Post-contrast 3D T1-weighted TSE MR sequences (SPACE, CUBE, VISTA/BRAINVIEW, isoFSE, 3D MVOX): Technical aspects and clinical applications.

Post-contrast three-dimensional T1-weighted imaging of the brain is widely used for a broad range of vascular, inflammatory or tumoral diseases. The variable flip angle 3D TSE sequence is now available from several manufacturers (CUBE, General Electric; SPACE, Siemens; VISTA/BRAINVIEW, Philips; isoFSE, Itachi; 3D MVOX, Canon). Compared to gradient-echo (GRE) techniques, 3D TSE offers the advantages of useful image contrasts and reduction of artifacts from static field inhomogeneity. However, the respective role of 3D TSE and GRE MR sequences remains to be elucidated, particularly in the setting of post-contrast imaging. The purpose of this review was (1) to describe the technical aspects of 3D TSE sequences, (2) to illustrate the main clinical applications of the post-contrast 3D T1-w TSE sequence through clinical cases, (3) to discuss the respective role of post-contrast 3D TSE and GRE imaging in the field of neuroimaging.

3D mapping of cerebrospinal fluid local volume changes in patients with hydrocephalus treated by surgery: preliminary study.

OBJECTIVE: To develop automated deformation modelling for the assessment of cerebrospinal fluid (CSF) local volume changes in patients with hydrocephalus treated by surgery. METHODS: Ventricular and subarachnoid CSF volume changes were mapped by calculating the Jacobian determinant of the deformation fields obtained after non-linear registration of pre- and postoperative images. A total of 31 consecutive patients, 15 with communicating hydrocephalus (CH) and 16 with non-communicating hydrocephalus (NCH), were investigated before and after surgery using a 3D SPACE (sampling perfection with application optimised contrast using different flip-angle evolution) sequence. Two readers assessed CSF volume changes using 3D colour-encoded maps. The Evans index and postoperative volume changes of the lateral ventricles and sylvian fissures were quantified and statistically compared. RESULTS: Before surgery, sylvian fissure and brain ventricle volume differed significantly between CH and NCH (P = 0.001 and P = 0.025, respectively). After surgery, 3D colour-encoded maps allowed for the visual recognition of the CSF volume changes in all patients. The amounts of ventricle volume loss of CH and NCH patients were not significantly different (P = 0.30), whereas readjustment of the sylvian fissure volume was conflicting in CH and NCH patients (P < 0.001). The Evans index correlated with ventricle volume in NCH patients. CONCLUSION: 3D mapping of CSF volume changes is feasible providing a quantitative follow-up of patients with hydrocephalus. KEY POINTS: • MRI can provide helpful information about cerebrospinal fluid volumes. • 3D CSF mapping allows quantitative follow-up in communicating and non-communicating hydrocephalus. • Following intervention, fissures and cisterns readjust in both forms of hydrocephalus. • These findings support the hypothesis of suprasylvian block in communicating hydrocephalus. • 3D mapping may improve shunt dysfunction detection and guide valve pressure settings.

Paradoxical embolism following thromboaspiration of an arteriovenous fistula thrombosis: a case report.

INTRODUCTION: Paradoxical embolism is an increasingly reported cause of arterial embolism. Several embolic sources have been described, but thrombosis of an arteriovenous fistula as a paradoxical emboligenic source has not, to the best of our knowledge, been reported. CASE PRESENTATION: A 50-year-old Caucasian woman received a renal graft for primary hyperoxaluria. After transplantation, she was maintained on daily hemodialysis. Thrombosis of her arteriovenous fistula occurred two weeks post-transplantation and was treated by thromboaspiration, which was partially successful. During a hemodialysis session immediately following thromboaspiration, she developed a coma with tetraplegia requiring intensive cardiorespiratory resuscitation. Brain magnetic resonance imaging revealed various hyperdense areas in the vertebrobasilar territory resulting from bilateral occlusion of posterior cerebral arteries. Transesophageal echocardiographic examination showed a patent foramen ovale, while pulse echography of the arteriovenous fistula revealed the persistence of extensive clots that were probably the embolic source. A paradoxical embolus through a patent foramen ovale was suggested because of the proximity of the neurological event to the thrombectomy procedure. CONCLUSIONS: The risk of paradoxical embolism in a hemodialyzed patient with a patent foramen ovale deserves consideration and requires careful evaluation in situations of arteriovenous fistula thrombosis.

Brain ventricular wall movement assessed by a gated cine MR trueFISP sequence in patients treated with endoscopic third ventriculostomy.

The purpose of this study was to investigate the value of brain ventricular wall movement assessment with a gated cine trueFISP MR sequence for the diagnosis of endoscopic third ventriculostomy (ETV) patency. Sixteen healthy volunteers and ten consecutive patients with noncommunicating hydrocephalus were explored with a MR scanner (Siemens, Avanto 1.5 T) before, 1 week and 3 months after ETV. TrueFISP was evaluated qualitatively (ventricular wall movement and CSF flow through ETV) and quantitatively [distance moved (DMLT) during a cardiac cycle by the lamina terminalis]. The third ventricle volume (TVV) was assessed. Statistical analysis was performed using nonparametric tests. There was no motion of the lamina terminalis (LT) detected on preoperative data. A pulsatile motion of the LT was found for patients with a patent ETV and for controls. DMLT and TVV were correlated (r = 0.79, P = 0.006). A transient dysfunction of ETV was successfully diagnosed on the trueFISP sequence with no motion of the LT or CSF flow observed. The trueFISP sequence appears reliable for the diagnosis of ETV patency and provides non-invasive assessment of the movement of the ventricular wall related to CSF pressure changes.

Water diffusion compartmentation at high b values in ischemic human brain.

BACKGROUND AND PURPOSE: We studied the evolution of brain water compartments during the early stage of ischemic stroke. METHODS: Diffusion-weighted imaging was performed at 1.5 T in 10 volunteers and 14 patients with stroke. We used a single-shot echo-planar technique with 11 b values of 0-5000 s/mm(2). Regions of interest were selected in the white matter (WM) and striatum of the volunteers and in the ischemic core of the patients. Measurements were fitted on the basis of a biexponential decay with the b factor as follows: S(b) = S(0)[(f(slow) x exp(-b x ADC(slow)) + (f(fast) x exp(-b x ADC(fast))] where S(b) is the signal intensity in the presence of a diffusion gradient, S(0) is the signal intensity without diffusion sensitization, ADC(slow) and ADC(fast) are the respective apparent diffusion coefficients (ADCs) of slow diffusing compartments (SDCs) and fast diffusing compartments (FDCs), and f(slow) and f(fast) the respective contributions to the signal intensity of SDC and FDC. RESULTS: In healthy subjects, FDC represents 74.3 +/- 3.1% of brain water, with ADC(fast) = (124.6 +/- 12.0) x 10(-5) mm(2)/s and ADC(slow) = (15.5 +/- 3.9) x 10(-5) mm(2)/s. In stroke, decreased FDC (49.1% +/- 10.9%; P = 1.05 x10(-5)) and increased ADC(slow) ([22.4 +/- 8.1] x 10(-5) mm(2)/s; P = 8.07 x 10(-3)) were observed, but ADC(fast) was not significantly changed ([135.6 +/- 25.7] x 10 (-5) mm(2)/s; P =.151). CONCLUSION: The restricted diffusion observed in the early stroke is mainly related to a redistribution of water from the FDC to the SDC.

Longitudinal femoral shaft due to bone insufficiency. A review of three cases.

We report three new cases of longitudinal femoral shaft fracture due to bone insufficiency and review the eight cases reported in the literature. The typical patient is a woman older than 65 years of age who present with mechanical pain in the thigh and/or groin. Palpation of the thigh may reproduce the pain. The diagnosis is often made late because the radiographs are normal initially. However, an early and consistent finding is increased radionuclide uptake along the femoral shaft. The fracture line is readily evidenced by computed tomography but may be difficult to see on magnetic resonance imaging. Use of crutches for 6 weeks to protect the bone from weight bearing ensures healing of the fracture.