John M. Gomori

NMR relaxation times of blood: dependence on field strength, oxidation state, and cell integrity.

The variation with field strength or interecho interval of the T1 and T2 relaxation times of oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), and methemoglobin (MHb) in either intact or lysed red blood cells was studied with a variable field (0.19–1.4 T) nuclear magnetic resonance spectroscopy unit. The T2 relaxation time of intracellular HbO2 decreased slightly with increasing field strength and interecho interval. The T2 relaxation times of intracellular Hb and MHb decreased markedly with increasing field strength and interecho interval. This T2 proton relaxation enhancement increased as the square of the applied field strength and was 1.6 times stronger for intracellular MHb than for intracellular Hb. The T2 relaxation enhancement is secondary to the loss of transverse phase coherence of water protons that diffuse across cellular magnetic field gradients. These field gradients occur when an external field is applied to a region with gradients of magnetic susceptibility. The heterogeneity of magnetic susceptibility is caused by the heterogeneous distribution (only intracellular) of the paramagnetic molecules (Hb or MHb). The T2 relaxation times of red cell lysates (homogeneous magnetic susceptibility) were independent of field strength or interecho interval. There was a decrease in the T1 relaxation times when the red cells were lysed. This may be due to an increase in the slow motional components of water molecules, because of the decrease in the average distance between water and hemoglobin molecules in the lysate. The Tl relaxation times of all the MHb samples were shortened because of proton-electron dipolar-dipolar relaxation enhancement. All the Tl relaxation times increased with increasing field strength.

High Field Mr Imaging of Cerebral Venous Thrombosis

High field magnetic resonance (MR) imaging enables us to demonstrate the evolution of cerebral venous thrombosis. Initially, absence of a flow void and collateral venous channels are seen on T1 weighted images (WI). On T2WI thrombus appears hypointense. Hyperintensity is noted in an intermediate stage of thrombosis first on T1WI and later on T2WI. In the late stages recanalization of the vessel occurs with reappearance of the flow void. These findings are specific for venous thrombosis. High field MR may be the imaging modality of choice in the diagnosis of venous thrombosis.

Mutations in the Fatty Acid 2-Hydroxylase Gene Are Associated with Leukodystrophy with Spastic Paraparesis and Dystonia

Myelination is a complex, developmentally regulated process whereby myelin proteins and lipids are coordinately expressed by myelinating glial cells. Homozygosity mapping in nine patients with childhood onset spasticity, dystonia, cognitive dysfunction, and periventricular white matter disease revealed inactivating mutations in the FA2H gene. FA2H encodes the enzyme fatty acid 2-hydroxylase that catalyzes the 2-hydroxylation of myelin galactolipids, galactosylceramide, and its sulfated form, sulfatide. To our knowledge, this is the first identified deficiency of a lipid component of myelin and the clinical phenotype underscores the importance of the 2-hydroxylation of galactolipids for myelin maturation. In patients with autosomal-recessive unclassified leukodystrophy or complex spastic paraparesis, sequence analysis of the FA2H gene is warranted.

MR Imaging of Intracranial Metastatic Melanoma

Ten patients with intracerebral metastases from malignant melanoma were evaluated with magnetic resonance (MR) imaging performed at 1.5 T using spin-echo techniques. On the basis of histopathologic findings in three of 10 cases and CT appearances in all 10 cases, three patterns were identified on analysis of MR signal intensities in both short repetition time/echo time (TR/TE) and long TR/TE spin-echo scans. In comparison to normal cortex, non-hemorrhagic melanotic melanoma appeared markedly hyperintense on short TR/TE images and isointense, mildly hypointense on long TR/TE images. Nonhemorrhagic, amelanotic melanoma appeared isointense or mildly hypointense on short TR/TE and isointense or mildly hyperintense on long TR/TE images. Hemorrhagic melanoma varied in appearance, depending on the stage of hemorrhage. Melanotic, nonhemorrhagic melanoma can be distinguished from early and late subacute hemorrhage by its signal intensity on long TR/TE images. Spin-echo MR appears to be the method of choice for diagnosing melanotic metastases.

Rudimentary horn pregnancy: First-trimester prerupture sonographic diagnosis and confirmation by magnetic resonance imaging

Two cases of rudimentary horn pregnancy diagnosed in the first trimester by sonography and confirmed by magnetic resonance imaging (MRI) are reported. We suggest criteria for early, prerupture sonographic diagnosis of this rare condition.

High-field Mr Imaging of Superficial Siderosis of the Central Nervous System

A case of superficial siderosis of the central nervous system secondary to bleeding from an ependymoma is presented. High-field magnetic resonance imaging showed marginal hypointensity of the cervical cord, medulla oblongata, pons, mesencephalon, anterior cerebellar and basal cerebral surfaces, and cranial nerves (II, V, VIII). These findings were evident in the T2 weighted images.

The prognostic value of the CT scan in conservatively treated patients with intracerebral hematoma.

Prognostic factors for survival and neurological recovery were assessed in 42 patients with non trauma tic intracerebral hematoma (ICH) diagnosed by CT scan. None underwent surgical evacuation of hematoma. CT scans were used to determine location and volume of ICH and presence or absence of intraventricular hemorrhage (IVH). Only 11 patients (26%) died and 17 patients (40.5%) recovered fully. Mortality was associated with: 1) loss of consciousness as a presenting symptom (63.5% mortality rate versus 13% when there was no loss of consciousness at the onset; (p < 0.01). 2) extension of the bleeding into the ventricular system (45% mortality rate versus 9% when hemorrhages were confined to brain parenchy- ma; (p < 0.01). 3) location of hematoma in the posterior fossa (mortality rate of 43% versus 23% for Intrahemispherlc hematomas). Mortality was unaffected by age of patients and size of ICH. Full neurologi- cal and functional recovery occurred mainly when estimated volume of hematomas was less than 15 cc and with lobar hematomas regardless of size. In survivors there is CT evidence of complete resolution of ICH. Our data indicates a favourable outcome in a relatively large percentage of patients with ICH treated conservatively and therefore questions the need for surgical evacuation of hematoma. Stroke Vol 15, No 1, 1984

Joubert Syndrome 2 (JBTS2) in Ashkenazi Jews Is Associated with a TMEM216 Mutation

Patients with Joubert syndrome 2 (JBTS2) suffer from a neurological disease manifested by psychomotor retardation, hypotonia, ataxia, nystagmus, and oculomotor apraxia and variably associated with dysmorphism, as well as retinal and renal involvement. Brain MRI results show cerebellar vermis hypoplasia and additional anomalies of the fourth ventricle, corpus callosum, and occipital cortex. The disease has previously been mapped to the centromeric region of chromosome 11. Using homozygosity mapping in 13 patients from eight Ashkenazi Jewish families, we identified a homozygous mutation, R12L, in the TMEM216 gene, in all affected individuals. Thirty individuals heterozygous for the mutation were detected among 2766 anonymous Ashkenazi Jews, indicating a carrier rate of 1:92. Given the small size of the TMEM216 gene relative to other JBTS genes, its sequence analysis is warranted in all JBTS patients, especially those who suffer from associated anomalies.

Endovascular Stent-Assisted Angioplasty in the Management of Traumatic Internal Carotid Artery Dissections

Background and Purpose— The prognosis of traumatic dissection of the internal carotid artery is worse than for spontaneous dissections. Rapid stenting followed by antiplatelet therapy may prevent complications when anticoagulation therapy is not applicable. Methods— Patients with angiographically proven traumatic carotid artery dissection and hemodynamic significant hemispheric hypoperfusion, or in whom anticoagulant therapy was either contraindicated or failed clinically, were regarded as being at high risk for stroke and were selected for stenting. Results— Ten patients with traumatic dissection underwent stenting. Endovascular treatment reduced mean dissection stenosis from 69% to 8%. During a mean clinical follow-up time of 16 months, none had additional transient ischemic attacks or stroke. Doppler ultrasound studies did not detect any signs of de novo in-stent stenosis. Conclusion— In selected cases of traumatic carotid artery dissections, endovascular stent-assisted angioplasty immediately restored the integrity of the vessel lumen and prevented efficiently the occurrence of new ischemic events, without additional anticoagulation.

Percutaneous vertebroplasty: Technique and results in 192 procedures

Abstract Percutaneous vertebroplasty with acrylic cement (usually polymethylmethacrylate) consists of injecting cement into vertebral bodies weakened by osseous lesions. The objective of this procedure is to obtain an analgesic effect by mechanical stabilization in destructive lesions of the spine. The three major indications are aggressive vertebral hemangiomas, severe or refractory pain related to osteoporotic vertebral fractures, and malignant vertebral tumors. Complications are infrequent, but occur essentially in patients with vertebral malignant tumors. We present our experience with 148 patients that underwent 192 percutaneous PMMA vertebroplasties for the treatment of painful osteoporotic compression fractures (76 patients, 105 vertebral levels), hemangiomas (31 patients, 43 vertebral levels) and neoplasms (31 patients, 43 vertebral levels). In a vast majority of appropriately selected cases and especially in osteoporotic cases, vertebroplasty constitutes a relatively simple procedure with a very high rate of success.