Associations among q-space MRI, diffusion-weighted MRI and histopathological parameters in meningiomas.

OBJECTIVES: The purposes of this MR-based study were to calculate q-space imaging (QSI)-derived mean displacement (MDP) in meningiomas, to evaluate the correlation of MDP values with apparent diffusion coefficient (ADC) and to investigate the relationships among these diffusion parameters, tumour cell count (TCC) and MIB-1 labelling index (LI). METHODS: MRI, including QSI and conventional diffusion-weighted imaging (DWI), was performed in 44 meningioma patients (52 lesions). ADC and MDP maps were acquired from post-processing of the data. Quantitative analyses of these maps were performed by applying regions of interest. Pearson correlation coefficients were calculated for ADC and MDP in all lesions and for ADC and TCC, MDP and TCC, ADC and MIB-1 LI, and MDP and MIB-1 LI in 17 patients who underwent subsequent surgery. RESULTS: ADC and MDP values were found to have a strong correlation: r = 0.78 (P = <0.0001). Both ADC and MDP values had a significant negative association with TCC: r = -0.53 (p = 0.02) and -0.48 (P = 0.04), respectively. MIB-1 LI was not, however, found to have a significant association with these diffusion parameters. CONCLUSION: In meningiomas, both ADC and MDP may be representative of cell density. KEY POINTS: • Diffusion-weighted MRI offers possibilities to assess the aggressiveness of meningiomas. • The q-space imaging-derived mean displacement correlates strongly with apparent diffusion coefficients. • Both diffusion parameters showed a strong negative association with tumour cell counts. • Derived mean displacement may help assess the aggressiveness of meningiomas preoperatively.

Age-related white matter changes in high b-value q-space diffusion-weighted imaging.

INTRODUCTION: To assess and compare age-related diffusion changes in the white matter in different cerebral lobes, as quantified by diffusion-weighted imaging (DWI) and high b-value q-space imaging (QSI). METHODS: Seventy-three cases without neurological symptoms or imaging abnormalities were grouped by age as young (<30 years, n = 20), middle-aged (30-49 years, n = 19), old (50-69 years, n = 18), and very old (> 70 years, n = 16) and imaged by a 1.5-T MR scanner for DWI and QSI. Apparent diffusion coefficient (ADC) and mean displacement (MDP) values were calculated in the white matter of frontal, parietal, and temporal lobes and compared using Dunnett's test, with the young group as a control. RESULTS: MDP values in frontal and parietal lobes were significantly higher in old and very old age groups than in the young, while those in the temporal lobes were significantly higher only in the very old group. ADC values were significantly higher in all three lobes in the very old group. CONCLUSION: QSI is more sensitive than DWI to age-related myelin loss in white matter.

Diffusion-weighted imaging in optic neuritis.

PURPOSE: To evaluate imaging characteristics of optic nerves by using magnetic resonance imaging, especially diffusion-weighted imaging (DWI) with apparent diffusion coefficient measurements in acute and chronic phases of optic neuritis (ON). MATERIALS AND METHODS: A retrospective study was conducted by using records of 14 patients with clinically suspected acute ON (15 nerves), 5 chronic ON (7 nerves), and 11 normal volunteers with no eye symptoms were used as controls. Magnetic resonance imaging was performed by a 1.5T scanner. Affected nerves were evaluated for sizes, signal characteristics on DWI and T2-weighted imaging (T2WI), contrast enhancement, and apparent diffusion coefficient values. Visually assessed characteristics were compared between the acute and chronic, whereas apparent diffusion coefficient values were assessed among acute ON, chronic ON, and the control groups by using the Fisher exact test and Mann-Whitney U test. RESULTS: There were significant differences in the diameter of the optic nerves, hyperintensity on DWI, and enhancement characteristics on post-enhanced images in acute and chronic phases of ON (P = .0001, P < .0001, and P = .0022, respectively), apparent diffusion coefficient values of the optic nerves in acute ON, chronic ON, and control groups also differed significantly from each other. CONCLUSION: In conclusion, DWI can add valuable information in assessment of damage to nerve and neuronal barriers and thus in predicting recovery in cases of ON.

Effect of Temporal Sampling Rate on Estimates of the Perfusion Parameters for Patients with Moyamoya Disease Assessed with Simultaneous Multislice Dynamic Susceptibility Contrast-enhanced MR Imaging.

PURPOSE: The effect of temporal sampling rate (TSR) on perfusion parameters has not been fully investigated in Moyamoya disease (MMD); therefore, this study evaluated the influence of different TSRs on perfusion parameters quantitatively and qualitatively by applying simultaneous multi-slice (SMS) dynamic susceptibility contrast-enhanced MR imaging (DSC-MRI). METHODS: DSC-MRI datasets were acquired from 28 patients with MMD with a TSR of 0.5 s. Cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP), and time to maximum tissue residue function (Tmax) were calculated for eight TSRs ranging from 0.5 to 4.0 s in 0.5-s increments that were subsampled from a TSR of 0.5 s datasets. Perfusion measurements and volume for chronic ischemic (Tmax ≥ 2 s) and non-ischemic (Tmax < 2 s) areas for each TSR were compared to measurements with a TSR of 0.5 s, as was visual perfusion map analysis. RESULTS: CBF, CBV, and Tmax values tended to be underestimated, whereas MTT and TTP values were less influenced, with a longer TSR. Although Tmax values were overestimated in the TSR of 1.0 s in non-ischemic areas, differences in perfusion measurements between the TSRs of 0.5 and 1.0 s were generally minimal. The volumes of the chronic ischemic areas with a TSR ≥ 3.0 s were significantly underestimated. In CBF and CBV maps, no significant deterioration was noted in image quality up to 3.0 and 2.5 s, respectively. The image quality of MTT, TTP, and Tmax maps for the TSR of 1.0 s was similar to that for the TSR of 0.5 s but was significantly deteriorated for the TSRs of ≥ 1.5 s. CONCLUSION: In the assessment of MMD by SMS DSC-MRI, application of TSRs of ≥ 1.5 s may lead to deterioration of the perfusion measurements; however, that was less influenced in TSRs of ≤ 1.0 s.

Mean displacement map of spine and spinal cord disorders using high b-value q-space imaging-feasibility study.

BACKGROUND: Q-space analysis is a new metric that uses multiple, high b-value, diffusion-weighted magnetic resonance (MR) data. This technique shows promising results as a tool to provide information complementary to that of other imaging techniques used on biological tissue in vivo. PURPOSE: To investigate the use of a mean displacement (MDP) map of high b-value, q-space imaging (QSI) to characterize spinal and spinal cord lesions in vivo. MATERIAL AND METHODS: Eight patients with spine or spinal cord disorders (two neurinomas, one myeloma, three cases of syringohydromyelia, and two cases of cervical spondylosis) were included. The MR imaging protocol consisted of conventional MR sequences, conventional diffusion-weighted imaging (DWI; b = 1000), and high b-value QSI with a maximum q value of 836.9 cm(-1). Apparent diffusion coefficient (ADC) maps of conventional DWI and MDP maps of QSI data were obtained and region-of-interest analyses for the lesions were performed. RESULTS: MDP values of normal spinal cord, cerebrospinal fluid (CSF), and tumor parenchyma were 6.57 ± 0.52, 17.6 ± 2.75, and 8.49 ± 2.09, respectively (µm, mean ± standard deviation). In general, MDP maps were not well correlated with the corresponding ADC maps at the pathologic lesions. Spondylotic lesions tended to have higher MDP values than normal spinal cord, whereas syringohydromyelia produced MDP values slightly lower than those of CSF. CONCLUSION: The heterogeneous MDP values were probably due to differences in tissues and pathologic structures. This technique has potential to provide additional clinical information to that obtained with conventional MR imaging.

Can balloon-occluded retrograde transvenous obliteration be performed for gastric varices without gastrorenal shunts?

PURPOSE: To evaluate the feasibility for balloon-occluded retrograde transvenous obliteration (BRTO) for gastric varices without gastrorenal shunts. MATERIALS AND METHODS: Of 76 patients with gastric varices who were referred for treatment by BRTO, 11 did not have gastrorenal shunts. Contrast medium-enhanced computed tomography (CT) was performed in all patients; seven patients also underwent CT during splenic arteriography. BRTO was performed to insert a balloon catheter into the main draining vein and inject 5% ethanolamine oleate into gastric varices under the temporary balloon occlusion. RESULTS: The main draining veins were the subphrenic transverse part of the inferior phrenic vein to the inferior vena cava in five patients, the pericardial vein to the left brachiocephalic vein in two, and the paraesophageal vein to the azygos vein in two. In two patients, the main draining vein was unknown. The overall success rate of BRTO in the nine cases with main draining veins was 67%; BRTO was successful in four of the patients in whom the inferior phrenic vein was the main draining vein, one of the patients in whom the pericardial vein was the main draining vein, and one of the patients in whom the paraesophageal vein was the main draining vein. In the other cases in which the inferior phrenic vein or pericardial vein was the main draining vein, BRTO could not be performed because of extravasation. In another patient in whom the paraesophageal vein was the main draining vein, the main draining pathway could not be identified at angiography because of a complicated azygos venous network. CONCLUSIONS: It is feasible to use BRTO to treat cases of gastric varices in which the inferior phrenic vein is the main draining vein. Cases in which the main draining pathway is the pericardial vein are less feasibile for BRTO. The use of BRTO in cases in which the paraesophageal vein is the main draining vein is possible but may be difficult because of a complicated venous network.

Time-resolved contrast-enhanced magnetic resonance digital subtraction angiography (MRDSA) in an infant with congenital pial arteriovenous fistula in the brain: a case report.

INTRODUCTION: Evaluation of the congenital vascular lesions of the brain requires multiple conventional intra-arterial digital subtraction angiographic examinations which have many associated risks including exposure to ionizing radiations. Magnetic resonance digital subtraction angiography is a non-invasive procedure with no related risks of radiation exposure. This technique can be of greater clinical significance in diagnosis and treatment planning of neurovascular abnormalities among children who are at far greater risk of invasive procedures like intra-arterial digital subtraction angiography. CASE REPORT: We report a congenital pial arteriovenous fistula in an infant which is a rare vascular lesion and has recently been identified as different from other vascular malformations. Magnetic resonance digital subtraction angiography provided hemodynamic information in absolute agreement with intra-arterial digital subtraction angiography indicating its significance in evaluating vascular lesions. DISCUSSION: Magnetic resonance digital subtraction angiography can be used in children in conjunction with intra-arterial digital subtraction angiography to minimize the cumulative radiation dose and multiple anesthesias.

[Dilation of subarachnoid space around the optic nerve in a patient with subdural effusion: a case report].

A fifty-year-old man who had a history of minor head injury a month previously presented with headache, visual disturbance and papilloedema. Brain MR imaging showed bilateral subdural effusion and fat saturated orbital MR imaging demonstrated dilated subarachnoid space around the optic nerve. The diameter of the subarachnoid space behind the globe was 7.0 mm and that of the optic nerve was 3.5 mm. Bilateral simple drainage was performed to prevent deterioration of the visual disturbance. Light bloody fluid with a subdural pressure of 10.5 cmH2O was drained from the burr hole at the left side, and colorless fluid was drained from the right. Orbital MR imaging during continuous drainage revealed shrinkage of the subarachnoid space around the optic nerve. However, follow-up MR imaging 5 months after drainage showed disappearance of the subdural effusion and the reappearance of the subarachnoid space around the optic nerve, even though the size was smaller than before surgery. These findings suggest that the diameter of the optic subarachnoid space co-relates with the intracranial pressure, and may be an indication for increased intracranial pressure.

Effect of intracranial pressure on the diameter of the optic nerve sheath.

OBJECT: The subarachnoid space around the optic nerve in the orbit can be visualized using T2-weighted MR imaging with the fat-saturation pulse sequence. The optic nerve sheath (ONS) diameter can be estimated by measuring the outer diameter of the subarachnoid space. Dilated ONS is associated with idiopathic intracranial hypertension and hydrocephalus, and is believed to reflect increased intracranial pressure (ICP). The relationship between dilated ONS and ICP is unclear because of the difficulty in obtaining noninvasive measurements of ICP. The authors investigated the relationship between subdural pressure measured at the time of surgery and ONS diameter measured on MR images in patients with chronic subdural fluid collection. METHODS: Twelve patients underwent bur-hole craniostomy with continuous drainage for chronic subdural hematoma or hygroma in 2006. Orbital thin-slice fat-saturated MR images were obtained before and after surgery, and the ONS diameters were measured just behind the optic globe. Subdural pressure was measured using a manometer before opening of the dura mater. RESULTS: A significant correlation was found between the ONS diameter and the subdural pressure (correlation coefficient 0.879, p = 0.0036). The ONS diameter before surgery (6.1 +/- 0.7 mm) was significantly reduced after surgery (4.8 +/- 0.9 mm, p = 0.003; measurements are expressed as the mean +/- standard deviation). CONCLUSIONS: Increased ONS diameter measured on coronal orbital thin-slice fat-saturated T2-weighted MR images is a strong indicator of increased ICP, and helps to differentiate between passive subdural fluid collection due to brain atrophy and subdural hygroma with increased ICP.

Cerebral vascular mean transit time in healthy humans: a comparative study with PET and dynamic susceptibility contrast-enhanced MRI.

Cerebral vascular mean transit time (MTT), defined as the ratio of cerebral blood volume to cerebral blood flow (CBV/CBF), is a valuable indicator of the cerebral circulation. Positron emission tomography (PET) and dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI) are useful for the quantitative determination of MTT in the clinical setting. The aim of this study was to establish a normal value set of MTT as determined by PET and by DSC-MRI and to identify differences between these methods. Seven healthy volunteers were studied with (15)O-PET (H(2)(15)O and C(15)O) and gradient-echo echo-planar DSC-MRI at 1.5 T. In the DSC-MRI study with bolus injection of contrast agent, deconvolution analysis was performed. Comparison of gray-to-white matter ratios showed fairly good agreement between PET and DSC-MRI for all parameters (relative CBV, relative CBF, and relative MTT), confirming the validity of relative measurements with DSC-MRI. However, quantitative MTT measured by DSC-MRI was significantly shorter than that measured by PET in cerebral cortical regions (2.8 to 3.0 secs for DSC-MRI versus 3.9 to 4.3 secs for PET) and the centrum semiovale (3.5 secs for DSC-MRI versus 4.8 secs for PET). These discrepancies may be because of the differences in the intrinsic sensitivity of each imaging modality to vascular components; whereas PET measurement of CBV is equally sensitive to all vascular components, measurement with DSC-MRI originates from the microvasculature in the vicinity of the brain parenchyma. This underlying difference may influence interpretation of MTT determined by PET or by DSC-MRI for patients with cerebrovascular disease.

Effect of regional tracer delay on CBF in healthy subjects measured with dynamic susceptibility contrast-enhanced MRI: comparison with 15O-PET.

PURPOSE: Deconvolution based on truncated singular value decomposition (SVD deconvolution) is a promising method for measuring cerebral blood flow (CBF) with dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI), but it has proved extremely sensitive to tracer delay. The purpose of this study was to investigate the effect of regional tracer delay on CBF determined by SVD deconvolution (SVD-CBF). SVD-CBFs with and without correction for the delay were compared with CBF measured by positron emission tomography (PET-CBF), which is regarded as the gold standard for quantification of CBF. METHODS: Perfusion MRI and PET were performed on seven healthy men. In the PET study, the CBF image was obtained with bolus injection of H2(15)O and continuous arterial sampling. In the DSC-MRI study with bolus injection of Gd-based contrast agent, dynamic perfusion data were obtained with a 1.5T scanner at 1-s intervals by means of gradient-echo echo-planar imaging. CBF was determined by the SVD deconvolution method with and without correction for the tracer delay. Region-of-interest measurements were obtained in the gray matter (cerebral cortex in the middle cerebral artery territory) and white matter (centrum semiovale). RESULTS: Tracer delay was significantly longer in white matter than in gray matter (1.45+/-0.61 s vs. 0.59+/-0.35 s, P<0.01). Correction for the delay increased SVD-CBF in the white matter and consequently reduced the gray-to-white SVD-CBF ratio. The uncorrected gray-to-white SVD-CBF ratio was significantly larger than that of PET-CBF (3.33+/-0.66 vs. 2.54+/-0.49, P<0.01). However, the gray-to-white delay-corrected SVD-CBF ratio did not differ significantly from that of PET-CBF (2.83+/-0.31 vs. 2.54+/-0.49, P=0.10). CONCLUSION: The tracer delay in DSC-MRI causes errors in CBF estimates, even in healthy persons, and therefore should be corrected for when delay-sensitive deconvolution, such as SVD deconvolution, is used.

T1-weighted fluid-attenuated inversion recovery at low field strength: a viable alternative for T1-weighted intracranial imaging.

BACKGROUND AND PURPOSE: T1-weighted spin-echo imaging has been widely used to study anatomic detail and abnormalities of the brain; however, the image contrast of this technique is often poor, especially at low field strengths. We tested a new pulse sequence, T1-weighted fluid-attenuated inversion recovery (FLAIR), which provides good contrast between lesions, surrounding edematous tissue, and normal parenchyma at low field strengths and at acquisition times comparable to those of T1-weighted spin-echo imaging. METHODS: Thirteen patients with brain lesions underwent T1-weighted spin-echo and T1-weighted FLAIR imaging during the same imaging session. T1-weighted spin-echo and T1-weighted FLAIR images were compared on the basis of four quantitative (lesion-white matter [WM] contrast-to-noise ratio [CNR], lesion-CSF CNR, gray matter-WM CNR, and WM-CSF CNR) and three qualitative criteria (conspicuousness of lesions, image artifacts, and overall image contrast). RESULTS: CNRs obtained with T1-weighted FLAIR were comparable but statistically superior to those obtained with T1-weighted spin-echo imaging. In general, T1-weighted FLAIR and T1-weighted spin-echo imaging produced comparable image artifacts. Conspicuousness of lesions and the overall image contrast were judged to be superior on T1-weighted FLAIR images. CONCLUSION: T1-weighted FLAIR imaging may be a valuable alternative to conventional T1-weighted imaging, because the former technique offers superior image contrast at low field strengths and comparable acquisition times.

MR-guided intravascular catheter manipulation: feasibility of both active and passive tracking in experimental study and initial clinical applications.

PURPOSE: To evaluate clinically the feasibility and usefulness of MR-guided intravascular procedures with either active or passive tracking. METHODS: With an active MR tacking system and a 0.2 Tesla open MR imager, real-time and biplane displays of positions of a receive-only coil at the tip of catheters were obtained. For passive tracking, 4 Fr catheters with suitable susceptibility for passive tracking were used. Passive tracking with a 1.5 Tesla MR imager could be performed with parameters of TR 15-50 msec, TE 2.2-2.7 msec, and FA 30 degrees. The temperature of each tracking catheter was monitored in vitro. Clinical trials were performed on six patients (three each). The catheter was introduced to the superior mesenteric artery (SMA) under MR guidance by active or passive tracking to perform MR imaging during arterial portography. RESULTS: The temperature increased minimally. In humans, the SMA and celiac artery could be easily introduced on active tracking. MR-guided manipulation of catheters by active or passive tracking in the model and in dogs' vessels was very successful. Introduction of the catheter into the SMA was successful in two cases of active tracking and in all cases of passive tracking. CONCLUSION: The MR-guided intravascular manipulation of catheters by active or passive tracking may be a clinically feasible method.

[Principles of diffusion-weighted MR imaging and application to clinical neurology].

Diffusion-weighted Imaging (DWI) is a advantageous method for early detection of cerebral ischemia. DWI with echo-planar sequence (EP-DWI) offers multisectional images sensitive to cytotoxic edema in a very short aquisition time and is almost free from motion artifact. However, the susceptibility artifacts and low spatial resolution of EP-DWI must be improved. In estimation of DWI, influence of T2 must be considered, because DWI is almost always based on T2-weighted imaging. DWI is applied to other cerebral disorders such as degenerative and demyelinating disease, infectious disease, tumors or so. In order to demonstrate water diffusion precisely, diffusion tensor imaging (DTI) must be introduced and applied to anisotropy indices such as fractional anisotropy (FA) and depiction of neurofiber direction, tractography. Measurements of FA in various degenerative diseases may contribute to differentiation in normal appearing white matter. Diffusion tensor tractography may provide more information about relationship of major white matter tract such as corticospinal tract with brain lesion. Furthermore, DWI and DTI are expected to demonstrate diffusion of protons of aminoacids such as choline, creatine, NAA and provide more pertinent information of regional pathologic state of the brain in future.

A rare case of focal multiple medullary venous malformations with ipsilateral cerebral surface varix.

We report here a rare case of focal multiple venous malformations (VMs) in the white matter, via a draining vein arising from each VM, connecting with an ipsilateral cerebral surface venous varix. The male teen was asymptomatic neurologically. A diagnostic process using of MRI/MRDSA in this extremely rare entity is important as the more incidental discovery is expected with increasing opportunities of performing brain CT/MRI for various indications.

Basi-parallel anatomical scanning (BPAS)-MRI can improve discrimination of vertebral artery dissection from atherosclerosis and hypoplasia.

RATIONALE AND OBJECTIVES: The purpose of this study was to determine the effectiveness of combining basi-parallel anatomic scanning (BPAS)-magnetic resonance (MR) imaging findings with those of time-of-flight (TOF)-MR angiography (MRA) for differentiating vertebral artery dissection (VAD) from other causes of true artery narrowing such as atherosclerosis or an anatomical variation such as vertebral artery hypoplasia. MATERIALS AND METHODS: Fifteen cases of VAD, 15 of atherosclerotic narrowing, and 8 of hypoplastic vertebral arteries were retrospectively selected for this study. Conventional MR sequences (T1WI, T2WI, and T2*WI, fluid attenuation inversion recovery, TOF-MRA) and BPAS images were analyzed by two readers blinded to the patients' clinical data and history. Receiver operating characteristic analyses were performed to compare the diagnostic capability of conventional MR sequences with and without BPAS imaging in suspected VAD cases. RESULTS: The area under the curve increased significantly by combining BPAS imaging findings with those of conventional MRI (0.72 vs. 0.96 and 0.81 vs. 0.99; P = .0022 and P = .0068, respectively, for readers 1 and 2). In addition, the sensitivity was 100% (15/15) for both readers and significantly greater than that of conventional MRI (53.3% [8/15] for both readers, P = .0156); however, specificities were not significantly different (82.6% [19/23] vs. 82.6% [19/23] and 91.33% [21/23] vs. 95.7% [22/23]). The interobserver agreement also improved by adding BPAS imaging. CONCLUSIONS: Adding BPAS imaging to conventional MRI and MRA sequences can improve diagnostic capability and sensitivity in suspected VAD cases and be helpful in differentiating it from other causes of vertebral artery narrowing such as atherosclerosis or hypoplasia.

High b-value q-space analyzed diffusion-weighted MRI using 1.5 tesla clinical scanner; determination of displacement parameters in the brains of normal versus multiple sclerosis and low-grade glioma subjects.

PURPOSE: We aimed to determine the displacement parameters in the brains of normal individuals relative to brain parenchymal abnormalities, such as multiple sclerosis (MS) and low-grade glioma, by q-space imaging (QSI) using 1.5-T magnetic resonance (MR) scanner. MATERIALS AND METHODS: Thirty-five normal, three pathologically proven low-grade glioma, and five MS subjects were imaged by a 1.5-T MR unit for QSI (b-values, 0-12,000 s/mm(2)). Mean displacement (MD) values in white matter (WM), gray matter (GM), and lateral ventricle (cerebrospinal fluid [CSF]) of normal subjects, plaques, and normal appearing WM (NAWM) of MS subjects and glioma lesions were calculated. Mann-Whitney U test was used for comparison. RESULTS: In normal subjects, MD values were 6.6 ± 0.2, 8.44 ± 0.41, and 17.08 ± 0.80 µm for WM, GM, and CSF, respectively, while those for NAWM and WM plaques in MS, and glioma lesions were significantly higher at 7.0 ± 0.17, 9.3 ± 2.3, and 9.6 ± 0.40 µm, respectively, compared to WM in normal subjects. CONCLUSION: We propose that the relative values of MD obtained by QSI in control and diseased tissues can be useful for diagnosing various WM abnormalities.

A comparison of mean displacement values using high b-value Q-space diffusion-weighted MRI with conventional apparent diffusion coefficients in patients with stroke.

RATIONALE AND OBJECTIVES: Q-space analysis using high b-value diffusion-weighted magnetic resonance (MR) data provides information on tissue microstructure in contrast to conventional MR imaging (MRI) based on low b-value diffusion-weighted imaging (DWI). The purpose of this study was to evaluate the use of mean displacement (MDP) map in stroke patients using q-space diffusion-weighted MRI (QSI). MATERIALS AND METHODS: Twenty-one patients presenting with a total of 22 acute or subacute cerebral infarctions were included. MR protocol consisted of conventional MR sequences, DWI (b-value; 1000 s/mm(2)) and QSI (b-value; maximum 12,000 s/mm(2)). Apparent diffusion coefficient (ADC) maps of conventional DWI and MDP maps of QSI data were obtained and compared in the ischemic lesions and corresponding normal tissues. RESULTS: Decreased ADC values were present in all lesions. There was no correlation between ADC and MDP values in the lesions (r = 0.21). MDP values of the lesions were 8.60 ± 1.26 µm (mean ± SD). Most of the lesions (16/22) had higher MDP values than normal brain tissue. Three lesions showed lower MDP values and three showed mixed MDP values. CONCLUSIONS: The MDP maps using QSI data provides additional information for stroke patients compared to conventional DWI.