Bilateral lesions of the globus pallidus in a young woman.

We report a case of stroke due to cocaine abuse in a 30-year-old woman. The initial examinations pointing to this diagnosis were CT and MRI. Magnetic Resonance Imaging revealed bilateral globus pallidus infarction characterized by restricted Diffusion with low ADC values. There was also a partial hemorrhagic component confirmed on T2* sequence. After gadolinium injection there was a ring enhancement consistent with a blood brain barrier leakage. Similar lesions have been described in post hypoxic-anoxic injuries such as following cardiac arrest, severe blood loss and CO intoxication.

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.

Combined T1-based perfusion MRI and MR angiography in kidney: first experience in normals and pathology.

OBJECTIVES: To investigate the feasibility of implementing quantitative T1-perfusion in the routine MRA-protocol and to obtain a first experience in normals and pathology. MATERIALS AND METHODS: For perfusion imaging, IR-prepared FLASH (one 4 mm slice at mid-renal level, TR 4.4 ms, TE 2.2 ms, TI 180 ms, FA 50 degrees , matrix 128 x 256, bandwidth per pixel 300, 400 dynamics, temporal resolution 0.3 s, total measurement time 2 min) was applied during the injection of 10 ml of standard 0.5 mmol/ml Gadolinium-DTPA solution at 2 ml/s, followed by 3DCE-MRA with bolus tracking (TR 5.4, TE 1.4, FA 40 degrees , matrix 192 x 512, NSA 1, slice thickness 1.5 mm), using a second dose of 0.1 mmol Gadolinium-DTPA per kg body weight with a maximum of 20 ml. The T1-weighted signals (perfusion data) were converted to tissue tracer concentrations and deconvolved with an inflow corrected AIF; blood flow, distribution volume, mean transit time and blood flow heterogeneity were derived. RESULTS: MRA quality was uncompromised by the first bolus administered for perfusion purposes. In the normals, average cortical RBF, RVD and MTT were 1.2 ml/min/ml (S.D. 0.3 ml/min/ml), 0.4 ml/ml (S.D. 0.1 ml/ml) and 21s (S.D. 4s). These RBF values are lower than those found in the literature, probably due to residual AIF inflow effects. The sensitivity of the technique was sufficient to demonstrate altered perfusion in the examples of pathology. CONCLUSION: Combined quantitative T1-perfusion and MRA have a potential for noninvasive renovascular screening and may provide an anatomical and physiological evaluation of renal status.

Quantification of perfusion and permeability in breast tumors with a deconvolution-based analysis of second-bolus T1-DCE data.

PURPOSE: To test the feasibility of using a second-bolus injection, added to a routine breast MRI examination, to measure regional perfusion and permeability in human breast tumors. MATERIALS AND METHODS: In 30 patients with breast tumors, first a routine whole-breast T1-DCE sequence was applied, and the slice where the lesion enhanced maximally was located. At that slice position, T1-weighted MR images were acquired at 0.3-second resolution using a second-bolus dynamic inversion recovery (IR)-prepared turbo field echo (TFE) sequence. A pixel-by-pixel model-independent deconvolution of the relative signal enhancement was performed to estimate the tumor blood flow (TBF), tumor volume of distribution (TVD), mean transit time (MTT), extraction flow product (EF), and extraction fraction (E). In addition to this pilot study, a first appraisal of its sensitivity to tissue type was made on the basis of a small patient cohort. RESULTS: In the malignant tumors, the parametric maps clearly delineated tumors from the breast tissue and enabled visualization of the heterogeneity. The deconvolution analysis provided objective parametric maps of tumor perfusion with a mean TBF (84 +/- 48 mL/100 mL/minute) in malignant tumors in the high range of literature values. CONCLUSION: In terms of these perfusion values, our method appears promising to quantitatively characterize tumor pathophysiology. However, the number of patients was limited, and the separation between malignant and benign groups was not clear-cut. Additional parameters generated through compartment modeling may improve the tumor differentiation.

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.

Inadequacy of the one-dimensional fit-model formula for ultrasound volume assessment of the thyroid gland.

The aim of our study is to assess the best fit-model to assess the thyroid gland formula with a calibrated, automated method namely multi-detector CT to evaluate the most correct fit model in measuring thyroid gland volume.

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.

Prognostic value of perfusion-weighted imaging in brain glioma: a prospective study.

OBJECT: Biopsy targeting based on MR imaging alone may fail to identify malignant areas in brain gliomas. Considering the differences in relative Cerebral Blood Volume (rCBV) ratios reported among tumour grades, we evaluated whether perfusion-weighted MR imaging (PWI) could usefully implement the routine preoperative imaging by detecting those areas bearing a higher yield for malignancy to guide the stereotactic biopsy or the surgical removal. CLINICAL MATERIAL AND METHODS: We studied a series of 55 consecutive patients with newly diagnosed brain glioma using both conventional MR imaging and PWI in the preoperative assessment. The pathological diagnosis was established by stereotactic biopsy in 29 cases and by craniotomy in 24 cases. We evaluated the patient survival to detect undergrading. DISCUSSION: Independent from contrast-enhancement, perfusion-weighted MR imaging improved the target selection in stereotactic biopsy guidance and the removal of malignant areas in tumours amenable to surgery. Particularly sensitive to the perfused part of the tumour as to small regional changes, rCBV maps allowed a better detection of malignant areas. The rCBV ratios correlated significantly to the tumour grade and the final outcome (p < 0.01). CONCLUSIONS: We found PWI valuable in the preoperative assessment of brain gliomas, discriminating high from low-grade gliomas. PWI can easily be performed on widely available MR imaging systems as part of the routine imaging of gliomas.

Bilateral putaminal necrosis due to methanol abuse.

Symmetrical lesions in the basal ganglia are accepted as the characteristic radiological feature of methanol toxicity. A case of chronic deliberate repeated methanol ingestion is presented. The typical MRI findings of basal ganglia lesions on T1 and T2 weighted images, FLAIR, diffusion and T1-weighted post Gadolinium images are presented. To our knowledge, this is the first case in which late diffusion and post contrast MRI images, showing necrotic sequelae due to methanol ingestion, are reported.

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.

Quantification of renal perfusion and function on a voxel-by-voxel basis: a feasibility study.

The feasibility of a voxel-by-voxel deconvolution analysis of T(1)-weighted DCE data in the human kidney and its potential for obtaining quantification of perfusion and filtration was investigated. Measurements were performed on 14 normal humans and 1 transplant at 1.5 T using a Turboflash sequence. Signal time-courses were converted to tracer concentrations and deconvolved with an aorta AIF. Parametric maps of relative renal blood flow (rRBF), relative renal volume of distribution (rRVD), relative mean transit time (rMTT), and whole cortex extraction fraction (E) were obtained from the impulse response functions. For the normals average cortical rRBF, rRVD, rMTT, and E were 1.6 mL/min/mL (SD 0.8), 0.4 mL/mL (SD 0.1), 17s (SD 7), and 22.6% (SD 6.1), respectively. A gradual voxelwise rRBF increase is found from the center of two infarction zones toward the edges. Voxel IRFs showed more detail on the nefron substructure than ROI IRFs. In conclusion, quantitative voxelwise perfusion mapping based on deconvolved T(1)-DCE renal data is feasible, but absolute quantification requires inflow correction. rRBF maps and quantitative values are sufficiently sensitive to detect perfusion abnormality in pathologic areas, but further research is necessary to separate perfusion from extraction and to characterize the different compartments of the nephron on the (sub)voxel level.

Health screening with CT: prospective assessment of radiation dose and associated detriment.

The use of computed tomography (CT) for screening of targeted diseases is gaining much interest in the international medical community. An important aspect in the justification of screening with such a high dose examination is the radiation dose to the patient. The objective of this study was to perform a prospective assessment of the radiation dose and associated risk for deleterious effects from a CT screening programme. The excess lifetime risk of fatal cancer for various screening strategies was quantified by estimating the effective dose and by using age dependent mortality risk factors. The accrued data shows that the excess mortality risk due to screening with CT could be substantial. It ranges from 0.01% up to a few percent, strongly depending on the type and method of screening. Consequently, radiation dose and associate risk should be included as fundamental parameters for outlining and deciding a screening approach with CT. Recent technical developments, such as tube current modulation, are promising tools for dose reduction within the constraint of desired image quality.

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.

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.