Fluid-attenuated inversion recovery vascular hyperintensities in predicting cerebral hyperperfusion after intracranial arterial stenting

Purpose

No reliable imaging sign predicting cerebral hyperperfusion after intracranial arterial stenting (IAS) had been described in the literature. This study evaluated the effect of fluid-attenuated inversion recovery vascular hyperintensities (FVHs), also called hyperintense vessel sign on T2-weighted fluid-attenuated inversion recovery (T2-FLAIR) MR images, in predicting significant increase in cerebral blood flow (CBF) defined by arterial spin labeling (ASL) after IAS.

Methods

We reviewed ASL CBF images and T2-FLAIR MR images before (D0), 1 day after (D1), and 3 days after (D3) IAS of 16 patients. T1-weighted MR images were used as cerebral maps for calculating CBF. The changes in CBF values after IAS were calculated in and compared among stenting and nonstenting vascular territories. An increase more than 50% of CBF was considered as hyperperfusion. The effect of FVHs in predicting hyperperfusion was calculated.

Results

The D1 CBF value was significantly higher than the D0 CBF value in stenting vascular, contralateral anterior cerebral artery, contralateral middle cerebral artery, and contralateral posterior cerebral artery (PCA) territories (all P < .05). The D1 and D3 CBF values were significantly higher than the D0 CBF value in overall vascular (P < .001), overall nonstenting vascular (P < .001), and ipsilateral PCA (P < .05) territories. The rate of more than 50% increases in CBF was significantly higher in patients who exhibited asymmetric FVHs than in those who did not exhibit these findings.

Conclusion

FVHs could be a critical predictor of a significant increase in CBF after IAS.

     

Comparative study of pulsed-continuous arterial spin labeling and dynamic susceptibility contrast imaging by histogram analysis in evaluation of glial tumors

Purpose

Arterial spin labeling (ASL) is a non-invasive perfusion technique that may be an alternative to dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) for assessment of brain tumors. To our knowledge, there have been no reports on histogram analysis of ASL. The purpose of this study was to determine whether ASL is comparable with DSC-MRI in terms of differentiating high-grade and low-grade gliomas by evaluating the histogram analysis of cerebral blood flow (CBF) in the entire tumor.

Methods

Thirty-four patients with pathologically proven glioma underwent ASL and DSC-MRI. High-signal areas on contrast-enhanced T₁-weighted images or high-intensity areas on fluid-attenuated inversion recovery images were designated as the volumes of interest (VOIs). ASL-CBF, DSC-CBF, and DSC-cerebral blood volume maps were constructed and co-registered to the VOI. Perfusion histogram analyses of the whole VOI and statistical analyses were performed to compare the ASL and DSC images.

Results

There was no significant difference in the mean values for any of the histogram metrics in both of the low-grade gliomas (n?=?15) and the high-grade gliomas (n?=?19). Strong correlations were seen in the 75th percentile, mean, median, and standard deviation values between the ASL and DSC images. The area under the curve values tended to be greater for the DSC images than for the ASL images.

Conclusions

DSC-MRI is superior to ASL for distinguishing high-grade from low-grade glioma. ASL could be an alternative evaluation method when DSC-MRI cannot be used, e.g., in patients with renal failure, those in whom repeated examination is required, and in children.

     

Cerebral blood flow,transit time,and apparent diffusion coefficient in moyamoya disease before and after acetazolamide

Introduction

The goal of this study was to assess the changes in arterial spin labeling (ASL) cerebral blood flow (CBF) and arterial transit time (ATT), and in apparent diffusion coefficient (ADC), before and after an acetazolamide challenge in moyamoya patients, as function of arterial stenosis severity.

Methods

Pre-operative patients diagnosed with moyamoya disease who could undergo MRI at 3.0T were recruited for this study. A multi-delay pseudo-continuous ASL and a diffusion-weighted sequence were acquired before and 15 min after acetazolamide injection. The severity of anterior, middle, and posterior cerebral artery pathology was graded on time-of-flight MR angiographic images. CBF, ATT, and ADC were measured on standardized regions of interest as function of the vessel stenosis severity.

Results

Thirty patients were included. Fifty-four percent of all vessels were normal, 28% mildly/moderately stenosed, and 18% severely stenosed/occluded. Post-acetazolamide, a significantly larger CBF (ml/100 g/min) increase was observed in territories of normal (+19.6 ± 14.9) compared to mildly/moderately stenosed (+14.2 ± 27.2, p = 0.007), and severely stenosed/occluded arteries (+9.9 ± 24.2, p < 0.0001). ATT was longer in territories of vessel anomalies compared with normal regions at baseline. ATT decreases were observed in all territories post-acetazolamide. ADC did not decrease after acetazolamide in any regions, and no correlation was found between ADC changes and baseline ATT, change in ATT, or CVR.

Conclusion

The hemodynamic response in moyamoya disease, as measured with ASL CBF, is impaired mostly in territories with severe arterial stenosis/occlusion, while ATT was prolonged in all non-normal regions. No significant changes in ADC were observed after acetazolamide.

     

Whole-tumor histogram analysis of the cerebral blood volume map: tumor volume defined by 11C-methionine positron emission tomography image improves the diagnostic accuracy of cerebral glioma grading

Purpose

This study aimed to compare the tumor volume definition using conventional magnetic resonance (MR) and 11C-methionine positron emission tomography (MET/PET) images in the differentiation of the pre-operative glioma grade by using whole-tumor histogram analysis of normalized cerebral blood volume (nCBV) maps.

Materials and methods

Thirty-four patients with histopathologically proven primary brain low-grade gliomas (n = 15) and high-grade gliomas (n = 19) underwent pre-operative or pre-biopsy MET/PET, fluid-attenuated inversion recovery, dynamic susceptibility contrast perfusion-weighted magnetic resonance imaging, and contrast-enhanced T1-weighted at 3.0 T. The histogram distribution derived from the nCBV maps was obtained by co-registering the whole tumor volume delineated on conventional MR or MET/PET images, and eight histogram parameters were assessed.

Results

The mean nCBV value had the highest AUC value (0.906) based on MET/PET images. Diagnostic accuracy significantly improved when the tumor volume was measured from MET/PET images compared with conventional MR images for the parameters of mean, 50th, and 75th percentile nCBV value (p = 0.0246, 0.0223, and 0.0150, respectively).

Conclusion

Whole-tumor histogram analysis of CBV map provides more valuable histogram parameters and increases diagnostic accuracy in the differentiation of pre-operative cerebral gliomas when the tumor volume is derived from MET/PET images.

     

Apparent brain temperature imaging with multi-voxel proton magnetic resonance spectroscopy compared with cerebral blood flow and metabolism imaging on positron emission tomography in patients with unilateral chronic major cerebral artery steno-occlusive disease

Purpose

The purpose of the present study was to determine whether apparent brain temperature imaging using multi-voxel proton magnetic resonance (MR) spectroscopy correlates with cerebral blood flow (CBF) and metabolism imaging in the deep white matter of patients with unilateral chronic major cerebral artery steno-occlusive disease.

Methods

Apparent brain temperature and CBF and metabolism imaging were measured using proton MR spectroscopy and ¹⁵O-positron emission tomography (PET), respectively, in 35 patients. A set of regions of interest (ROIs) of 5 × 5 voxels was placed on an MR image so that the voxel row at each edge was located in the deep white matter of the centrum semiovale in each cerebral hemisphere. PET images were co-registered with MR images with these ROIs and were re-sliced automatically using image analysis software.

Results

In 175 voxel pairs located in the deep white matter, the brain temperature difference (affected hemisphere ? contralateral hemisphere: ΔBT) was correlated with cerebral blood volume (CBV) (r = 0.570) and oxygen extraction fraction (OEF) ratios (affected hemisphere/contralateral hemisphere) (r = 0.641). We excluded voxels that contained ischemic lesions or cerebrospinal fluid and calculated the mean values of voxel pairs in each patient. The mean ΔBT was correlated with the mean CBF (r = ? 0.376), mean CBV (r = 0.702), and mean OEF ratio (r = 0.774).

Conclusions

Apparent brain temperature imaging using multi-voxel proton MR spectroscopy was correlated with CBF and metabolism imaging in the deep white matter of patients with unilateral major cerebral artery steno-occlusive disease.

     

Pathological factors contributing to crossed cerebellar diaschisis in cerebral gliomas: a study combining perfusion,diffusion, and structural MR imaging

Purpose

To investigate imaging features of crossed cerebellar diaschisis (CCD) in cerebral gliomas, and its underlying pathophysiological mechanisms.

Methods

Thirty-three pre-surgical patients with cerebral gliomas and 33 healthy controls underwent arterial spin-labeling, diffusion tensor imaging, and high-resolution T1-weighted imaging using MRI, in order to estimate cerebral blood flow (CBF), white matter integrity, and lesion volume, respectively. Asymmetry indices of CBF in the cerebellum were used for evaluating the level of CCD in the patients. These indices were correlated with clinical variables (lesion size and position, tumor histological grade, and CBF asymmetry) and diffusion tensor imaging parameters (fractional anisotropy and number of fibers in the cortico-ponto-cerebellar pathway and across the cerebral hemispheres), respectively.

Results

The patients showed decreased CBF in the cerebellar hemisphere contralateral to the supratentorial tumor, and increased CBF asymmetry in the cerebellum (both P?<?0.05). CCD levels in high-grade gliomas were higher than those of low-grade gliomas (P?<?0.05). CCD levels were negatively correlated with the size of the supratentorial lesions, and positively correlated with FA asymmetry in the cerebral fibers (both P?<?0.05).

Conclusions

CCD in cerebral gliomas was specifically associated with tumor histological grade, lesion size, and white matter impairments in the hemisphere ipsilateral to the tumor. The findings implicated that observing CCD might have potential for assisting grading diagnosis of cerebral gliomas.

     

Grading diffuse gliomas without intense contrast enhancement by amide proton transfer MR imaging: comparisons with diffusion- and perfusion-weighted imaging

Objectives

To investigate whether amide proton transfer (APT) MR imaging can differentiate high-grade gliomas (HGGs) from low-grade gliomas (LGGs) among gliomas without intense contrast enhancement (CE).

Methods

This retrospective study evaluated 34 patients (22 males, 12 females; age 36.0?±?11.3 years) including 20 with LGGs and 14 with HGGs, all scanned on a 3T MR scanner. Only tumours without intense CE were included. Two neuroradiologists independently performed histogram analyses to measure the 90th-percentile (APT₉₀) and mean (APT_mean) of the tumours’ APT signals. The apparent diffusion coefficient (ADC) and relative cerebral blood volume (rCBV) were also measured. The parameters were compared between the groups with Student’s t-test. Diagnostic performance was evaluated with receiver operating characteristic (ROC) analysis.

Results

The APT₉₀ (2.80?±?0.59 % in LGGs, 3.72?±?0.89 in HGGs, P?=?0.001) and APT_mean (1.87?±?0.49 % in LGGs, 2.70?±?0.58 in HGGs, P?=?0.0001) were significantly larger in the HGGs compared to the LGGs. The ADC and rCBV values were not significantly different between the groups. Both the APT₉₀ and APT_mean showed medium diagnostic performance in this discrimination.

Conclusions

APT imaging is useful in discriminating HGGs from LGGs among diffuse gliomas without intense CE.

Key Points

? Amide proton transfer (APT) imaging helps in grading non-enhancing gliomas ? High-grade gliomas showed higher APT signal than low-grade gliomas ? APT imaging showed better diagnostic performance than diffusion- and perfusion-weighted imaging

     

Early quantitative CT perfusion parameters variation for prediction of delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage

Objectives

To prospectively evaluate the predictive value of cerebral perfusion–computerized tomography (CTP) parameters variation between day0 and day4 after aneurysmal subarachnoid haemorrhage (aSAH).

Methods

Mean transit time (MTT) and cerebral blood flow (CBF) values were compared between patients with delayed cerebral ischemia (DCI+ group) and patients without DCI (DCI- group) for previously published optimal cutoff values and for variations of MTT (ΔMTT) and of CBF (ΔCBF) values between day0 and day4. DCI+ was defined as a cerebral infarction on 3-months follow-up MRI.

Results

Among 47 included patients, 10 suffered DCI+. Published optimal cutoff values did not predict DCI, either at day0 or at day4. Conversely, ΔMTT and ΔCBF significantly differed between the DCI+ and DCI- groups, with optimal ΔMTT and ΔCBF values of 0.91 seconds (83.9 % sensitivity, 79.5 % specificity, AUC 0.84) and -7.6 mL/100 g/min (100 % sensitivity, 71.4 % specificity, AUC 0.86), respectively. In multivariate analysis, ΔCBF (OR?=?1.91, IC95% 1.13–3.23 per each 20 % decrease of ΔCBF) and ΔMTT values (OR?=?14.70, IC95% 4.85–44.52 per each 20 % increase of ΔMTT) were independent predictors of DCI.

Conclusions

Assessment of MTT and CBF value variations between day0 and day4 may serve as an early imaging surrogate for prediction of DCI in aSAH.

Key points

? CT perfusion values are an imaging surrogate for prediction of DCI.? Early variations (day0–day4) after aneurysmal subarachnoid haemorrhage predicted DCI.? A CBF decrease of 7.6 mL/min/100 g predicted DCI with 100?% sensitivity.? An MTT increase of 0.91 seconds predicted DCI with 83.9?% sensitivity.? DCI risk multiplied by 2 per 20?% ΔCBF decrease and by 15 per 20?% ΔMTT increase.

     

MR-guided percutaneous biopsy of solitary pulmonary lesions using a 1.0-T open high-field MRI scanner with respiratory gating

Objectives

To prospectively evaluate the feasibility, safety and accuracy of MR-guided percutaneous biopsy of solitary pulmonary lesions using a 1.0-T open MR scanner with respiratory gating.

Methods

Sixty-five patients with 65 solitary pulmonary lesions underwent MR-guided percutaneous coaxial cutting needle biopsy using a 1.0-T open MR scanner with respiratory gating. Lesions were divided into two groups according to maximum lesion diameters: ≤2.0 cm (n?=?31) and >2.0 cm (n?=?34). The final diagnosis was established in surgery and subsequent histology. Diagnostic accuracy, sensitivity and specificity were compared between the groups using Fisher’s exact test.

Results

Accuracy, sensitivity and specificity of MRI-guided percutaneous pulmonary biopsy in diagnosing malignancy were 96.9 %, 96.4 % and 100 %, respectively. Accuracy, sensitivity and specificity were 96.8 %, 96.3 % and 100 % for lesions 2.0 cm or smaller and 97.1 %, 96.4 % and 100 %, respectively, for lesions larger than 2.0 cm. There was no significant difference between the two groups (P?>?0.05). Biopsy-induced complications encountered were pneumothorax in 12.3 % (8/65) and haemoptysis in 4.6 % (3/65). There were no serious complications.

Conclusions

MRI-guided percutaneous biopsy using a 1.0-T open MR scanner with respiratory gating is an accurate and safe diagnostic technique in evaluation of pulmonary lesions.

Key Points

? MRI-guided percutaneous lung biopsy using a 1.0-T open MR scanner is feasibility. ? 96.9 % differentiation accuracy of malignant and benign lung lesions is possible. ? No serious complications occurred in MRI-guided lung biopsy.

     

Complication rates of CT-guided transthoracic lung biopsy: meta-analysis

Objectives

To meta-analyze complication rate in computed tomography (CT)-guided transthoracic lung biopsy and associated risk factors.

Methods

Four databases were searched from 1/2000 to 8/2015 for studies reporting complications in CT-guided lung biopsy. Overall and major complication rates were pooled and compared between core biopsy and fine needle aspiration (FNA) using the random-effects model. Risk factors for complications in core biopsy and FNA were identified in meta-regression analysis.

Results

For core biopsy, 32 articles (8,133 procedures) were included and for FNA, 17 (4,620 procedures). Pooled overall complication rates for core biopsy and FNA were 38.8 % (95 % CI: 34.3–43.5 %) and 24.0 % (95 % CI: 18.2–30.8 %), respectively. Major complication rates were 5.7 % (95 % CI: 4.4–7.4 %) and 4.4 % (95 % CI: 2.7–7.0 %), respectively. Overall complication rate was higher for core biopsy compared to FNA (p?<?0.001). For FNA, larger needle diameter was a risk factor for overall complications, and increased traversed lung parenchyma and smaller lesion size were risk factors for major complications. For core biopsy, no significant risk factors were identified.

Conclusions

In CT-guided lung biopsy, minor complications were common and occurred more often in core biopsy than FNA. Major complication rate was low. For FNA, smaller nodule diameter, larger needle diameter and increased traversed lung parenchyma were risk factors for complications.

Key Points

? Minor complications are common in CT-guided lung biopsy ? Major complication rate is low in CT-guided lung biopsy ? CT-guided lung biopsy complications occur more often in core biopsy than FNA ? Major complication rate is similar in core biopsy and FNA ? Risk factors for FNA are larger needle diameter, smaller lesion size

     

Pediatric astrocytic tumor grading: comparison between arterial spin labeling and dynamic susceptibility contrast MRI perfusion

Purpose

The aim of this study was to compare arterial spin labeling (ASL) and dynamic susceptibility contrast (DSC) MRI perfusion with respect to diagnostic performance in tumor grading in pediatric patients with low- and high-grade astrocytic tumors (AT).

Methods

We retrospectively analyzed 37 children with histologically proven treatment naive low- and high-grade AT who underwent concomitant pre-operative ASL and DSC MRI perfusion. Studies were performed on a 1.5 T scanner, and a pulsed technique was used for ASL. DSC data were post-processed with a leakage correction software. Normalization of tumor perfusion parameters was performed with contralateral normal appearing gray matter. Normalized cerebral blood volume (nCBV) values in the most perfused area of each neoplasm were compared with normalized DSC-derived cerebral blood flow (nDSC-CBF) and ASL-derived cerebral blood flow (nASL-CBF) data, and correlated with WHO tumor grade. Statistics included Pearson’s chi-square and Mann-Whitney U tests, Spearman’s rank correlation, and receiver operating characteristic (ROC) analysis.

Results

A significant correlation was demonstrated between DSC and ASL data (p?<?0.001). Significant differences in terms of DSC and ASL data were found between low- and high-grade AT (p?<?0.001). ROC analysis demonstrated similar performances between all parameters in predicting tumor grade (nCBV: AUC 0.96, p?<?0.001; nDSC-CBF: AUC 0.98, p?<?0.001; nASL-CBF: AUC 0.96, p?<?0.001).

Conclusions

Normalized pulsed ASL performed with a 1.5 T scanner provides comparable results to DSC MRI perfusion in pediatric AT and may allow distinction between high- and low-grade AT.

     

Cerebral blood flow and metabolism associated with cerebral microbleeds in small vessel disease

Objective

Cerebral microbleeds (CMBs), probably reflecting microangiopathy, have not yet sufficiently been examined in association with cerebral blood flow (CBF) and metabolism. We investigated the relationships between CMBs, and CBF and metabolism in symptomatic small vessel disease.

Methods

We enrolled 22 patients with symptomatic small vessel disease without severe stenosis (>50 %) in major cerebral arteries. Volumes of white matter lesions (WMLs) and number of CMBs were assessed on images of fluid-attenuated inversion recovery and gradient-echo T2*-weighted magnetic resonance imaging, respectively. Patients were divided into two groups according to the median number of CMBs (group I <5, n = 10; group II ≥5, n = 12). Parametric images of CBF, cerebral metabolic rate of oxygen (CMRO₂), oxygen extraction fraction and cerebral blood volume were estimated using positron emission tomography and ¹⁵O-labeled gases. The functional values in the cortex–subcortex, basal ganglia, and centrum semiovale were compared between the two groups.

Results

Volumes of WMLs of group II were larger than those of group I (median: 38.4; range: 25.1–91.5 mL vs. median: 11.3; range: 4.2–73.4 mL, p = 0.01). In the centrum semiovale, the mean CBF of group II was significantly lower than that of group I (12.6 ± 2.6 vs. 15.6 ± 3.3 mL/100 g/min, p = 0.04). In the other regions, there were no significant differences in either CBF or CMRO₂ between the two groups.

Conclusions

Our study indicated that increases in the number of CMBs with larger volumes of WMLs were associated with cerebral ischemia in the deep white matter in patients with symptomatic small vessel disease.

     

Pneumothorax with prolonged chest tube requirement after CT-guided percutaneous lung biopsy: incidence and risk factors

Purpose

To evaluate the incidence and risk factors of pneumothoraces requiring prolonged maintenance of a chest tube following CT-guided percutaneous lung biopsy in a retrospective, single-centre case series.

Materials and methods

All patients undergoing CT-guided percutaneous lung biopsies between June 2012 and May 2014 who required chest tube insertion for symptomatic or enlarging pneumothoraces were identified. Based on chest tube dwell time, patients were divided into two groups: short term (0-2 days) or prolonged (3 or more days). The following risk factors were stratified between groups: patient demographics, target lesion characteristics, and procedural/periprocedural technique and outcomes.

Results

A total of 2337 patients underwent lung biopsy; 543 developed pneumothorax (23.2 %), 187 required chest tube placement (8.0 %), and 55 required a chest tube for 3 days or more (2.9 % of all biopsies, 29.9 % of all chest tubes). The median chest tube dwell time for short-term and prolonged groups was 1.0 days and 4.7 days, respectively. The transfissural needle path predicted prolonged chest tube requirement (OR: 2.5; p?=?0.023). Other factors were not significantly different between groups.

Conclusion

Of patients undergoing CT-guided lung biopsy, 2.9 % required a chest tube for 3 or more days. Transfissural needle path during biopsy was a risk factor for prolonged chest tube requirement.

Key Points

? CT-guided percutaneous lung biopsy (CPLB) is an important method for diagnosing lung lesions ? A total of 2.9 % of patients require a chest tube for ≥3 days following CPLB ? Transfissural needle path is a risk factor for prolonged chest tube time

     

Information of prostate biopsy positive core: does it affect MR detection of prostate cancer on using 3T-MRI?

Objective

We assessed which information from a prostate biopsy had the strongest relationship with prostate cancer detection by 3T-MRI.

Materials and methods

Sixty-one consecutive patients with biopsy-proven prostate cancer who underwent 3T-MRI before biopsy were enrolled in this retrospective study. Two radiologists independently reviewed T2-weighted and diffusion-weighted images. When the cancer lesions were revealed by biopsy and MRI depicted them at corresponding sites, we classified these lesions as MRI-detectable cancer. If the cancer lesions were revealed by biopsy, but any cancers had not been detected, we classified these lesions as MRI-undetectable cancer. We compared the Gleason score (GS), cancer ratio (CaR) and cancer length (CaL) from core biopsies between the two groups.

The results

GS, CaR and CaL differed significantly between the MRI-detectable group (N = 70), and the MRI-undetectable group (N = 73). 3T-MRI could detect cancer cores with a sensitivity of 90.5 % in cores with CaR ≥ 60 %, and with a sensitivity of 81.8 % in those with CaL ≥ 5 mm. Receiver operating characteristic analysis showed that CaR (P = 0.006) and CaL (P = 0.010) significantly associated with the prostate cancer detection using MRI rather than GS.

Conclusion

CaR and CaL from the core biopsies showed a stronger relationship to detection of the prostate cancer on 3T-MRI than the GS did.

     

Effect of resolution recovery using graph plots on regional cerebral blood flow in healthy volunteers

Purpose

We evaluated the effect of resolution recovery (RR) using graph plots on regional cerebral blood flow (rCBF) in brain perfusion single-photon emission computed tomography (SPECT) images derived from healthy volunteers and patients diagnosed with probable Alzheimer’s disease.

Method

We acquired brain perfusion SPECT images with scatter correction (SC), computed tomography-based attenuation correction (CTAC), and RR from a three-dimensional brain phantom and from healthy volunteers. We then compared contrast-to-noise ratio, count density ratios, increase maps, and rCBF using statistical parametric mapping 8.

Results

Regional brain counts were significantly increased from 20–24% with SC, CTAC, and RR compared with SC and CTAC. Mean CBF in healthy volunteers was 42.5 ± 5.4 mL/100 g/min. Average rCBF determined using SC, CTAC and RR increased 7.5, 2.0, and 3.7% at the thalamus, posterior cingulate, and whole brain, respectively, compared with SC and CTAC.

Conclusion

Resolution recovery caused variations in normal rCBF because counts increased in cerebral regions.

     

Imaging of cerebral ischemic edema and neuronal death

Purpose

In acute cerebral ischemia, the assessment of irreversible injury is crucial for treatment decisions and the patient’s prognosis. There is still uncertainty how imaging can safely differentiate reversible from irreversible ischemic brain tissue in the acute phase of stroke.

Methods

We have searched PubMed and Google Scholar for experimental and clinical papers describing the pathology and pathophysiology of cerebral ischemia under controlled conditions.

Results

Within the first 6 h of stroke onset, ischemic cell injury is subtle and hard to recognize under the microscope. Functional impairment is obvious, but can be induced by ischemic blood flow allowing recovery with flow restoration. The critical cerebral blood flow (CBF) threshold for irreversible injury is ~15 ml/100 g × min. Below this threshold, ischemic brain tissue takes up water in case of any residual capillary flow (ionic edema). Because tissue water content is linearly related to X-ray attenuation, computed tomography (CT) can detect and measure ionic edema and, thus, determine ischemic brain infarction. In contrast, diffusion-weighted magnetic resonance imaging (DWI) detects cytotoxic edema that develops at higher thresholds of ischemic CBF and is thus highly sensitive for milder levels of brain ischemia, but not specific for irreversible brain tissue injury.

Conclusion

CT and MRI are complimentary in the detection of ischemic stroke pathology and are valuable for treatment decisions.

     

Incidentally detected enhancing lesions found in breast MRI: analysis of apparent diffusion coefficient and T2 signal intensity significantly improves specificity

Objectives

To evaluate the value of adding T2- and diffusion-weighted imaging (DWI) to the BI-RADS® classification in MRI-detected lesions.

Methods

This retrospective study included 112 consecutive patients who underwent 3.0T structural breast MRI with T2- and DWI on the basis of EUSOMA recommendations. Morphological and kinetic features, T2 signal intensity (T2 SI) and apparent diffusion coefficient (ADC) findings were assessed.

Results

Thirty-three (29.5 %) patients (mean age 57.0?±?12.7 years) had 36 primarily MRI-detected incidental lesions of which 16 (44.4 %) proved to be malignant. No single morphological or kinetic feature was associated with malignancy. Both low T2 SI (P?=?0.009) and low ADC values (≤0.87?×?10^?3 mm²s^?1, P?<?0.001) yielded high specificity (80.0 %/80.0 %). The BI-RADS classification supplemented with information from DWI and T2-WI improved the diagnostic performance of the BI-RADS classification as sensitivity remained 100 % and specificity improved from 30 % to 65.0 %. The numbers of false positive lesions declined from 39 % (N?=?14) to 19 % (N?=?7).

Conclusion

MRI-detected incidental lesions may be challenging to characterize as they have few specific malignancy indicating features. The specificity of MRI can be improved by incorporating T2 SI and ADC values into the BI-RADS assessment.

Key Points

? MRI-detected incidental lesions have few specific malignancy indicating features. ? ≥ 1 suspicious morphologic or kinetic feature may warrant biopsy. ? T2 signal intensity and DWI assessment are feasible in primarily MRI-detected lesions. ? T2 SI and DWI assessment improve the BI-RADS specificity in MRI-detected lesions.

     

Assessment of brain temperatures during different phases of the menstrual cycle using diffusion-weighted imaging thermometry

Purpose

To investigate changes in brain temperature according to the menstrual cycle in women using diffusion-weighted imaging (DWI) thermometry and to clarify relationships between brain and body temperatures.

Materials and methods

In 20 healthy female volunteers (21.3–38.8 years), DWI of the brain was performed during the follicular and luteal phases to calculate the brain temperature. During DWI, body temperatures were also measured. Group comparisons of each temperature between the two phases were performed using the paired t test. Correlations between brain and body temperatures were analyzed using Pearson’s correlation coefficient test.

Results

Mean diffusion-based brain temperature was 36.24 °C (follicular) and 36.96 °C (luteal), showing a significant difference (P < 0.0001). Significant differences were also seen for each body temperature between the two phases. Correlation coefficients between diffusion-based brain and each body temperature were r = 0.2441 (P = 0.1291), –0.0332 (0.8387), and –0.0462 (0.7769), respectively.

Conclusions

In women of childbearing age, brain and body temperatures appear significantly higher in the luteal than in the follicular phase. However, brain and body temperatures show no significant correlations.

     

Recurrence patterns of glioblastoma treated with postoperative radiation therapy: relationship between extent of resection and progression-free interval

Purpose

To evaluate progression pattern and progression-free interval for patients with glioblastoma multiforme (GBM), on the basis of the extent of resection.

Materials and methods

Between January 2000 and September 2009, 138 patients with GBM underwent postoperative radiation therapy and longitudinal magnetic resonance imaging studies. The operations were classified as biopsy, partial resection (PR), and gross total resection (GTR). Progression patterns were classified as gross tumor volume (GTV), T2 hyperintensity (T2h), distant, and free. We used the Kruskal–Wallis test to compare progression-free intervals on the basis of the extent of resection and the progression pattern.

Results

Recurrence of biopsied and PR tumors at the GTV site was 100 and 97%, respectively. The median progression-free interval was 3 months for biopsied (n = 29), 4 months for PR (n = 70), and 8 months for GTR (n = 39) tumors (p < 0.05). The median progression-free interval for progression patterns classified as GTV (n = 97), T2h (n = 24), distant (n = 12), and free (n = 5) was 3 (p < 0.05), 7, 8, and 29 months, respectively.

Conclusion

Control of the GTV can increase the progression-free interval because gross residual tumors progress earlier than infiltrating tumor cells do.

     

Differentiation of grade II/III and grade IV glioma by combining “T1 contrast-enhanced brain perfusion imaging” and susceptibility-weighted quantitative imaging

Purpose

MRI is a useful method for discriminating low- and high-grade glioma using perfusion MRI and susceptibility-weighted imaging (SWI). The purpose of this study is to evaluate the usefulness of T1-perfusion MRI and SWI in discriminating among grade II, III, and IV gliomas.

Methods

T1-perfusion MRI was used to measure relative cerebral blood volume (rCBV) in 129 patients with glioma (70 grade IV, 33 grade III, and 26 grade II tumors). SWI was also used to measure the intratumoral susceptibility signal intensity (ITSS) scores for each tumor in these patients. rCBV and ITSS values were compared to seek differences between grade II vs. grade III, grade III vs. grade IV, and grade III+II vs. grade IV tumors.

Results

Significant differences in rCBV values of the three grades of the tumors were noted and pairwise comparisons showed significantly higher rCBV values in grade IV tumors as compared to grade III tumors, and similarly increased rCBV was seen in the grade III tumors as compared to grade II tumors (p < 0.001). Grade IV gliomas showed significantly higher ITSS scores on SWI as compared to grade III tumors (p < 0.001) whereas insignificant difference was seen on comparing ITSS scores of grade III with grade II tumors. Combining the rCBV and ITSS resulted in significant improvement in the discrimination of grade III from grade IV tumors.

Conclusion

The combination of rCBV values derived from T1-perfusion MRI and SWI derived ITSS scores improves the diagnostic accuracy for discrimination of grade III from grade IV gliomas.