Axial T2-weighted Fast Spin-echo Research Articles

Spectrum of Magnetic Resonance imaging in Afebrile Pediatric Epilepsy

Background: Pediatric neurological disorders are commonly encountered. Epilepsy is one of the most common neurological disorder in childhood. Clinically diagnosis is established by two or more unprovoked seizures at least 24 hours apart. It has got considerable importance due to fact that it can cause anxiety in parents. Cortical malformations characterized by abnormal structure of cerebral cortex are one of the major cause for epilepsy. Magnetic resonance imaging is the modality of choice to evaluate the structural anomaly, the cause of seizure disorder and to assess the potential need for surgery. In this study, we tried to evaluate the spectrum of MRI imaging to evaluate afebrile pediatric epilepsy. Subjects and Methods: The study was retrospective cross sectional study. We collected data of 400 patients of pediatric epilepsy who underwent non contrast MRI evaluation during June 2017 to January 2019 at department of Radio-diagnosis at GCS Medical college, Hospital and Research Center. Exclusion criteria consist of a recent history of fever and clinical laboratory parameters of any infective cause. MRI was done using 1.5 Tesla equipment. Sequences included Sagittal T1-weighted spin echo (SE), Axial T2-weighted fast spin echo (FSE), Coronal oblique fast fluid attenuated inversion recovery (FLAIR), Axial diffusion weighted single-shot spin-echo echoplanar, Axial 3D inversion recovery prepped fast SPGR (spoiled gradient recalled). Results: The most common detected changes were unilateral and bilateral mesial temporal sclerosis (21% & 9% respectively), cortical dysplasia (1.5%), migrational anomalies, neurocutaneous syndromes and few cortical neoplasms (0.5 to 1%). Conclusion: MRI in today's world plays a deciding role in diagnostic work-up of a child with epilepsy.

Prediction of Vestibular Imbalance in Acute Peripheral Vestibulopathy by Measuring Horizontal Ocular Deviation on Magnetic Resonance Imaging.

The aim of the study is to evaluate whether horizontal ocular deviation (OD) from MR imaging in the emergency room (ER) reflects vestibular imbalance, by comparing the horizontal OD in patients with acute vestibulopathy to controls. Retrospective review. A total of 69 patients with acute unilateral peripheral vestibulopathy and 30 healthy subjects were included. Horizontal OD was quantified by using the axial T2-weighted fast-spin echo (FSE) images of the brain at 1.5 T. In the study group, the results of VFTs (videonystagmography [VNG], caloric test, rotary chair test, and cervical vestibular evoked myogenic potentials [cVEMP]) were also reviewed. The averaged angle of right and left horizontal ODs was compared between patients with acute unilateral vestibulopathy and healthy controls. Also, the correlation between horizontal OD and results of VFTs was analyzed in the study group. The averaged angle of horizontal OD in study group (23.7° ± 11.6°) was significantly greater than that of control group (4.27° ± 3.7°) (p < 0.05). Horizontal OD significantly correlated with slow phase velocity of spontaneous nystagmus (SN), the value of caloric paresis (CP) on caloric testing, rotary chair gain, asymmetry ratio of rotary chair test and interaural difference (IAD) of cVEMP, regardless of time intervals between magnetic resonance imaging (MRI) and VFTs. Horizontal OD significantly correlated with parameters of VFT which reflect the vestibular imbalance. Therefore, horizontal OD can be used as an indicator of unilateral peripheral vestibular weakness.

Can magnetic resonance imaging be an alternative to computed tomography in immunocompromised patients with suspected fungal infections? Feasibility of a speed optimized examination protocol at 3 Tesla

ObjectiveTo prospectively evaluate a short MRI examination protocol for the detection of nodular pulmonary infiltrates in immunocompromised patients with hematologic diseases and suspected invasive fungal infections. MethodsPatients with nodular infiltrates on CT scans were examined on a 3T MRI scanner. The standardized protocol included axial T2-weighted fast spin echo (FSE) sequences +/− fat saturation (FS), and axial T1-weighted gradient echo (GRE) sequences. Long and short axis diameters of nodular infiltrates and visibility were assessed on MR images at least six months after the CT scan, blinded to patient and examination data. Inter- and intra-reader reliability was assessed in two patients. Statistical testing included Wilcoxon-test, Cohen’s kappa, and intra-class correlation coefficients. Bland-Altman plots were created to visualize differences in the measurements. ResultsIn all 13 patients MRI examinations were completed successfully (average examination time 12min and maximum breath-hold time of 8s). CT detected 409 nodules. Sensitivity of MRI was 93.2% when using all sequences in combination; considering nodules >5mm, sensitivity increased to 97.9%. Reliability analysis showed excellent correlations with an intra-class correlation coefficient of at least 0.89 for T2 FSE (95% CI 0.79–0.93, p<0.01) images for the intra-, and the lowest of 0.77 for T2 FSE (95% CI 0.55–0.89, p<0.01) images for the inter-reader comparison. Agreement on nodule visibility was at least kappa=0.95 (p<0.01) for the intra- and 0.72 (p<0.01) for the inter-reader analysis. ConclusionWith an average examination time of 12min, pulmonary MRI at 3T is feasible in immunocompromised patients with hematologic diseases and suspected invasive fungal infections. MRI might serve as an alternative diagnostic tool during follow-up examinations.

Comparison of MERGE and Axial T2-Weighted Fast Spin-Echo Sequences for Detection of Multiple Sclerosis Lesions in the Cervical Spinal Cord

The purpose of our study was to compare axial multiple-echo recombined gradient echo (MERGE) with axial T2-weighted fast spin-echo (FSE) imaging for the detection of multiple sclerosis (MS) lesions in the cervical spinal cord on MRI. Twenty-nine cervical spine MRI studies of patients with MS lesions and 29 control cases were reviewed retrospectively. Two blinded neuroradiologists independently assessed randomized axial MERGE and axial T2-weighted FSE sequences from each study, documenting the location and number of cord lesions, the degree of confidence in calling each lesion, and the presence of artifacts. The reference standard was determined by an unblinded consensus review of all sequences performed for each case, with lesions considered present if detected on two or more sequences. Lesion detection rates and conspicuity, false-positive findings, and reader confidence and artifact scores were compared for the sequences, and interreader agreement was assessed. Eighty-three lesions were assessed. The mean true-positive lesion detection rate was 87% (95% CI, 79-93%) with MERGE and 67% (60-75%) with T2-weighted FSE, with interreader positive agreement scores of 74% and 75%, respectively. A greater number of false-positive findings were seen with MERGE for both the MS and control cases. Average confidence and artifact scores were similar for both sequences. Subjectively, lesions were more conspicuous in 21 cases with MERGE and four cases with T2-weighted FSE and were equally conspicuous in four cases. MERGE and T2-weighted FSE sequences are complementary. MERGE provided greater sensitivity for cord lesions whereas axial T2-weighted FSE provided improved lesion specificity. Further investigation is required to assess the clinical impact of MERGE in the diagnosis and management of MS.

Dual-Source Parallel Radiofrequency Excitation Body MR Imaging Compared with Standard MR Imaging at 3.0 T: Initial Clinical Experience

To prospectively compare the image quality and homogeneity of magnetic resonance (MR) images obtained by using a dual-source parallel radiofrequency (RF) excitation body MR imaging system with parallel transmission and independent RF shimming with the image quality and homogeneity of single-source MR images obtained by using standard sequences for routine clinical use in patients at 3.0 T. After institutional review board approval and informed patient consent were obtained, a dual-source parallel RF excitation 3.0-T MR system with independent RF shimming and parallel transmission technology was used to examine 28 patients and was compared with a standard 3.0-T MR system with single RF transmission. The RF power was distributed to the independent ports of the system body coil by using two RF transmission sources with full software control, enabling independent control of the phase and amplitude of the RF waveforms. Axial T2-weighted fast spin-echo (SE) and diffusion-weighted (DW) liver images, axial T2-weighted fast SE pelvic images, and sagittal T1- and T2-weighted fast SE spinal images were obtained by using dual- and single-source RF excitation. Two radiologists independently evaluated the images for homogeneity and image quality. Statistical significance was calculated by using the nonparametric Wilcoxon signed rank test. Interobserver agreement was determined by using Cohen kappa and Kendall tau-b tests. Image quality comparisons revealed significantly better results with dual-source rather than single-source RF excitation at T2-weighted liver MR imaging (P = .001, kappa = 1.00) and better results at DW liver imaging at a statistical trend level (P = .066, tau-b > 0.7). Owing to reduced local energy deposition, fewer acquisitions and shorter repetition times could be implemented with dual-source RF excitation pelvic and spinal MR imaging, with image acquisition accelerating by 18%, 33%, and 50% compared with the acquisitions with single-source RF excitation. Image quality did not differ significantly between the two MR techniques (P > .05, tau-b > 0.5). Dual-source parallel RF excitation body MR imaging enables reduced dielectric shading, improved homogeneity of the RF magnetic induction field, and accelerated imaging at 3.0 T.

Renal angiomyolipoma with pseudocapsule mimicking renal cell carcinoma

We present a case of renal angiomyolipoma with pseudocapsule mimicking renal cell carcinoma. Axial in-phase and opposed-phase gradient-echo magnetic resonance (MR) images showed that the signal intensity of the lesion is hypointense on the opposed-phase image compared with that on the in-phase image, confirming the presence of lipid in the lesion. Axial T2-weighted fast spin–echo MR imaging showed the lesion as slightly hyperintense relative to adjacent renal parenchyma. On T2-weighted MR imaging, a hypointense rim surrounded the lesion.

Detection of hepatocellular carcinoma (HCC) using super paramagnetic iron oxide (SPIO)‐enhanced MRI: Added value of diffusion‐weighted imaging (DWI)

To evaluate whether diffusion-weighted imaging (DWI) improves the detection of hepatocellular carcinoma (HCC) on super paramagnetic iron oxide (SPIO)-enhanced MRI. This retrospective study group consisted of 30 patients with 50 HCC nodules who underwent MRI at 1.5 Tesla. Two combined MR sequence sets were compared for detecting HCC: SPIO-enhanced MRI (axial T2-weighted fast spin-echo (FSE) and T1-/T2*-weighted fast field echo (FFE) scanned before and after administration of ferucarbotran) and SPIO-enhanced MRI + DWI (SPIO-enhanced MRI with axial DWI scanned before and after administration of ferucarbotran). Three blinded readers independently reviewed for the presence of HCC on a segment-by-segment basis using a four-point confidence scale. The performance of the two combined MR sequence sets was evaluated using receiver operating characteristic (ROC) analysis. The average area under the ROC curve (Az) of the three readers for the SPIO-enhanced MRI + DWI set (0.870 +/- 0.046) was significantly higher that that for the SPIO-enhanced MRI set (0.820 +/- 0.055) (P = .025). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detection of HCC were 66.0%, 98.0%, 90.0%, and 91.4%, respectively, for the SPIO-enhanced MRI set, and 70.0%, 98.6%, 92.9%, and 92.4%, respectively, for the SPIO-enhanced MRI + DWI set. The SPIO-enhanced MRI + DWI set outperformed the SPIO-enhanced MRI set for depicting HCC.

SAI-24: Longitudinal study of lipid-modifying therapies on carotid atherosclerotic plaque morphology in vivo using magnetic resonance imaging

We hypothesize that high-resolution magnetic resonance imaging (MRI) in vivo can accurately quantify carotid plaque volume and differentiate carotid plaque elements that are related to ischemic events. A randomized, placebo-controlled pilot study in patients with clinically stable carotid atherosclerosis (n = 60) is currently underway using quantitative micro-MRI techniques to determine the effect of aggressive low-density lipoprotein (LDL) lowering (simvastatin 80 mg), moderate LDL lowering (simvastatin 10 mg), and LDL lowering with high-density lipoprotein elevation (simvastatin 20 mg and Niaspan [extended-release niacin; Kos Pharmaceuticals, Inc., Miami, FL] 2,000 mg) on MRI plaque characteristics over 12 months. MRI (1.5 T) consisted of 3D time-of-flight magnetic resonance angiography of the carotid bifurcation, axial T1-weighted spin echo, axial proton density fast spin echo (FSE), and axial T2-weighted FSE at the level of the bifurcation (approximately ± 1.6 cm). Total plaque volume was estimated from computer-assisted measurement of plaque cross-sectional area plaque area × slice thickness × number of slices (typically 2.0 mm × 16 slices). The intraclass correlation coefficient for plaque volume from repeat baseline scans (n = 8) was 0.95 using fat-suppressed proton density FSE images. In these patients, plaque volume was estimated at 1.34 ± 0.38 cm3 (mean ± SD). Plaque calcification, fibrous tissue content, lipid content, and hemorrhage are currently being estimated using the multiparametric imaging data. The effect of treatment on MRI indices will be correlated with changes in lipoproteins, serum inflammatory markers and urinary isoprostanes, indices of oxidant stress in vivo. Noninvasive micro-MRI techniques applied to carotid atherosclerosis in humans in vivo offers the potential to assess the longitudinal effect of therapies on quantitative indices of plaque morphology.

Case of the season

A THIRTY-FIVE-YEAR-OLD woman presented with a 3-month history of progressive dysesthesia of her feet, unsteadiness in the gait, and generalized weakness. There was no history of any surgery or drug intake. On examination, there was moderate pallor. Fine touch, position, and vibration sense were impaired below the anterior superior iliac spines. Romberg's sign was positive. There was mildly reduced motor power (4/5) in both lower limbs. Deep tendon reflexes of lower limbs were exaggerated. Plantars were equivocal. Laboratory tests revealed macrocytic anemia with hemoglobin of 8.6 g/dL, elevated mean corpuscular volume (117 fl), hypersegmented neutrophils, low serum cobalamin (<100 pg/mL), and elevated serum folate levels (22 ng/mL). Magnetic resonance imaging (MRI) of the spine was performed. Figure 1 is a sagittal T2-weighted fast spin-echo (FSE) image showing an abnormal increased signal intensity of the dorsal and lower cervical spinal cord. Figure 2 is an axial T2weighted FSE image at the upper dorsal region showing that the signal abnormality is located in the posterior columns of the spinal cord. Barium meal gastrointestinal series was normal.

Annular tears and disk herniation: prevalence and contrast enhancement on MR images in the absence of low back pain or sciatica.

To evaluate the prevalence and radiologic findings of annular tear (especially of contrast material enhancement), bulging disk, and disk herniation on T2-weighted and gadolinium-enhanced T1-weighted magnetic resonance (MR) images in people without low back pain (LBP) or sciatica. Thirty-six volunteers without LBP and/or sciatica (18 with no symptoms in their lifetime and 18 who were pain free for at least 6 months) were examined with sagittal and axial T2-weighted fast spin-echo (SE) and sagittal gadolinium-enhanced T1-weighted fast SE imaging. The prevalence and MR findings of bulging disk, focal protrusion, extrusion, and nonenhancing or enhancing annular tears were assessed. The prevalence of bulging disk and focal disk protrusion was 81% (29 volunteers) and 33% (12 volunteers), respectively. There were no extrusions. Twenty-eight annular tears were found in 20 patients (56%); 27 tears (96%) also showed contrast enhancement. Annular tears and focal disk protrusions on MR images, with or without contrast enhancement, are frequently found in an asymptomatic population. Extruded disk herniation, displacement of nerve root, and interruption of annuloligamentous complex are unusual findings in an asymptomatic population and can be more closely related to patients with LBP or sciatica.