MRI in hypertrophic mono- and polyneuropathies.

Different conditions that may lead to enlarged nerves or nerve roots include hereditary motor and sensory neuropathy (HMSN), neurofibromatosis (NF) type 1, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and intraneural perineurioma. Differential diagnosis of hypertrophic mono- and polyradiculopathies remains challenging but is important because of different treatments and prognosis. Magnetic resonance imaging (MRI) can identify the hypertrophic nerve segments and guide a fascicular biopsy. A fascicular biopsy will often be necessary for precise diagnosis.

[Frontal syndrome post cerebral malaria. Case report]. / Un cas de syndrome frontal post-neuropaludisme.

Cerebral malaria is one of the most serious complications of Plasmodium falciparum infection, this protozoa of the Plasmodium family is the only known to induce cerebral malaria. This case is about a frontal lobe syndrome post cerebral malaria in a young man living in an endemic malaria area. This complication is rare and most common during childhood.

Intermittent palpebral oedema following surgery for nasofrontal encephalocele.

PURPOSE: To report a case of intermittent palpebral oedema secondary to a cerebrospinal fluid (CSF) leakage, following encephalocele surgery. CLINICAL CASE: A 9-year-old girl consulted with a history of intermittent swelling of the left upper and lower eyelid. The symptoms started at the age of one. As a relevant fact in her medical history, a neurosurgical repair of a nasofrontal encephalocele at the age of 9 months was withheld. Elaborate imaging studies demonstrated a leakage of cerebrospinal fluid (CSF) into the preseptal periorbital soft tissues, originating from a bony defect in the medial orbital wall. The patient was treated conservatively. CONCLUSION: A CSF leakage in the orbital or periorbital region is a rare finding. In the literature, similar defects have been reported after trauma or associated with neoplasia. To our knowledge, this is the first case of periorbital CSF leakage after encephalocele-surgery reported in the literature.

A case of 'tropical' myelopathy.

We present a case of lower limb sensory disturbances and weakness in a patient originating from Mali. MRI showed a diffuse myelopathy of the cervical and thoracic spinal cord. Serological evaluation of blood and cerebrospinal fluid pointed towards schistosomiasis as the cause. Histological confirmation was made on bladder-biopsy. Treatment with praziquantel and steroids brought marked clinical improvement. This case illustrates the need to keep in mind more exotic causes of myelopathy in those patients coming from endemic regions.

Demonstration of tissue alterations by ultrasonography, magnetic resonance imaging and spectroscopy, and histology in breast cancer patients without lymphedema after axillary node dissection.

Estimates of the incidence of arm swelling after axillary lymph node dissection for breast cancer range from 10 to 37%. Yet the subjective sensation of edema is described in at least 54% of patients. The purpose of this research was to examine the structural changes occurring in the subcutaneous tissue that might explain these subjective complaints using multiple imaging modalities. Two female cadavers with unilateral breast amputation and axillary dissection were studied. The dermal and subcutaneous layers of both arms were visualized with high frequency ultrasonography, and magnetic resonance imaging and spectroscopy (MRS), and tissue biopsies were taken for histological evaluation. On the operated side, ultrasound imaging showed a hyperechogenic subcutis and the fat-to-water relationship in adipose cells was higher as measured by MRS. Dissection of the arms revealed structural adipose tissue changes, which were confirmed by microscopic evaluation.

Prevalence of annular tears and disc herniations on MR images of the cervical spine in symptom free volunteers.

STUDY DESIGN: Prospective MR analysis of the cervical spine of 30 asymptomatic volunteers. OBJECTIVES: To evaluate the prevalence of annular tears, bulging discs, disc herniations and medullary compression on T2-weighted and gadolinium-enhanced T1-weighted magnetic resonance (MR) images of the cervical spine in symptom free volunteers. SUMMARY OF BACKGROUND DATA: Few studies have reported the prevalence of cervical disc herniations in asymptomatic people, none have reported the prevalence of cervical annular tears on MR images of symptom free volunteers. MATERIALS AND METHODS: Thirty symptom-free volunteers (no history or symptoms related to the cervical spine) were examined using sagittal T2-weighted fast spin-echo (SE), sagittal gadolinium-enhanced T1-weighted SE imaging and axial T2(*)-weighted gradient echo (GRE). The prevalence of bulging discs, focal protrusions, extrusions, nonenhancing or enhancing annular tears and medullary compression were assessed. RESULTS: The prevalence of bulging disk and focal disk protrusions was 73% (22 volunteers) and 50% (15 volunteers), respectively. There was one extrusion (3%). Eleven volunteers had annular tears at one or more levels (37%) and 94% of the annular tears enhanced after contrast injection. Asymptomatic medullary compression was found in four patients (13%). CONCLUSION: Annular tears and focal disk protrusions are frequently found on MR imaging of the cervical spine, with or without contrast enhancement, in asymptomatic population. The extruded disk herniation and medullary compression are unusual findings in a symptom-free population.

Treatment of macroprolactinomas with the long-acting and repeatable form of bromocriptine: a report on 29 cases.

Twenty-nine patients with macroprolactinomas were treated by monthly intramuscular injections of the long-acting and repeatable form of bromocriptine (Parlodel-LAR) in doses ranging from 50-150 mg. They were divided into two groups: group I consisted of 22 patients who received Parlodel LAR before transsphenoidal adenomectomy; group II was composed of 7 patients with earlier neurosurgery and of 2 patients from group I not cured by transsphenoidal adenomectomy. Duration of therapy varied from 1-12 months, and a total of 104 injections was given. At nadir day, serum PRL levels were situated between less than 1% and 43% of pretreatment values. At day 28 after the first injection, serum PRL levels varied between less than 1% to 139% of initial values. No difference could be detected between the two groups regarding the percent of PRL inhibition. Long-term treatment with Parlodel-LAR resulted in a sustained inhibition of PRL secretion, except for 1 case. Resumption of menstrual cycles occurred in 4 out of 15 women and correction of hypogonadism in 4 out of 14 men. Amelioration of disturbed visual fields was recorded in 3 out of 8 patients. Diminution of the adenoma volume was radiologically documented in 14 out of 22 cases. Only few and mild side effects were recorded. One patient with partial adrenal deficiency suffered from a syncope, but this was prevented by hydrocortisone supplementation during the subsequent Parlodel-LAR administration. In conclusion, Parlodel-LAR proved effective in the treatment of macroprolactinomas, achieving rapid inhibition of PRL secretion, and in some patients amelioration of hypopituitarism, reduction in tumor size, and improvement in visual fields, and caused no serious side effects. It is a valuable preparation to surgery and can also be used in long-term medical therapy.

Extramedullary plasmacytoma of the cavernous sinus.

We present the case of an 80-year-old male with an history of multiple myeloma (MM) stage I with extramedullary plasmacytoma of the neck, diagnosed 18 months before and in complete remission after radiation therapy and melphalan-prednisone therapy. He was admitted with signs and symptoms characteristic for cavernous sinus syndrome, including diplopia, exophthalmia, ptosis and orbital pain. Magnetic resonance imaging showed a mass lesion in the cavernous sinus, consistent with relapsing extramedullary plasmacytoma. The patient received palliative radiation therapy and high dose dexamethasone, but treatment failed and the patient died. This case represents one of the few reports of extramedullary plasmacytoma of the cavernous sinus. The development of a clinical presentation of cavernous sinus syndrome in a patient with a history of MM or extramedullary plasmacytoma should raise the suspicion of a plasmacytic involvement of the cavernous sinus.

Optimization of sequence parameters in fast MR imaging of the brain with FLASH.

Owing to the intrinsically complex behavior of the signal intensity of fast gradient-refocusing MR sequences, agreement as to the clinically most useful sequence parameters has not yet been reached. This study evaluates the FLASH (fast low-angle shot) sequence for gray-white matter differentiation on normal volunteers at 1.5 T. The FLASH gradient-echo sequence is essentially T1-dependent. For very fast imaging and T1 weighting, the following parameters yield the best results: a flip angle of 30-50 degrees with TR = 20 and TE = 10. To replace T1-weighted SE by the faster FLASH sequence, the best results are achieved by a flip angle of 70-120 degrees with TR = 150-300 and TE = 10 (or shorter, if possible). The most valuable proton-density aspect is achieved by a flip angle of 30 degrees with TR = 300 and TE = 16.

Diffusion-weighted MR imaging of an acute venous stroke: case report.

A patient with a superior sagittal sinus thrombosis had progressively worsening symptoms and signs that resolved after IV heparin therapy. MR imaging revealed abnormalities in diffusion, similar to those seen with acute arterial stroke. Abnormalities shown on a T2-weighted fast spin-echo and fluid-attenuated inversion recovery images resolved completely. The findings in this report contradict those from previous reports that suggest diffusion-weighted imaging with quantitative apparent diffusion coefficients may be used in selecting patients for dural venous sinus thrombolysis.

Use of diffusion-weighted MR imaging in differential diagnosis between intracerebral necrotic tumors and cerebral abscesses.

The differential diagnosis between intracerebral necrotic tumors and cerebral abscesses is frequently impossible with conventional MR imaging. We report two cases of cerebral abscesses that showed high signal on diffusion-weighted echo planar imaging and a strongly reduced apparent diffusion coefficient. This appearance was not present in our cases of necrotic/cystic gliomas (eight cases) and necrotic metastases (two cases). We believe that diffusion-weighted MR imaging may be a diagnostic clue in cases of cerebral "ring-enhancing" masses.

Diffusion-weighted MR imaging of intracerebral masses: comparison with conventional MR imaging and histologic findings.

BACKGROUND AND PURPOSE: The purposes of this study were to find the role of diffusion-weighted MR imaging in characterizing intracerebral masses and to find a correlation, if any, between the different parameters of diffusion-weighted imaging and histologic analysis of tumors. The usefulness of diffusion-weighted imaging and apparent diffusion coefficient (ADC) maps in tumor delineation was evaluated. Contrast with white matter and ADC values for tumor components with available histology were also evaluated. METHODS: Twenty patients with clinical and routine MR imaging/CT evidence of intracerebral neoplasm were examined with routine MR imaging and echo-planar diffusion-weighted imaging. The routine MR imaging included at least the axial T2-weighted fast spin-echo and axial T1-weighted spin-echo sequences before and after contrast enhancement. The diffusion-weighted imaging included an echo-planar spin-echo sequence with three b values (0, 300, and 1200 s/mm(2)), sensitizing gradient in the z direction, and calculated ADC maps. The visual comparison of routine MR images with diffusion-weighted images for tumor delineation was performed as was the statistical analysis of quantitative diffusion-weighted imaging parameters with histologic evaluation. RESULTS: For tumors, the diffusion-weighted images and ADC maps of gliomas were less useful than the T2-weighted spin-echo and contrast-enhanced T1-weighted spin-echo images in definition of tumor boundaries. Additionally, in six cases of gliomas, neither T2-weighted spin-echo nor diffusion-weighted images were able to show a boundary between tumor and edema, which was present on contrast-enhanced T1-weighted and/or perfusion echo-planar images. The ADC values of solid gliomas, metastases, and meningioma were in the same range. In two cases of lymphomas, there was a good contrast with white matter, with strongly reduced ADC values. For infection, the highest contrast on diffusion-weighted images and lowest ADC values were observed in association with inflammatory granuloma and abscess. CONCLUSION: Contrary to the findings of previous studies, we found no clear advantage of diffusion-weighted echo-planar imaging in the evaluation of tumor extension. The contrast between gliomas, metastases, meningioma, and white matter was generally lower on diffusion-weighted images and ADC maps compared with conventional MR imaging. Unlike gliomas, the two cases of lymphomas showed hyperintense signal on diffusion-weighted images whereas the case of cerebral abscess showed the highest contrast on diffusion-weighted images with very low ADC values. Further study is required to find out whether this may be useful in the differentiation of gliomas and metastasis from lymphoma and abscess.

Solitary dorsal intramedullary schwannoma. Case report.

A case of solitary dorsal intramedullary schwannoma diagnosed by magnetic resonance imaging and treated surgically is reported. The authors review the previously published cases. The possible etiology of the tumor as well as some difficulties encountered in the diagnostic procedure and treatment are discussed.

Choice of the regularization parameter for perfusion quantification with MRI.

Truncated singular value decomposition (TSVD) is an effective method for the deconvolution of dynamic contrast enhanced (DCE) MRI. Two robust methods for the selection of the truncation threshold on a pixel-by-pixel basis--generalized cross validation (GCV) and the L-curve criterion (LCC)--were optimized and compared to paradigms in the literature. GCV and LCC were found to perform optimally when applied with a smooth version of TSVD, known as standard form Tikhonov regularization (SFTR). The methods lead to improvements in the estimate of the residue function and of its maximum, and converge properly with SNR. The oscillations typically observed in the solution vanish entirely, and perfusion is more accurately estimated at small mean transit times. This results in improved image contrast and increased sensitivity to perfusion abnormalities, at the cost of 1-2 min in calculation time and hyperintense clusters in the image. Preliminary experience with clinical data suggests that the latter problem can be resolved using spatial continuity and/or hybrid thresholding methods. In the simulations GCV and LCC are equivalent in terms of performance, but GCV thresholding is faster.

A method for myelin fiber orientation mapping using diffusion-weighted MR images.

In the past, the anisotropic diffusion of water molecules in white matter in the brain has been correlated to the basic symmetry of the myelin fibers: water diffuses more readily along the fiber direction than perpendicular to it. As a consequence, diffusion sensitized magnetic resonance imaging can be expected to be useful for studying the fiber orientation. In this work, we present a method for exploiting this type of information to map the fiber orientations in the image plane. It makes use of three diffusion-weighted images with sensitizing gradients along x, y and u, an axis at 45 degrees with respect to x and y. The orientation information contained in these images is summarized in a single image representing the angle between the fiber direction and a fixed axis, making use of a cyclic color scale. The method is evaluated using computer simulations for a variety of diffusion weighting strengths and signal-to-noise ratios, tested on a phantom and illustrated on an in vivo example. An extension to the determination of the fiber orientation in three dimensions is also described.

Actual trends in diagnosis/thrombolytic therapy of acute cerebral stroke.

The recent reports confirm the idea that the selection of cerebral stroke patients for thrombolysis should be performed by MRI. These studies suggested that DWI/PWI/MRA may be able to identify patients who are most likely to benefit from thrombolytics, and that the PWI>DWI pattern in particular is associated with an improved outcome from thrombolytic therapy. However, many questions remain unanswered and a lot of work is necessary before MRI guided thrombolysis in acute cerebral stroke becomes a part of the standard care.

Diagnosis of herniated nucleus pulposus by digital spinal phlebography with false negative CT and/or radiculosaccography.

Saccoradiculography, spinal phlebography or NMR can be performed in cases of discrepancy between CT and clinical symptoms. We believe that the introduction of DSA must generate a renewed interest in spinal phlebography for cases with radicular syndrome and normal CT.

CT-assisted chemonucleolysis.

The safety and success rate of chemonucleolysis are largely dependent on correct needle insertion. The neurological complications of chemonucleolysis are related to inadvertent puncture of the dura, nerve root and/or spinal nerve. To avoid this complication, a puncture angle of 50 degrees to 60 degrees above the sagittal plane is widely recommended (1). Our CT study of the location of the spinal nerve L4-L5 and L5-S1 demonstrates a great variability of this location and also explains some of the possible hazards of 50 degrees to 60 degrees puncture (2). The CT-evaluation of the relationship between the nerve root, spinal nerve and apophyseal joint with respect to the puncture angle is suitable. In our experience, this method is helpful for fast, safe and easy insertion of the needle.

Calcified, cystic brain metastases.

Calcifications are uncommon in metastases. Adenocarcinoma, osteopenic, osteosarcoma, lung and breast carcinoma can be the origin. A rare case of calcified cystic brain metastasis deriving from papillary cystadenocarcinoma is reported.

Pituitary microadenomas: diagnosis with dynamic serial CT, conventional CT and T1-weighted MR imaging before and after injection of gadolinium.

PURPOSE: The few studies comparing CT and MR in the diagnosis of pituitary microadenomas give discordant results. This prospective study compares the value of dynamic serial CT (DSCT), conventional CT (CCT), pre-Gd T1-weighted spin echo (T1SE-Gd) and post-Gd T1-weighted SE (T1SE+Gd) in the detection of pituitary microadenomas. METHODS: The value of CT and MR was assessed in 17 cases, with the surgical confirmation as reference. The CTs and MRs were independently and blindly evaluated by two neuroradiologists. Because the finding at MR and/or CT influenced the selection of patients for surgery, the positive predictive value was calculated. The sensitivity calculation applies only for a specific group of postsurgical patients with positive CT and/or MR (marked with an asterisk for these reasons). RESULTS: In this study, the highest sensitivity* (88% and 82%, respectively, for observers I and II) was achieved by DSCT. The T1SE-Gd and T1SE+Gd (evaluated separately) were slightly inferior (sensitivity* of 76% for observer I). The combination of T1SE-Gd with T1SE+Gd improved the sensitivity* to 94% and 82% respectively, for observers I and II. There was also moderate improvement of sensitivity* by combination of DSCT with conventional CT (94% for observer I). CONCLUSION: These results suggest that rapid injection of a large amount of contrast conjointly with a fast scanning through the pituitary is crucial for the confident detection of microprolactinomas. Taking into account the similar results of the combination DSCT + CT and T1SE-Gd + T1SE+Gd in the detection of microprolactinomas, high field MRI is the first step modality in the evaluation of presumed hypophyseal hyperprolactinemia.