Cerebral venous thrombosis: role of CT, MRI and MRA in the emergency setting.

PURPOSE: It is often difficult to diagnose cerebral venous thrombosis (CVT), an uncommon condition that more frequently affects young subjects, is responsible for 1%-2% of strokes in adults and has a subtle clinic onset. The aim of this study was to evaluate the role of computed tomography (CT), magnetic resonance imaging (MRI) and MR venography in the emergency setting and to discuss the risk factors, clinical presentation, outcome and follow-up of this disease. MATERIALS AND METHODS: We retrospectively studied 40 patients with CVT admitted to the emergency department between 1996 and 2006 and examined with unenhanced CT, MRI and MR venography. Fourteen patients also underwent digital subtraction angiography (DSA). RESULTS: Headache was the most common presenting feature (60%). Unenhanced CT showed typical signs (cord or empty delta sign) in 11 cases and nonspecific signs in the other cases. The diagnosis was achieved with MRI and MR venography in 38/40 cases (95%) and with DSA in 2/40 cases. All patients were treated with heparin. Five patients died, and only one of the remaining patients developed serious disability. CONCLUSIONS: Knowledge of the CT, MRI and MR-venography signs of CVT is crucial and enables an early diagnosis and timely treatment with heparin in the majority of cases. DSA should be reserved for doubtful cases only.

Role of diffusion- and perfusion-weighted MR imaging for brain tumour characterisation.

PURPOSE: This study was undertaken to correlate apparent diffusion coefficient (ADC) and relative regional cerebral blood volume (rrCBV) to histological findings in a large series of patients with primary or secondary brain tumours to evaluate diffusion-weighted (DWI) and perfusion-weighted (PWI) imaging in the characterisation of cerebral tumors. MATERIALS AND METHODS: Ninety-eight patients with cerebral tumours, 46 of which were primary (seven grade 0-I, nine low-grade gliomas, two gliomatosis cerebri, nine lymphomas and 19 high-grade gliomas) and 52 secondary, underwent conventional magnetic resonance (MR) imaging completed with DWI and dynamic contrast susceptibility PWI. Both ADC and rrCBV were calculated on a workstation by using Functool 2 software. Student's t test was used to determine any statistically significant differences in the ADC and rrCBV values. RESULTS: Seventeen of 98 tumours were cystic or necrotic (12/17 hypointense and 5/17 hyperintense on DWI); the ADC value of hyperintense cystic areas was 0.97+/-0.23x10(-3) mm2/s. The ADC value of solid tumours varied between 0.64 and 3.5x10(-3) mm2/s. The rrCBV value was 1.4 (sigma 0.66) in low-grade gliomas; 1.22 (sigma 0.25) in lymphomas; 4.5 (sigma 0.85) in grade III gliomas; 3.18 (sigma 1.26) in grade IV gliomas and 2.53 (sigma 1.6) in metastases. CONCLUSIONS: DWI has an important role in the differential diagnosis of cystic cerebral masses but not in tumour characterisation. PWI is helpful in differentiating high-from low-grade gliomas and lymphomas from high-grade gliomas.

Patient dose evaluation by means of DICOM images for a direct radiography system.

PURPOSE: The purpose of this work was to evaluate the statistical distribution of patient dose for different examinations by using the data stored in a DICOM image archive of a direct digital radiography system. MATERIALS AND METHODS: An automatic procedure to extract dose data and exposure parameters from the image archives was implemented. During a 4.5-month period, 8,292 images were collected. Exposure parameters and the air kerma area product (P (KA)) stored in the image DICOM header were examined for each image. The entrance surface air kerma (K (a,e)), a quantity comparable to the current diagnostic reference levels (DRL), was estimated considering the P (KA) and the geometric parameters of each examination. RESULTS: P (KA) and K (a,e ) distributions showed highly variable values. The obtained K (a,e ) values were substantially lower than the DRL. DRL were more than six times the mean value of K (a,e ) distribution for the abdomen anteroposterior (AP) and lumbar spine lateral (LAT) projections, whereas the ratio was equal to 2.7 for posteroanterior (PA) chest examinations. CONCLUSIONS: The method adopted proved to be effective for characterising the dose of each examination by means of the statistical analysis of the dose quantities over extensive samples. The dose values obtained and the comparison with the DRL showed that this radiographic device allows substantial dose savings compared with estimations made for nondigital or for phosphor-based systems.

Diffusion-Weighted Magnetic Resonance Imaging and ADC Maps in the Diagnosis of Intracranial Cystic or Necrotic Lesions. A Retrospective Study on 49 Patients.

This study evaluated the usefulness of diffusion-weighted (DW) magnetic resonance imaging (MRI) and ADC maps in the differential diagnosis of brain abscesses from cystic or necrotic neoplasms. MR images of 49 patients with 54 lesions were examined retrospectively. All patients underwent conventional MRI and DWI, and ADC values were calculated by placing ROIs of 30 mm(2) manually over the cystic part of the lesions. On DWI, all cystic portions of abscesses were hyperintense. Mean ADC values were 0.48×10 mm(2)/s (range 0.41-0.54×10 mm/s) for pyogenic abscesses, 0.73×10 mm(2)/s (range 0.65-0.91×10 mm/s) for mycotic abscesses and 0.6 mm(2)/s for Nocardia abscess. Cystic areas appeared hypointense on DWI in 33/44 tumours (mean value ADC 1.96 mm(2)/s). Eleven tumours (11/44) appeared hyperintense on DWI: eight metastases from lung cancer (mean ADC value 0.86 mm(2)/s, range 0.75-1.2 mm(2)/s), two GBMs (mean 0.7 mm(2)/s, range 0.67-0.76 mm(2)/s) and one anaplastic astrocytoma (ADC value 1.24 mm(2)/s). ADC values may help in differentiating pyogenic abscess from brain tumors or metastatic lesions.

Automated quality control in computed radiography.

PURPOSE: The purpose of this paper is to describe the automation of quality control procedures on photo-stimulable imaging plates by means of an image-processing tool providing automatic reading of the images and automatic calculation of the quality parameters monitored. MATERIALS AND METHODS: Quality-control procedures were performed according to the main available guidelines. The quality assurance programme was applied to several Kodak and Philips devices in four radiological departments. The automatic image-processing tool was developed using public domain software (Java-based ImageJ software) and contains both reading and computation procedures. RESULTS: The quality checks and algorithms described were successfully applied, proving useful for identification of defective plates and for implementation of the quality assurance programme. The use of automation allowed significant savings in the time required for quality checks. CONCLUSIONS: Completely automated image reading allows substantial economic and human resources savings, as it eliminates much of the transfer, reproduction, processing and filing procedures.

Reversible encephalopathy syndrome: report of 12 cases with follow-up.

We report the clinical and neuroradiological features of reversible encephalopathy syndrome and follow-up results in 12 patients. This syndrome seems to be the result of an acute encephalopathy showing with brain edema mainly in the white matter (vasogenic edema). Diffusion-weighted magnetic resonance images are useful to distinguish this entity from acute ischemia. Early recognition and treatment often lead to complete neurological recovery. If unrecognized, the patient's condition can progress to central nervous system failure.

[Check of compliance with quality criteria for diagnostic radiographic images in quality control]. / Verifica del rispetto dei livelli diagnostici di riferimento nella radiodiagnostica nell'ambito dei controlli programmati della qualità.

PURPOSE: To devise and implement a programme of measurements to assess the entrance surface dose for a standard-sized patient and to check the compliance with diagnostic reference levels. MATERIAL AND METHODS: Dose evaluation was performed on 40 radiographic instruments. The exposure parameters were collected for the main radiographic procedures (chest, skull, spine, pelvis, abdomen) each performed with instrument on a standard-sized patient. The output of each X-ray tube at 70, 80, 90, 100, 110 and 120 kV was measured with a solid state detector during quality controls. Beam quality and geometric characteristics of the equipment were also determined. The entrance surface dose for a standard patient was assessed for each procedure carried out with the 40 instruments, thus obtaining a total of 155 radiographic techniques. Finally, the method was validated by comparing the values obtained with the solid state and an ionization chamber for X-ray beam detector. RESULTS: The comparison between the solid state detector and the ionisation chamber demonstrated a good agreement. Results show that reference diagnostic levels are respected in most examinations (147/155) even if exposure values do not always comply with those indicated by European guidelines. The measurement programme seems to be applicable in hospital practice where the large number of radiographics instruments and procedures requires the acquisition and processing of a large number of data. CONCLUSIONS: The evaluation of patient dose during quality control is feasible and allows a first check of compliance with reference levels in order to identify which procedures can be optimised by means of more specific measurements and assessments.

[Magnetic resonance in the study of residual mediastinal masses after therapy of lymphoma]. / La risonanza magnetica nello studio delle masse mediastiniche residue dopo terapia nei linfomi.

Forty-five patients with mediastinal spread of malignant, Hodgkin's and non-Hodgkin's lymphomas were examined with MR Imaging at 0.5 T. Ninety-two examinations were performed at diagnosis and/or during and after treatment to investigate MR capabilities in distinguishing fibrous tissue from active disease in the masses residuing after therapy--which cannot be done by means of CT. MR results indicated T2-weighted sequences to be the most useful. MR results were compared with the data collected from follow-up, clinics, and biology. MR Imaging had high accuracy (92.1%). The number of false negatives was very low, thanks to the low intensity of fibrous tissue, while a relatively high number of false positives was observed, probably due to the difficulties in discriminating inflammatory from neoplastic tissue.

Retraction-convergence nystagmus: clinical and radiological study of 4 cases of vascular origin.

Retraction-convergence nystagmus is a classic finding in extensive and bilateral lesions of the dorsal midbrain, usually neoplastic and, as such, considered to signal a poor prognosis. We report 4 cases of retraction-convergence nystagmus associated with Parinaud syndrome arising from circumscribed lesions of vascular origin--3 hemorrhagic and 1 ischemic--with a completely benign course. The neuroimaging study enabled us to identify involvement of the pretectal areas and posterior commissure as well as of the dorsomedial thalamic nuclei in all cases. It thus seems that one or more of these areas must be involved in the genesis of this nystagmus.

Hematoma of the inferior colliculus: uncommon cause of trochlear nerve deficit and contralateral sensory hemisyndrome.

A 57 year old man consulted us for sudden onset of acuphenes in the right ear, followed by diplopia on forward and downward gaze and paresthesias on the right side of the body. Examination of ocular movements revealed a deficit of the superior oblique muscle of the left eye. CT and MR brainscans imaged a punctate bleed of the left inferior colliculus. The patient was discharged after 16 days still complaining of diplopia on forward and downward gaze. There was no change in neurological status at follow-up. It is rare for an intracerebral hematoma to be located in the midbrain. The case we report is distinguished by the smallness of the lesion and the uncommon neurological deficit it caused.

[Transluminal angioplasty in ambulatory care]. / L'angioplastica transluminale in regime ambulatoriale.

The authors report their experience of 143 transluminal angioplasties performed over a three-year period on outpatients. Retrospective analysis of this case study did not demonstrate any late complications, and the only immediate complication (thrombosis at the arterial puncture) was treated surgically, a few days later, with thromboarterectomy. Of the 121 patients who underwent dilatation, 116 reached their home 6-8 hours after treatment; 4 were hospitalised for the following night, and 1 underwent TEA of the iliac artery. The authors conclude that most transluminal angioplasties can be performed on outpatients.

[Use of nuclear magnetic resonance in cranio-facial pathology. Preliminary study]. / Impiego della risonanza magnetica nucleare nella patologia cranio-facciale. Studio preliminare.

The use of MRT in craniofacial pathology has been evaluated above all as regards the possibility offered by this technique for studying the soft parts with better results than already sophisticated investigations like the CT scan. The technique's limitations are the long duration of the investigation, the impossibility of carrying it out in carriers of pacemakers, the inadequate visualisation of the bone and calcifications, the fairly high cost; the advantages are the fact that ionising radiation is not employed, the ureter sensitivity for the soft parts, the good vessel evaluation and the possibility of obtaining oriented sections in every space plane without moving the patient. The use of MRT is therefore rich in prospects.