Quantitative Predictive Imaging Biomarkers of Lumbar Intervertebral Disc Degeneration

STUDY DESIGN: Observational comparative study. PURPOSE: To compare fractional anisotropy (FA) maps with T2 values of the nucleus pulposus (NP) and annulus fibrosus (AF) of intervertebral discs in healthy volunteers and patients to develop a predictive disc health scale. OVERVIEW OF LITERATURE: T2-weighted magnetic resonance imaging (MRI) is not sensitive to early morphological changes and provides no quantitative biomarker profile for early degeneration. METHODS: We examined 59 healthy controls and 59 patients with back pain by MRI using T2 relaxometry and diffusion tensor imaging (DTI). Each group was divided into three age subgroups: A (50 years, n=21). We obtained FA values for AF and NP and T2 values for NP for each intervertebral disc. Furthermore, we calculated the FA (AF/NP) ratios. RESULTS: We categorized 590 intervertebral discs from 118 participants, 566 of which were analyzed with T2 relaxometry and DTI. The T2 values were as follows: subgroup A, 55.8±4.4 ms; B, 48.5±6.9 ms; C, 45.8±8.7 ms (p120 ms, 90–100 ms, and 70 ms, respectively (p<0.001). Control subgroup A had higher T2 values and AF/NP ratios than subgroups B and C; the AF values were not significantly different. Control subgroup B had higher T2 values and AF/NP ratios than subgroup C but lower FA (NP). CONCLUSIONS: FA maps of the AF/NP ratio and T2 values of NP are potential microstructure biomarkers of normal and degenerating discs and can help detect early degeneration using a predictive disc health score on a continuous scale.

T2 Relaxometry Using 3.0-Tesla Magnetic Resonance Imaging of the Brain in Early- and Late-Onset Restless Legs Syndrome

BACKGROUND AND PURPOSE: Previous T2 relaxometry studies have provided evidence for regional brain iron deficiency in patients with restless legs syndrome (RLS). Measurement of the iron content in several brain regions, and in particular the substantia nigra (SN), in early- and late-onset RLS patients using T2 relaxometry have yielded inconsistent results. In this study the regional iron content was assessed in patients with early- and late-onset RLS using magnetic resonance imaging (MRI), and compared the results with those in controls. METHODS: Thirty-seven patients with idiopathic RLS (20 with early onset and 17 with late onset) and 40 control subjects were studied using a 3.0-tesla MRI with a gradient-echo sampling of free induction decay and echo pulse sequence. The regions of interest in the brain were measured independently by two trained analysts using software known as medical image processing, analysis, and visualization. The results were compared and a correlation analysis was conducted to investigate which brain areas were related to RLS clinical variables. RESULTS: The iron index in the SN was significantly lower in patients with late-onset RLS than in controls (p=0.034), while in patients with early-onset RLS there was no significant difference. There was no significant correlation between the SN iron index of the late-onset RLS group and clinical variables such as disease severity. CONCLUSIONS: Late-onset RLS is associated with decreased iron content in the SN. This finding supports the hypothesis that regional brain iron deficiency plays a role in the pathophysiology of late-onset RLS.

Fluid-Attenuated Inversion Recovery Hypointensity of the Pulvinar Nucleus of Patients with Alzheimer Disease: Its Possible Association with Iron Accumulation as Evidenced by the T2* Map

OBJECTIVE: We hypothesized that prominent pulvinar hypointensity in brain MRI represents the disease process due to iron accumulation in Alzheimer disease (AD). We aimed to determine whether or not the pulvinar signal intensity (SI) on the fluid-attenuated inversion recovery (FLAIR) sequences at 3.0T MRI differs between AD patients and normal subjects, and also whether the pulvinar SI is correlated with the T2* map, an imaging marker for tissue iron, and a cognitive scale. MATERIALS AND METHODS: Twenty one consecutive patients with AD and 21 age-matched control subjects were prospectively included in this study. The pulvinar SI was assessed on the FLAIR image. We measured the relative SI ratio of the pulvinar to the corpus callosum. The T2* values were calculated from the T2* relaxometry map. The differences between the two groups were analyzed, by using a Student t test. The correlation between the measurements was assessed by the Pearson's correlation test. RESULTS: As compared to the normal white matter, the FLAIR signal intensity of the pulvinar nucleus was significantly more hypointense in the AD patients than in the control subjects (p < 0.01). The pulvinar T2* was shorter in the AD patients than in the control subjects (51.5 +/- 4.95 ms vs. 56.5 +/- 5.49 ms, respectively, p = 0.003). The pulvinar SI ratio was strongly correlated with the pulvinar T2* (r = 0.745, p < 0.001). When controlling for age, only the pulvinar-to-CC SI ratio was positively correlated with that of the Mini-Mental State Examination (MMSE) score (r = 0.303, p < 0.050). Conversely, the pulvinar T2* was not correlated with the MMSE score (r = 0.277, p = 0.080). CONCLUSION: The FLAIR hypointensity of the pulvinar nucleus represents an abnormal iron accumulation in AD and may be used as an adjunctive finding for evaluating AD.

The Relationship between Hippocampal Damage on MRI and Secondarily Generalized Tonic Clonic Seizures in Temporal Lobe Epilepsy : Quantitative and Qualitative MRI Study / 대한간질학회지

PURPOSE: It has been suggested that recurrent seizures may cause the hippocampal formation (HF) damage in temporal lobe epilepsy (TLE). To evaluate whether secondarily generalized tonic clonic seizure (SGTC) is related to the degree of the HF damage on MRI we performed this study. METHODS: We found 42 patients with TLE who had HS on qualitative MRI from epilepsy database. They were divided into unilateral HS (UHS) and bilateral HS (BHS) on qualitative MRI by visual analysis. We performed HF volumetry in 20 and T2 relaxometry in 22 (17 patients were lateralized by quantitative MRI and ictal or interictal EEG). RESULTS: The frequency of status epilepticus and SGTCs in BHS were significantly higher than that in UHS (14% vs 3%, p<0.05 and 60% vs 6%, p<0.05 respectively). Of 17 patients who were lateralized, the frequency of SGTCs was significantly correlated to the ipsilateral (r=0.58, p<0.05) and contralateral (r=0.35, p<0.05) T2 relaxometry as well as inversely to the ipsilateral (r=-0.59, p<0.05) and contralateral (r=-0.52, p<0.05) HF volume. CONCLUSIONS: BHS has the higher frequency of status epilepticus and SGTCs, and the frequency of SGTCs was related to the HF damage.

Clinical Usefulness of T2 Relaxometry in Temporal Lobe Epilepsy

BACKGROUND: Quantitative measurement of hippocampal T2 relaxation time is an objective means of determining the frequency and severity of signal abnormalities. To evaluate the diagnostic properties of T2 relaxometry in temporal lobe epilepsy(TLE), we measured T2 relaxation time of bilateral hippocampi in pathology-proven TLE patients and normal controls. METHODS: We investigated 10 TLE patients who had temporal lobectomy with MR T2 relaxation mapping. All patients underwent in phase I or II studies, and had pathologic diagnosis. Also we measured T2 relaxation time in 10 normal volunteers. RESULTS: The pathologic findings of 10 TLE patients were followings: 8 hippocampal sclerosis (including dual pathology of necrotic granuloma), 1 calcified fibrous nodule, and 1 normal hippocampus. The mean T2 relaxation time of normal controls is 67.5msec, which is lower value than previous reports. All patients with hippocampal sclerosis in pathology showed increased T2 time greater than 2 SD of mean value of normal controls. But, the T2 values are upper normal range in non-hippocampal sclerosis. The lateralizing value of T2 relaxometry is 50% in TLE patients, and 62.5% in pathology-proven hippocampal sclerosis groups. CONCLUSIONS: There is a clear distinction of T2 relaxation time between the patients of hippocampal sclerosis and normal controls or non-hippocampal sclerosis. These findings suggest that the T2 relaxation time is a reliable objective measurement of hippocampal pathology, especially hippocampal sclerosis in TLE.