Temporal lobe changes following radiation therapy: imaging and proton MR spectroscopic findings

Radiation therapy for nasopharyngeal carcinoma affects the temporal lobes. This paper characterizes proton MR spectroscopic findings of the temporal lobes and correlates them with imaging changes. Single-voxel proton MR spectroscopic examinations were acquired from 13 healthy adult volunteers (25 spectra) and 18 patients (28 spectra). All patients had biopsy-confirmed nasopharyngeal carcinoma and were previously treated with radiation therapy. Six patients (33 %) had a single treatment and12 (67 %) patients had two treatments. Point resolved spectroscopy (PRESS) method was used (TR = 3000 ms, TE = 135 ms) and data processed automatically using the LCModel software package for metabolite quantification. Voxel size and geometry were adapted to the lesion to reduce skull-base lipid contamination. The metabolites were quantitated relative to water signal. For each location, an additional non-water-suppressed reference scan in fully relaxed conditions was performed. The imaging findings were divided into four categories: I, normal; II, edema only; III, contrast-enhancing lesions; and IV, cystic encephalomalacia. The N-acetyl-aspartate levels were reduced in 27 (96 %) spectra. Choline was increased in 3 (11 %), normal in 4 (14 %), and reduced in 21 (75 %) spectra. The creatine level was normal in 8 (29 %) spectra and reduced in 20 (71 %) spectra. Imaging showed 4 (14 %) spectra with category-I imaging findings; 5 (18 %) spectra with category-II findings; 15 (54 %) spectra with category-III findings; and 4 (14 %) spectra with category-IV findings. Magnetic resonance spectroscopy showed reduced N-acetyl-aspartate in radiation-induced temporal lobe changes. Creatine levels were relatively more stable. Choline levels may be increased, normal, or reduced. Imaging findings ranged from normal to contrast-enhancing lesions and cystic encephalomalacia. Received: 1 October 1999/Revised: 25 February 2000/Accepted: 23 May 2000     

Neurologic,MR imaging,and MR spectroscopic findings in eosinophilia myalgia syndrome.

BACKGROUND AND PURPOSEEosinophilia myalgia syndrome (EMS), a multisystemic disease induced by exposure to L-tryptophan, may result in serious CNS abnormalities. The purpose of this study was to determine the pattern of neurologic characteristics, MR imaging abnormalities, and brain neurometabolites in EMS.METHODSSixteen patients with EMS and CNS abnormalities (CNS-EMS) and 12 control subjects underwent evaluation, including medical and neurologic examination, proton MR spectroscopy, and MR imaging.RESULTSNeurologic findings that were increased in CNS-EMS included minor depression (100%), amnesia (88%), and intermittent confusion (38%), although fatigue (31%), motor disorders (31%), recurrent headache (19%), major depression (13%), and dementia (6%) also occurred, but at a lesser significance. Self-reported disability was markedly increased in CNS-EMS. MR imaging findings included subcortical focal lesions, focal lesions in deep white matter, cortical atrophy, ventricular dilatation, and diffuse and periventricular white matter abnormalities. MR spectroscopic findings established two distinct spectral patterns: 1) increased choline-containing compounds, decreased N-acetylaspartate, and increased lipid-macromolecules, consistent with inflammatory cerebrovascular disease; and 2) increased glutamine, decreased myo-inositol, and decreased choline, consistent with acute CNS injury or metabolic encephalopathy.CONCLUSIONNeurologic abnormalities, self-reported disability, brain lesions, and MR spectroscopic abnormalities are common in CNS-EMS. The pattern of cerebral lesions and neurometabolites is consistent with widespread inflammatory cerebrovascular disease. However, a subgroup of patients with CNS-EMS have neurometabolic changes consistent with a metabolic encephalopathy identical or similar to hepatic encephalopathy. The neurologic abnormalities in EMS and related hypereosinophilic syndromes should be interpreted cautiously, with the recognition that both cerebrovascular injury and secondary metabolic encephalopathies may be involved.     

Early characteristics of Sturge-Weber syndrome shown by perfusion MR imaging and proton MR spectroscopic imaging

We report the case of a 9-month-old boy with Sturge-Weber syndrome and new onset of seizure. Perfusion MR imaging showed early changes compatible with impaired venous drainage in the affected hemisphere, whereas proton MR spectroscopic imaging revealed a focal parietal area of elevated choline without significant alteration of N-acetylaspartate levels. The perfusion and subtle metabolic abnormalities are comparable with the extent of the overlying leptomeningeal enhancement, illustrating the early pathophysiological manifestation of this disease.     

Dynamic MR perfusion and proton MR spectroscopic imaging in Sturge-Weber syndrome: correlation with neurological symptoms

PURPOSE: To investigate physiological alterations in Sturge-Weber syndrome (SWS) using MR perfusion imaging (PWI) and proton spectroscopic imaging (MRSI), and their association with neurological status. MATERIALS AND METHODS: Six consecutive patients with a clinically established diagnosis of SWS underwent MRI using a 1.5 Tesla scanner. The protocol consisted of conventional anatomic scans, dynamic PWI, and multislice MRSI. A pediatric neurologist evaluated the neurological scores, and the imaging results were correlated with neurological scores using nonparametric correlation analysis. RESULTS: Two patients had classic neuroimaging findings of unilateral cerebral atrophy with corresponding leptomeningeal enhancement and hypoperfusion (prolonged mean transit time). Two patients had bilateral disease, and two had normal symmetric perfusion. Among clinical measures, the highest correlation was between hemiparesis index and hypoperfused tissue volume (Spearman's correlation coefficient, rho = 0.943, P < 0.05). There was also a trend of correlation, although not statistically significant (P = 0.06), between the hemiparesis score and the NAA/Cr ratio in the mid to posterior centrum semiovale, lateral gray matter (GM), and splenium. CONCLUSION: In SWS, PWI indicates cerebral hypoperfusion predominantly due to impaired venous drainage, with only the most severely affected regions in some patients also showing arterial perfusion deficiency. The extent and severity of the perfusion abnormality and neuronal loss/dysfunction reflect the severity of neurological symptoms and disability, and the highest correlation is found with the degree of hemiparesis. These parameters may be useful as quantitative measures of disease burden; however, further studies in larger number of patients (and with a more homogeneous age range) are required to confirm the preliminary findings reported here.     

Intraventricular meningiomas: MR imaging and MR spectroscopic findings in two cases.

CT, MR imaging, MR spectroscopy, and angiography were performed in two men (ages 21 and 48, respectively) with intraventricular meningioma. In both cases, CT and MR imaging showed large tumors located in the trigone of the right lateral ventricle that enhanced intensely after contrast administration. MR spectroscopy was helpful in supporting a preoperative diagnosis of meningioma in both cases.     

Prostate cancer: evaluation with endorectal MR imaging and three-dimensional proton MR spectroscopic imaging

PURPOSE: To establish the additional value of MR Spectroscopy (3D CSI MRS Three-dimensional Chemical Shift Imaging Magnetic Resonance Spectroscopy) to endorectal MR in the diagnosis and grading of prostate cancer. MATERIALS AND METHODS: MR and 3D CSI MR spectroscopy were performed in 53 patients with suspicion of prostate cancer on the basis of rectal exploration and/or transrectal ultrasound and/or the PSA levels. All the examinations were performed with a 1.5 T imager using an endorectal coil. We acquired axial and coronal T2-weighted FSE sequences, axial T1-weighted SE sequences and PRESS 3D CSI (Point Resolved Spectroscopy 3D Chemical Shift Imaging) sequences localized on the axial T2 images so as to include the prostatic gland while excluding the periprostatic fat. The MR examinations were evaluated by two radiologists unaware of the clinical data, transrectal ultrasound findings, PSA levels and histological findings. The MR and 3D CSI MRS findings were compared with the biopsy findings in 22 cases and with material obtained from laparoscopic prostatectomy in 31 cases. RESULTS: The histological examination revealed adenocarcinoma in 37 cases, prostatitis in 2 cases and no alterations in the remaining 14 cases. The morphologic MR scan showed a sensitivity of 76%, a specificity of 56%, an accuracy of 70%, a PPV of 80% and a NPV of 50%. By combining MR and 3D CSI MRS we obtained a sensitivity of 95%, a specificity of 81%, an accuracy of 91%, a PPV of 92% and a NPV of 87%. Elevated choline concentrations were found both in tumours with a low Gleason score (18 cases) and in those with a high Gleason score (19 cases); instead we found markedly reduced (n=9) or absent (n=4) citrate only in the tumours with a high Gleason score, while we found normal citrate levels in the 18 tumours with a low Gleason score. CONCLUSIONS: The 3D CSI MRS improved the reliability of endorectal MR in the diagnosis and characterisation of prostatic cancer. Moreover, the 3D CSI MRS findings demonstrated a linear correlation with tumour grade.     

van der Knaap syndrome: MR imaging findings including FLAIR, diffusion imaging, and proton MR spectroscopy

A patient is reported with diffuse leukoencephalopathy associated with cystic degeneration of the white matter of the brain (van der Knaap syndrome). The changes were studied by fluid attenuated inversion recovery (FLAIR), and diffusion-weighted MR imaging. The FLAIR sequence revealed suppressed signal of the cysts, and widespread high-signal white matter changes associated with thinned cortices. On diffusion-weighted MR imaging, apparent diffusion coefficient (ADC) values ranged from 3.0 × 10^–3 to 2.7 × 10^–3 mm²/s in the temporal cysts, similar to that of CSF. The ADC values within the parenchyma ranged between 2 × 10^–3 and 2.1 × 10^–3 mm²/s, a value falling between normal parenchyma and cerebrospinal fluid, compared with a control group of three healthy subjects. The changes were also evaluated by proton MR spectroscopy, and were compared with a control group of 12 cases. Magnetic resonance spectroscopy revealed apparently increased NAA/Cr ratios in most parts of the brain. The NAA/Cho ratios were either high or low, and the Cho/Cr ratios were increased or normal in different regions. Received: 27 October 1999; Revised: 9 December 1999; Accepted: 20 December 1999     

Orbital lesions: proton spectroscopic phase-dependent contrast MR imaging

Thirteen orbital lesions in 12 patients were evaluated with both conventional spin-echo magnetic resonance (MR) imaging and phase-dependent proton spectroscopic imaging. This technique, which makes use of small differences in the resonant frequencies of water and fat protons, provides excellent high-resolution images with simultaneous chemical shift information. In this method, there is 180 degrees opposition of phase between fat protons and water protons at the time of the gradient echo, resulting in signal cancellation in voxels containing equal signals from fat and water. In this preliminary series, advantages of spectroscopic images in orbital lesions included better lesion delineation, with superior anatomic definition of orbital apex involvement; more specific characterization of high-intensity hemorrhage with a single pulse sequence; elimination of potential confusion from chemical shift misregistration artifact; further clarification of possible intravascular flow abnormalities; and improved apparent intralesional contrast.     

Sneddon's syndrome: MR imaging findings

Sneddon's syndrome is a systemic disease characterized by generalized livedo racemosa and cerebrovascular disease. We present a case of Sneddon's syndrome which has typical dermatological lesions and occipital infarct demonstrated by both CT and MRI.     

Quantitative proton MR spectroscopic imaging in acute disseminated encephalomyelitis.

Serial MR imaging and quantitative proton MR spectroscopic imaging (MRSI) findings of a 4-year-old boy with acute disseminated encephalomyelitis (ADEM) are reported. Over a 2-month period characterized by an initial illness and two relapses, each with full recovery, MR imaging exhibited the appearance and disappearance of multifocal lesions throughout the CNS that correlated only partly with the neurologic impairment. During one relapse, MRSI revealed low levels of N-acetylaspartate (NAA) within the regions of prolonged T2 signal intensity. All other metabolites were normal. At follow-up, the MR imaging and MRSI abnormalities had fully resolved. MRSI might play an important role in the diagnosis of ADEM, as well as in the elucidation of underlying pathophysiologic processes in this poorly defined disorder of children. This case demonstrates that reduced levels of NAA are not always associated with neuronal loss, irreversible tissue damage, or poor neurologic outcome.     

Prostate cancer: prediction of extracapsular extension with endorectal MR imaging and three-dimensional proton MR spectroscopic imaging.

PURPOSE: To determine if the addition of three-dimensional (3D) proton magnetic resonance (MR) spectroscopic imaging to endorectal MR imaging helps diagnose extracapsular extension (ECE) of prostate cancer. MATERIALS AND METHODS: Endorectal MR imaging and 3D MR spectroscopic imaging were performed in 53 patients with prostate cancer before radical prostatectomy. MR imaging studies were evaluated by two independent readers unaware of histopathologic findings. The presence of ECE was graded on a five-point scale. At 3D MR spectroscopic imaging, cancer was diagnosed if the ratio of choline plus creatine to citrate was 2 or more SDs above normal. The accuracy of MR imaging alone was compared with that of combined MR imaging and 3D MR spectroscopic imaging, with use of the step-section histopathologic results as the standard of reference. RESULTS: For the less experienced reader, the addition of 3D MR spectroscopic imaging to MR imaging significantly improved accuracy (area under the receiver operating characteristic curve [Az] = 0.75 vs Az = 0.62, P < .05). For the more experienced reader, the addition improved accuracy but not significantly (Az = 0.86 vs Az = 0.78). The addition also reduced interobserver variability (Az = 0.86 vs Az = 0.75). CONCLUSION: The addition of 3D MR spectroscopic imaging to MR imaging improves accuracy for less experienced readers and reduces interobserver variability in the diagnosis of ECE of prostate cancer.     

Prostate cancer localization with dynamic contrast-enhanced MR imaging and proton MR spectroscopic imaging

PURPOSE: To prospectively determine the accuracies of T2-weighted magnetic resonance (MR) imaging, dynamic contrast material-enhanced MR imaging, and quantitative three-dimensional (3D) proton MR spectroscopic imaging of the entire prostate for prostate cancer localization, with whole-mount histopathologic section findings as the reference standard. MATERIALS AND METHODS: This study was approved by the institutional review board, and informed consent was obtained from all patients. Thirty-four consecutive men with a mean age of 60 years and a mean prostate-specific antigen level of 8 ng/mL were examined. The median biopsy Gleason score was 6. T2-weighted MR imaging, dynamic contrast-enhanced MR imaging, and 3D MR spectroscopic imaging were performed, and on the basis of the image data, two readers with different levels of experience recorded the location of the suspicious peripheral zone and central gland tumor nodules on each of 14 standardized regions of interest (ROIs) in the prostate. The degree of diagnostic confidence for each ROI was recorded on a five-point scale. Localization accuracy and ROI-based receiver operating characteristic (ROC) curves were calculated. RESULTS: For both readers, areas under the ROC curve for T2-weighted MR, dynamic contrast-enhanced MR, and 3D MR spectroscopic imaging were 0.68, 0.91, and 0.80, respectively. Reader accuracy in tumor localization with dynamic contrast-enhanced imaging was significantly better than that with quantitative spectroscopic imaging (P < .01). Reader accuracy in tumor localization with both dynamic contrast-enhanced imaging and spectroscopic imaging was significantly better than that with T2-weighted imaging (P < .01). CONCLUSION: Compared with use of T2-weighted MR imaging, use of dynamic contrast-enhanced MR imaging and 3D MR spectroscopic imaging facilitated significantly improved accuracy in prostate cancer localization.     

Pantothenate kinase-associated neurodegeneration: MR imaging,proton MR spectroscopy,and diffusion MR imaging findings

We herein report the case of a 15-year-old male patient with pantothenate kinase-associated neurodegeneration. The classic "eye-of-the-tiger" appearance was initially present on the globus pallidi on T2-weighted MR images and had disappeared by the time of the 10-month follow-up examination. Fluid-attenuated inversion recovery images revealed marked hypointensity in the globus pallidi and dentate nuclei and high signal intensity changes in the deep cerebral white matter. Proton MR spectroscopy revealed markedly decreased N-acetylaspartate in the globus pallidi, associated with decreased N-acetylaspartate and increased myoinositol in the deep cerebral white matter. Diffusion MR images (b=1000 s/mm(2)) were negative (normal appearing) for deep cerebral white matter lesions, whereas apparent diffusion coefficient values were slightly increased (1.08-1.12 x 10(-3) mm(2)/s), compared with the apparent diffusion coefficient values from the normal white matter regions. Apparent diffusion coefficient values in the globus pallidi were lower than those in the unaffected thalamus.     

Iliotibial band friction syndrome: MR imaging findings.

Six patients with clinical histories and physical examination results consistent with iliotibial band friction syndrome (ITBFS) were examined with magnetic resonance (MR) imaging. Ill-defined decreased signal intensity on T1-weighted images and increased signal intensity on T2-weighted images was present deep to the iliotibial band, adjacent to the lateral femoral epicondyle. Axial fast imaging with steady-state precession (FISP) gradient-echo sequences were essential in differentiating the ill-defined signal intensity abnormality associated with ITBFS from fluid in the lateral knee joint. None of these patients were found to have lateral meniscal tears, and all responded to conservative measures directed at treating ITBFS. The authors conclude that MR imaging may be useful in confirming or establishing the diagnosis of ITBFS in patients with the appropriate clinical history and distal lateral thigh or lateral knee pain.     

Elbow synovial fold syndrome: MR imaging findings.

OBJECTIVE: We describe the anatomy and MR imaging appearance of elbow plicae. MATERIALS AND METHODS: First, five cadavers were evaluated by sectioning and using MR arthrography for evidence of normal or prominent synovial folds to determine the potential origin of elbow plicae. Next, 164 consecutive MR images were evaluated to determine the frequency of the plicae in a clinical population. Last, we retrospectively studied a selected group of eight patients who underwent preoperative MR imaging and in whom enlarged synovial folds were confirmed at surgery. RESULTS: In the cadavers, the synovial fold appeared to originate from the synovium adjacent to a posterior fat pad. In the clinical population, half the patients showed a synovial fold at the same location; however, most folds were less than or equal to 2 mm in thickness. The eight patients presented clinically with symptoms mimicking an intraarticular body. The synovial fold in symptomatic patients was seen posteriorly just above the olecranon and averaged 3 mm in thickness. CONCLUSION: A synovial fold extending from the posterior fat pad in the elbow is a frequent finding on MR imaging. In a subgroup of patients, plicae, when thickened, may present clinically as a locking elbow. However, overlap exists between the thicknesses of symptomatic and asymptomatic plicae.