Prolonged T2 Relaxation Research Articles

Diet-Induced and Age-Related Changes in the Quadriceps Muscle: MRI and MRS in a Rat Model of Sarcopenia

Background: Knowledge about the molecular pathomechanisms of sarcopenia is still sparse, especially with regard to nutritional risk factors and the subtype of sarcopenic obesity. Objective: The aim of this study was to characterize diet-induced and age-related changes on the quality and quantity of the quadriceps muscle in a rat model of sarcopenia by different magnetic resonance (MR) techniques. Methods: A total of 36 6-month-old male Sprague-Dawley rats were randomly subdivided into 2 groups and received either a high-fat diet (HFD) or a control diet (CD). At the age of 16 months, 15 HFD and 18 CD rats underwent MR at 1.5 T. T1-weighted images as well as T2 relaxation time maps were acquired perpendicular to the long axis of the quadriceps muscles. Maximum cross-sectional area (CSA) of the quadriceps muscle was measured on T1-weighted images, and T2 relaxation times of muscle were assessed in a region without visible intramuscular fat (T2_{lean muscle}) and across the complete CSA (T2_muscle). Furthermore, ¹H-MR spectroscopy was performed to evaluate the relative lipid content of the quadriceps muscles. These measurements were repeated 5 months later in the surviving 8 HFD and 14 CD rats. Results: HFD rats revealed significantly decreased CSA and CSA per body weight (BW) as well as prolonged T2 relaxation times of muscle. A higher weight gain (upper tertile during the first 6 months of diet in CD rats) resulted in a significant change of T2_muscle, but had no relevant impact on CSA. Advancing age up to 21 months led to significantly decreased BW, CSA and CSA/BW, significantly prolonged T2_muscle and T2_{lean muscle} and enlarged lipid content in the quadriceps muscle. Conclusions: In an experimental setting a chronically fat-enriched diet was shown to have a relevant and age-associated influence on both muscle quantity and quality. By translational means the employed MR techniques give rise to the possibility of an early detection and noninvasive quantification of sarcopenia in humans, which is highly relevant for the field of geriatrics.

Quantitative MRI shows cerebral microstructural damage in hemolytic–uremic syndrome patients with severe neurological symptoms but no changes in conventional MRI

Severe neurological symptoms in Shiga toxin-producing Escherichia coli infection associated hemolytic-uremic syndrome (STEC-HUS) are often accompanied by none or only mild alterations of cerebral magnetic resonance imaging (MRI). This study aims to analyze if quantitative MRI is able to reveal cerebral pathological alterations invisible for conventional MRI. In nine patients with STEC-HUS associated severe neurological symptoms but inconspicuous cerebral MRI findings maps of the parameters T2 relaxation time, relative proton density (PD), apparent diffusion coefficient (ADC), and fractional anisotropy (FA) were generated. Quantitative values of these parameters were measured at the basal ganglia, thalamus, and white matter of the frontal and parietal lobe and compared to those of nine age- and sex-matched controls. Significant T2 prolongation (p < 0.01) was found in the basal ganglia of all patients compared to controls. PD and ADC were not significantly altered. A significant reduction of FA in patients was seen at caput nuclei caudati (p < 0.01). Prolonged T2 relaxation time indicates cerebral microstructural damages in these patients despite their inconspicuous MRI findings. T2 relaxometry could be used as a complementary tool for the assessment of metabolic-toxic brain syndromes.

Quantitative MRI Studies of Chronic Brain White Matter Hyperintensities in Migraine Patients

The aim of this study was to examine chronic brain white matter hyperintensities in migraine and to gain data on the characteristics of the lesions. Migraine associates with a higher incidence of magnetic resonance imaging (MRI)-visible white matter signal abnormalities. Several attack-related pathomechanisms have been proposed in the lesion development, including the effect of repeated intracerebral hemodynamic changes. Supratentorial white matter hyperintensities of 17 migraine patients were investigated interictally with quantitative MRI, including quantitative single voxel spectroscopy, diffusion, and perfusion MRI at 3.0-Tesla. The findings were compared with data measured in the contralateral, normal-appearing white matter of migraineurs and in the white matter of 17 healthy subjects. Significantly higher apparent diffusion coefficient values, prolonged T2 relaxation times, and decreased N-acetyl-aspartate and creatine/phosphocreatine concentrations were found in the white matter hyperintensities. The cerebral blood flow and blood volume values were mildly decreased inside the hyperintensities. Differences were not present between the migraine patients' normal-appearing white matter and the white matter of healthy subjects. The MRI measurements denote tissue damage with axonal loss, low glial cell density, and an enlarged extracellular space with an increased extracellular water fraction. These radiological features might be the consequences of microvascular ischemic changes during migraine attacks.

A Quantitative Postmortem MRI Design Sensitive to White Matter Hyperintensity Differences and Their Relationship With Underlying Pathology

White matter hyperintensities (WMHs) associate with both cognitive slowing and motor dysfunction in the neurologically normal elderly. A full understanding of the pathology underlying this clinicoradiologic finding is currently lacking in autopsy-confirmed normal brains. To determine the histopathologic basis of WMH seen on magnetic resonance imaging, we studied the relationship between postmortem fluid-attenuated inversion recovery (FLAIR) intensity and neuropathologic markers of WM lesions (WMLs) that correspond to WMH in cognitively normal aging brains. Samples of periventricular (n = 24), subcortical (n = 26), and normal-appearing WM (NAWM, n = 31) from 4clinically and pathologically confirmed normal cases were examined. The FLAIR intensity, vacuolation, and myelin basic protein immunoreactivity loss were significantly higher in periventricular WML versus subcortical WML; both were higher than in NAWM. The subcortical WML and NAWM had significantly less axonal loss, astrocytic burden, microglial density, and oligodendrocyte loss than those of the periventricular WML. Thus, vacuolation, myelin density, and small vessel density contribute to the rarefaction of WM, whereas axonal density, oligodendrocyte density, astroglial burden, and microglial density did not. These data suggest that the age-related loss of myelin basic protein and the decrease in small vessel density may contribute to vacuolation of WM. Vacuolation enables interstitial fluid to accumulate, which contributes to the prolonged T2 relaxation and elevated FLAIR intensity in the WM.

Cardiac Magnetic Resonance T2 Mapping in the Monitoring and Follow-up of Acute Cardiac Transplant Rejection

Background— Acute rejection is a major factor impacting survival in the first 12 months after cardiac transplantation. Transplant monitoring requires invasive techniques. Cardiac magnetic resonance (CMR), noninvasive testing, has been used in monitoring heart transplants. Prolonged T2 relaxation has been related to transplant edema and possibly rejection. We hypothesize that prolonged T2 reflects transplant rejection and that quantitative T2 mapping will concur with the pathological and clinical findings of acute rejection. Methods and Results— Patients were recruited within the first year after transplantation. Biopsies were graded according to the International Society for Heart Lung Transplant system for cellular rejection with immunohistochemistry for humoral rejection. Rejection was also considered if patients presented with signs and symptoms of hemodynamic compromise without biopsy evidence of rejection who subsequently improved with treatment. Patients underwent a novel single-shot T2-prepared steady-state free precession 4-chamber and 3 short axis sequences and regions of interest were drawn overlying T2 maps by 2 independent blinded reviewers. A total of 74 (68 analyzable) CMRs T2 maps in 53 patients were performed. There were 4 cellular, 2 humoral, and 2 hemodynamic rejection cases. The average T2 relaxation time for grade 0R (n=46) and grade 1R (n=17) was 52.5±2.2 and 53.1±3.3 ms (mean±SD), respectively. The average T2 relaxation for grade 2R (n=3) was 59.6±3.1 ms and 3R (n=1) was 60.3 ms (all P value &lt;0.05 compared with controls). The T2 average in humoral rejection cases (n=2) was 59.2±3.3 ms and the hemodynamic rejection (n=2) was 61.1±1.8 ms ( P &lt;0.05 versus controls). The average T2 relaxation time for all-cause rejection versus no rejection is 60.1±2.1 versus 52.8±2.7 ms ( P &lt;0.05). All rejection cases were rescanned 2.5 months after treatment and demonstrated T2 normalization with average of 51.4±1.6 ms. No difference was found in ventricular function between nonrejection and rejection patients, except in ventricular mass 107.8±10.3 versus 127.5±10.4 g ( P &lt; 0.05). Conclusions— Quantitative T2 mapping offers a novel noninvasive tool for transplant monitoring, and these initial findings suggest potential use in characterizing rejections. Given the limited numbers, a larger multi-institution study may help elucidate the benefits of T2 mapping as an adjunctive tool in routine monitoring of cardiac transplants.

Descending corticospinal tract Wallerian degeneration after stroke: an old sign, a new prognostic marker?

right hemiplegia reached its plateau at month-3 (FIM motor score: 42/91). At that time, MRI revealed the signs of descending corticospinal tract Wallerian degeneration (DCST-WD) (Fig. 2). The MRI feature of DCST-WD is prolonged T2 relaxation times with or without shrinkage of ipsilateral cerebral peduncle and pons [1]. This feature is more evident 3–6 months after stroke but can appear as early as 5 weeks and could persist for more than 10 months [1]. Recent studies suggest that early or serial DCST-WD signs on MRI or diffusion weighted or diffusion tensor imaging might be new biological markers of motor prognosis after stroke [2].

Cardiac magnetic resonance T2 mapping for monitoring acute cardiac transplant rejection

Cardiac transplantation is the treatment for some patients with end-stage heart failure. After transplantation asymptomatic acute allograft rejection is a major factor impacting survival in the first 12 months. Current transplant monitoring requires frequent right heart catheterizations, endomyocardial biopsies (EMB), and echocardiography. CMR imaging, comparatively less invasive, has been studied previously in the transplanted heart and prolonged T2 relaxation has shown correlation to transplant edema and rejection [1]. We hypothesize that prolonged T2 relaxation in transplant edema reflects rejection, and that quantitative T2 mapping will correlate with pathological and clinical findings.

Severe thyroid-associated orbitopathy in Hashimoto's thyroiditis. Report of 2 cases

Thyroid-associated orbitopathy (TAO) is characterized by immune-mediated inflammation of the extraocular muscles surrounding orbital connective tissue and adipose tissue. Severe orbitopathy related to autoimmune thyroid disease often occurs in patients with Grave's disease, but it is rare in patients with Hashimoto's thyroiditis. The pathogenesis of TAO is unclear. Several studies have noted a strong correlation between the levels of antibodies to thyrotropin receptor antibody (TRAb) and TAO in Graves' disease. Mild upper eyelid retraction has been reported to be common in Hashimoto's thyroiditis patients, however severe orbitopathy is rare. We report two cases of severe TAO in patients with Hashimoto's thyroiditis who required systemic glucocorticoid therapy and orbital irradiation to treat the TAO. The activity of the TAO was high in both patients, because their clinical activity scores (CAS) for the orbitopathy were high, and magnetic resonance imaging (MRI) showed enlargement of the extraocular muscles and an increase in T2 signal intensity and prolonged T2 relaxation time which indicate an active stage of inflammation. We tested the presence of TRAb by three different assays and were negative in both patients. Since the eye muscle damage cannot be due to TSH receptor antibodies, other pathogenetic mechanisms may be responsible for the orbitopathy in patients with Hashimoto's thyroiditis.

MRI of the eye muscles in a case of ophthalmoplegia caused by common carotid artery occlusion suggests ischemic myopathy

Ocular muscle palsies following carotid artery disease is thought to be caused by ischemia of the cranial oculomotor nerves but it may also be due to ischemia of the extraocular muscles (EOM). We studied a patient with common carotid artery occlusion syndrome (CCAOS) to elucidate the two competing hypotheses. MRI and sonography of the orbita showed oedematous swelling of all left EOM. MRI short-tau inversion recovery (STIR) sequences showed hyperintensities and a prolonged T2-relaxation time in EOM indicating muscle oedema. It decreased within two weeks as ophthalmoplegia improved. For several reasons ischemic EOM myopathy rather than ischemic neuropathy seems to be the morphological correlate of ophthalmoplegia after ipsilateral CCAOS in this patient.

T2 relaxation time abnormalities in bipolar disorder and schizophrenia

There are substantial abnormalities in the number, density, and size of cortical neurons and glial cells in bipolar disorder and schizophrenia. Because molecule-microenvironment interactions modulate metabolite signals characteristics, these cellular abnormalities may impact transverse (T2) relaxation times. We measured T2 relaxation times for three intracellular metabolites (N-acetylaspartate+N-acetylaspartylglutamate, creatine+phosphocreatine, and choline-containing compounds) in the anterior cingulate cortex and parieto-occipital cortex from 20 healthy subjects, 15 patients with bipolar disorder, and 15 patients with schizophrenia at 4 T. Spectra used in T2 quantification were collected from 8-cc voxels with varying echo times (30 to 500 ms, in 10-ms steps). Both bipolar disorder and schizophrenia groups had numerically shorter T2 relaxation times than the healthy subjects group in both regions; these differences reached statistical significance for creatine+phosphocreatine and choline-containing compounds in bipolar disorder and for choline-containing compounds in schizophrenia. Metabolite T2 relaxation time shortening is consistent with reduced cell volumes and altered macromolecule structures, and with prolonged water T2 relaxation times reported in bipolar disorder and schizophrenia. These findings suggest that metabolite concentrations reported in magnetic resonance spectroscopy studies of psychiatric conditions may be confounded by T2 relaxation and highlight the importance of measuring and correcting for this variable.

Usefulness of muscle denervation as an MRI sign of peripheral nerve pathology

Peripheral nerve disorders may be classified into compressive or entrapment neuropathies and non-compressive neuropathies. Muscle denervation recognized on MRI may be a useful sign in the diagnosis of peripheral nerve disorders. Acute or subacute denervation results in prolonged T2 relaxation time, producing increased signal in skeletal muscle on short tau inversion-recovery and fat-suppressed T2-weighted images. Chronic denervation produces fatty atrophy of skeletal muscles, resulting in increased muscle signal on T1-weighted images. This review will outline and illustrate the various ways that muscle denervation as seen on MRI may assist in the diagnosis and localization of peripheral nerve disorders.

Magnetic Resonance Imaging Findings of Angiosarcoma of the Scalp

The purpose of this study was to investigate the magnetic resonance (MR) imaging findings of angiosarcoma of the scalp retrospectively. Eight patients with angiosarcoma of the scalp were included in this study. All patients were examined with 1.5-T MR imaging units and commercially available head coils. In all 8 patients, MR images revealed thickened scalp or tumors with prolonged T1 and T2 relaxation times. They were well enhanced. T2-weighted MR imaging with fat saturation and contrast-enhanced T1-weighted MR imaging with fat saturation clearly showed tumors invading the subcutaneous fat tissue and muscles. In 4 patients, the tumors were larger on MR images than on inspection. Magnetic resonance imaging was useful in determining the extent of angiosarcoma of the scalp because it visualized the tumor invasion into surrounding structures that could not be seen on physical inspection.

Unilateral striatal damage following status epilepticus of ipsilateral frontal lobe origin

A 35-year-old man with an old contusional haematoma in the right frontal lobe developed status epilepticus (SE) of right frontal origin. On magnetic resonance (MR) images 10 days after SE, the right striatum showed signal enhancement with Gd-DTPA administration. Subsequent MR imaging 1 month later indicated prolonged T1 and T2 relaxation times in the right striatum. Prolonged seizure activity in the frontal lobe may have induced excitatory neurotoxicity in the ipsilateral striatum, with occurrence of delayed neuronal damage as a result.

Prolonged Febrile Convulsions Produce More Severe Mesial Temporal Sclerosis.

Quantitative Magnetic Resonance Characterization of Mesial Temporal Sclerosis in Childhood Scott RC, Gadian DG, Cross JH, Wood SJ, Neville BG, Connelly A Neurology 2001;56:1659–1665 Objective To investigate whether quantitative magnetic resonance (MR) techniques can be used to distinguish between mesial temporal sclerosis in patients with a history of prolonged febrile convulsion and in patients without such a history. Methods Quantitative hippocampal T2 relaxometry, hippocampal volumetry, and single-voxel 1H-magnetic resonance spectroscopy (MRS) data were acquired from 16 children who subsequently underwent temporal lobe resections for intractable temporal lobe epilepsy and histologically were shown to have sclerosis of the horn of Ammon. Eight children had a history of prolonged febrile convulsion in early childhood, and eight children had other or no associations. Results Patients with a history of prolonged febrile convulsion had smaller hippocampi (p = 0.02) and prolonged T2 relaxation time (p = 0.03) ipsilateral to the seizure focus when compared with patients without such a history. There was also more side-to-side asymmetry of T2 relaxation time (p = 0.004) and hippocampal volume (p = 0.02) in the patients with a history of prolonged febrile convulsion than in those with other or no associations. No differences between the groups were identified by using 1H-MRS Conclusions These data support the view that there are at least two types of mesial temporal sclerosis. There may be several pathogenetic pathways from initial insult to later mesial temporal sclerosis, and these pathways are, at least in part, dependent on the initial insult.

Prolonged Febrile Convulsions Produce More Severe Mesial Temporal Sclerosis

Quantitative Magnetic Resonance Characterization of Mesial Temporal Sclerosis in ChildhoodScott RC, Gadian DG, Cross JH, Wood SJ, Neville BG, Connelly ANeurology 2001;56:1659–1665ObjectiveTo investigate whether quantitative magnetic resonance (MR) techniques can be used to distinguish between mesial temporal sclerosis in patients with a history of prolonged febrile convulsion and in patients without such a history.MethodsQuantitative hippocampal T2 relaxometry, hippocampal volumetry, and single-voxel 1H-magnetic resonance spectroscopy (MRS) data were acquired from 16 children who subsequently underwent temporal lobe resections for intractable temporal lobe epilepsy and histologically were shown to have sclerosis of the horn of Ammon. Eight children had a history of prolonged febrile convulsion in early childhood, and eight children had other or no associations.ResultsPatients with a history of prolonged febrile convulsion had smaller hippocampi (p = 0.02) and prolonged T2 relaxation time (p = 0.03) ipsila...

Quantitative magnetic resonance characterization of mesial temporal sclerosis in childhood.

To investigate whether quantitative MR techniques can be used to distinguish between mesial temporal sclerosis in patients with a history of prolonged febrile convulsion and in patients without such a history. Quantitative hippocampal T2 relaxometry, hippocampal volumetry, and single voxel (1)H-MRS data were acquired from 16 children who subsequently underwent temporal lobe resections for intractable temporal lobe epilepsy and histologically were shown to have sclerosis of the horn of Ammon. Eight children had a history of prolonged febrile convulsion in early childhood and eight children had other or no associations. Patients with a history of prolonged febrile convulsion had smaller hippocampi (p = 0.02) and prolonged T2 relaxation time (p = 0.03) ipsilateral to the seizure focus when compared with patients without such a history. There was also more side-to-side asymmetry of T2 relaxation time (p = 0.004) and hippocampal volume (p = 0.02) in the patients with a history of prolonged febrile convulsion than in those with other or no associations. No differences between the groups were identified using (1)H-MRS. These data support the view that there are at least two types of mesial temporal sclerosis. There may be several pathogenetic pathways from initial insult to later mesial temporal sclerosis, and these pathways are, at least in part, dependent on the initial insult.

Central pontine myelinolysis

Central pontine myelinolysis (CPM), a neurologic disorder caused most frequently by rapid correction of hyponatremia, is characterized by demyelination that affects the central portion of the base of the pons. There are no inflammatory changes, and blood vessels are normal. Clinical features usually reflect damage to the descending motor tracts and include spastic tetraparesis, pseudobulbar paralysis, and the locked-in syndrome. Magnetic resonance imaging of the brain, the imaging procedure of choice, shows an area of prolonged T1 and T2 relaxation in the central pons, which may have a characteristic shape. Recovery varies, ranging from no improvement to substantial improvement. To avoid CPM, correction of serum sodium in patients with hyponatremia should not exceed 12 mEq/24 h. We describe a case of CPM in a hyponatremic patient who presented with a cerebellar syndrome with no pyramidal tract involvement and in whom the rate of correction of serum sodium was within the recommended limits.

A pilot study using magnetic resonance imaging to determine the pattern of muscle group recruitment by rowers with different levels of experience.

To determine whether it was possible using magnetic resonance imaging (MRI) to define the pattern of muscle recruitment in a specific sport (rowing) and to see whether there were differences in this pattern between athletes of different experience. It has been shown that during vigorous exercise the water content of muscle increases transiently. This can be observed using MRI, where the prolonged T2 relaxation time of muscle can be demonstrated. In this study we have exploited the increase in signal seen in exercised muscle on short TI inversion recovery (STIR) sequences, to show how rowers of different experience use different muscle groups. We have shown that trained athletes recruit selected muscle groups to carry out a given task, which they carry out more efficiently than untrained or less experienced athletes. We have provided the basis of potential research to refine training methods, in order to develop specific muscle groups in athletes, in the hope of achieving a higher level of performance at an earlier stage in their training. We have also defined a technique that may be of clinical value in cases of muscle dysfunction.

Characterization of tissue damage in multiple sclerosis by nuclear magnetic resonance.

Nuclear magnetic resonance (NMR) imaging is an established diagnostic medium to diagnose multiple sclerosis (MS). In clinically stable MS patients, NMR detects silent disease activity, which is the reason why it is being used to monitor treatment trials, in which it serves as a secondary outcome parameter. The absence of a clear correlation with clinical disability, the so-called 'clinico-radiological' paradox, and the poor predictive value of NMR prohibit the use of NMR as a primary outcome parameter in clinical trials. This is--among others--a result of the limited histopathological specificity of conventional, or 'T2-weighted' imaging, the most commonly used NMR technique. In this paper we review additional NMR techniques with higher tissue specificity, most of which show marked heterogeneity within NMR-visible lesions, reflecting histopathological heterogeneity. Gadolinium enhancement identifies the early inflammatory phase of lesion development, with active phagocytosis by macrophages. Persistently hypointense lesions on T1-weighted images ('black holes') relate to axonal loss and matrix destruction, and show a better correlation with clinical disability. Marked prolongation of T1 relaxation time correlates with enlargement of the extracellular space, which occurs as a result of axonal loss or oedema. Axonal viability can also be measured using the concentration of N-acetyl aspartate (NAA) using NMR spectroscopy; this technique is also capable of showing lactate and mobile lipids in lesions with active macrophages. The multi-exponential behaviour of T2 relaxation time in brain white matter provides a tool to monitor the myelin water component in MS lesions (short T2 component) as well as the expansion of the extracellular space (long T2 component). Chemical exchange with macromolecules (e.g. myelin) can be measured using magnetization transfer imaging, and correlates with demyelination, axonal loss and matrix destruction. Increased water diffusion has been found in MS lesions (relating to oedema and an expanded extracellular space) and a loss of anisotropy may indicate a loss of fibre orientation (compatible with demyelination). Apart from the histopathological heterogeneity within focal MS lesions, the normal-appearing white matter shows definite abnormalities with all quantifiable NMR techniques. A decrease in the concentration of NAA, decreased magnetization transfer values and prolonged T1 relaxation time values are probably all related to microscopic abnormalities, including axonal damage. This 'invisible' lesion load may constitute a significant proportion of the total lesion load but is not visible on conventional NMR. Similarly, mechanisms for clinical recovery exist, which are not distinguished using MR imaging. Therefore, it is highly unlikely that the clinico-radiological paradox will ever be solved completely. However, NMR provides an opportunity to sequentially measure tissue changes in vivo. Using MR parameters with (presumed) histopathological specificity, the development of (irreversible) tissue damage can be monitored, which perhaps allows the identification of factors that determine lesional outcome in MS. Since the absence of severe tissue destruction is prognostically favourable, NMR monitoring of the extent to which such changes can be prevented by treatment will ultimately benefit the selection of future treatment strategies.

Contribution of T2Relaxation Time Mapping in the Evaluation of Cryptogenic Temporal Lobe Epilepsy

In this study we compared the results of visual analysis of MR imaging with T2relaxation time mapping of the mesial structures in a group of 97 patients with cryptogenic temporal lobe epilepsy. All patients underwent a clinical neurological examination, neuropsychological investigation, prolonged video-EEG monitoring, SPECT imaging, MR imaging, and T2relaxation time mapping. T2relaxation times were estimated with a Carr–Purcell–Meiboom–Gill pulse sequence with 48 echoes (15 to 720 ms). The mean T2relaxation time value was 118.5 ± 2 ms in the hippocampi and 120.3 ± 1.9 ms in the amygdala of 21 healthy subjects used as controls. T2relaxation mapping revealed mesial temporal sclerosis in 91.8% of the patients (often involving both the hippocampus and the amygdala) and evidenced bilateral involvement in 44.6% of the patients against 72.2 and 6.2%, respectively, for MR imaging. The ipsilateral and contralateral hippocampal T2relaxation time values did significantly correlate with seizure frequency and the contralateral hippocampal T2relaxation time value with the duration of epilepsy. In conclusion, this quantitative method is highly sensitive for the detection of mesial temporal sclerosis and permits a better evaluation of the apparently normal contralateral mesial structures.