONCLUSIONS: rCBV values in astrocytomas but not tumors with oligodendroglial components are predictive for recurrence and 1-year survival and may be more accurate than histopathologic grading.

The effect of statin pretreatment on infarct volume in ischemic stroke.

BACKGROUND: Treatment with statins reduces infarct volume in animal models of ischemic stroke, independently of the effect on cholesterol. This study examined this effect in humans by testing whether patients taking statins at onset of ischemic stroke had smaller infarct volumes than those not taking statins. METHODS: The study design was a retrospective cohort analysis of all verified ischemic stroke patients admitted to the Medical University of South Carolina Hospital, in 2002-2006, with magnetic resonance diffusion-weighted imaging (DWI). Patients were grouped according to statin status at admission and compared relative to infarct volume, calculated (blinded to statin status) from DWI. RESULTS: A smaller than median infarct volume following ischemic stroke was associated with the interaction of statin pretreatment and positive diabetes status. This association remained significant (p = 0.01) in multivariable analysis even after controlling for factors related to demographics, comorbidities and risk factors, clinical features on admission, use of other medications and stroke features. CONCLUSIONS: Among ischemic stroke patients in this study, infarct volume below the median was significantly associated with statin pretreatment among those with diabetes.

Whole-tumor perfusion CT parameters and glucose metabolism measurements in head and neck squamous cell carcinomas: a pilot study using combined positron-emission tomography/CT imaging.

BACKGROUND AND PURPOSE: Previous (separately performed) perfusion CT (PCT) and PET studies have been inconclusive regarding the correlation of functional tumor characteristics. The purpose of this study was to perform dual assessment of head and neck squamous cell carcinomas (SCCAs) to examine the relationship between perfusion measurements derived from PCT and glucose standardized uptake values (SUV). MATERIALS AND METHODS: We prospectively evaluated 15 primary and recurrent SCCAs using combined positron-emission tomography (PET) and CT of the head and neck. SUV(mean), SUV(max), blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability (PS) values were calculated with use of manually drawn regions of interest (ROIs) over the lesions and the healthy muscle tissue. Parametric comparison test, correlation coefficients, and regression analysis were performed. RESULTS: The mean (+/- SD) SUV(mean), SUV(max), BF, BV, MTT, and PS values in the tumor tissue were 6.26 (+/- 1.48), 15.25 (+/- 3.81), 91.50 (+/- 24.69), 5.08 (+/- 1.17), 7.51 (+/- 2.24), and 23.08 (+/- 8.77), respectively. All PET/CT and PCT parameters of muscle versus tumor tissue were statistically different (.0001 < P < .001). There were significant correlations between BF and SUV(max) as well as SUV(mean) (r = 0.57; P = .02 and r = 0.63; P = .011, respectively) in the tumors. Significant correlation was also found between PS and SUV(mean) (r = 0.53; P = .04) in the tumors. Regression analysis showed: SUV(max) = 0.09 x BF + 7.2 (R(2) = 0.33; P = .02), SUV(mean) = 0.05 x BF + 2.22 (R(2) = 0.45; P = .011), and SUV(mean) = 0.05 x PS + 5.36 (R(2) = 0.35; P = .04). The tumor to nontumor (muscle) SUV(mean) and SUV(max) ratio was 9.45 (+/- 3.55) and 17.58 (+/- 4.32), respectively. BF-ratio SUV(mean) and BF-ratio SUV(max) showed significant correlations (r = 0.64; P = .01 and r = 0.53; P = .04, respectively). Regression analysis showed ratio SUV(mean) = 0.14 x BF-3.48 (R(2) = 0.42; P = .01) and ratio SUV(max) = 0.14 x BF + 4.51 (R(2) = 0.29; P = .04). CONCLUSION: Tissue perfusion-metabolic coupling is evident in head and neck SCCAs and may provide additional diagnostic information in patients undergoing PET/CT studies.

Reproducibility, interrater agreement, and age-related changes of fractional anisotropy measures at 3T in healthy subjects: effect of the applied b-value.

BACKGROUND AND PURPOSE: There is no reproducibility study of fractional anisotropy (FA) measurements at 3T using regions of interest (ROIs). Our purpose was to establish the extent and statistical significance of the interrater variability, the variability observed with 2 different b-values, and in 2 separate scanning sessions. MATERIALS AND METHODS: Twelve healthy volunteers underwent MR imaging twice. MR imaging was performed on a 3T unit, and FA maps were analyzed independently by 2 observers using ROIs positioned in the corpus callosum, internal capsules, corticospinal tracts, and right thalamus. Changes in FA values (x10(3)) measured with 2 b-values (700 and 1000 s/mm(2)), age-related differences, interobserver agreement, and measurement reproducibility were assessed. RESULTS: In the right internal capsule genu (FA = 702/728; b = 1000/700 s/mm(2)) and the left anterior limb of the internal capsule (AIC; FA = 617/745; b = 1000/700 s/mm(2)), the FA values were significantly different between the 2 b-values (P = .02 and .05, respectively). Significant age-related differences in FA were observed in the genu of the corpus callosum and in the left AIC. Interrater measurements showed fair-to-moderate agreement for most anatomic structures. The lowest significant change for a single subject regarding any FA values between the 2 sessions was in the corpus callosum (4%), whereas the highest one was in the corticospinal tracts (27%). The Bland-Altman plot analysis showed that the 1000-s/mm(2) b-value gave satisfactorily reproducible measurements equally good or better than the 700-s/mm(2) b-value. CONCLUSION: The reproducibility of FA estimates using ROIs was satisfactory. Measurements with a b-value at 1000 s/mm(2) showed superior reproducibility in most anatomic locations.

Atypical cystic meningioma of the trigeminal nerve in a pediatric patient.

SUMMARY: We report an unusual case of atypical cystic meningioma of the trigeminal nerve proved by histology in a 15-year-old white girl. A review of the literature showed that this is only the second reported case of a meningioma of the trigeminal nerve without dural attachment and the first occurrence in a pediatric patient.

Idiopathic hypertrophic spinal pachymeningitis: report of two cases with typical MR imaging findings.

SUMMARY: Two patients with a chronic progressive myelopathy were successfully surgically treated and idiopathic hypertrophic spinal pachymeningitis (IHSP) was found on histology. In both patients, an extensive extramedullary mass of low T2 signal with peripheral contrast enhancement was compressing the spinal cord on MR imaging. This imaging appearance in patients with chronic progressive myelopathy should suggest the diagnosis of IHSP.

Apparent diffusion coefficients for differentiation of cerebellar tumors in children.

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps provide information at MR imaging that may reflect cell attenuation and integrity. We hypothesized that cerebellar tumors in children can be differentiated by their ADC values. METHODS: Brain MR imaging studies that included ADC maps were retrospectively reviewed in 32 patients with histologically proved cerebellar neoplasm. There were 17 juvenile pilocytic astrocytomas (JPA), 8 medulloblastomas, 5 ependymomas, and 2 rhabdoid (atypical teratoid/rhabdoid tumor [AT/RT]) tumors. Absolute ADC values of contrast-enhancing solid tumor regions and ADC ratios (ADC of solid tumor to ADC of normal-appearing white matter) were compared with the histologic diagnosis. ADC values and ratios of JPAs, medulloblastomas, and ependymomas were compared by using a 2-tailed t test and one-way analysis of variance (ANOVA). RESULTS: ADC values were significantly higher in pilocytic astrocytomas (1.65 +/- 0.27) (mean +/- SD) than in ependymomas (1.10 +/- 0.11) (P = .0003) and medulloblastomas (0.66 +/- 0.15) (P < .0001). Ependymomas demonstrated significantly higher ADC values than medulloblastomas (P = .0005). The observed differences were statistically significant on ANOVA (P < .001). ADC ratios were also significantly different among these 3 tumor types. AT/RT ADC values were similar to medulloblastoma. The range of ADC values and ratios within JPAs and ependymomas did not overlap with that of medulloblastomas. CONCLUSION: Assessment of ADC values of enhancing solid tumor is a simple and reliable technique for preoperative differentiation of cerebellar tumors in pediatric patients. Our cutoff values of >1.4 x 10(3) mm(2)/s for JPA and <0.9 x 10(3) mm(2)/s for medulloblastoma were 100% specific.

Imaging of oral cavity cancer.

Despite many advances in surgical techniques, technology, radiation therapy, and chemotherapy, survival rates for head and neck cancer (HNCa) have not improved significantly in decades, with many patients being diagnosed at advanced disease stages. Adequate assessment of oral cavity malignancies is critical for appropriate planning of surgical, radiation, and chemotherapy treatment. Imaging modalities used to evaluate the oral cavity include plain radiography (panoramic radiography and intraoral radiography), nuclear medicine scintigraphy, ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET). This review describes these imaging techniques and their utility, primarily CT and MRI.

Primary sellar esthesioneuroblastoma.

We describe an extremely rare case of a primary intrasellar esthesioneuroblastoma.