Whole-brain voxel-based morphometry of white matter in mild cognitive impairment

Purpose

The purpose of this study was to analyze whole-brain white matter changes in mild cognitive impairment (MCI).

Materials and methods

We studied 14 patients with MCI and 14 age- and sex-matched healthy control subjects using voxel-based morphometry (VBM) on T1-weighted 3D datasets. The data were collected on a 3T MR system and analyzed by SPM2 to generate white matter volume maps.

Results

Voxel-based morphometry revealed diffusively reduced white matter in MCI prominently including the bilateral temporal gyrus, the right anterior cingulate, the bilateral superior and medial frontal gyrus and right parietal angular gyrus. White matter reduction was more prominent in anterior regions than that in posterior regions.

Conclusion

Whole-brain white matter reduction in MCI patients detected with VBM has special distribution which is in line with the white matter pathology of MCI.     

High-resolution diffusion tensor imaging of prostate cancer using a reduced FOV technique

Objective

Diffusion tensor imaging (DTI) offers the promise of improved tumor localization in prostate cancer but the technique suffers from susceptibility-induced artifacts that limit the achievable resolution. The present work employs a reduced field-of-view technique that enables high-resolution DTI of the prostate at 3 T. Feasibility of the approach is demonstrated in a clinical study including 26 patients and 14 controls.

Materials and methods

Reduced field-of-view acquisition was established by non-coplanar application of the excitation and the refocusing pulse in conjunction with outer volume suppression. Accuracy for cancer detection of apparent diffusion coefficient (ADC) mapping and T₂-weighted imaging was calculated and compared with reference to the findings of trans-rectal ultrasound-guided octant biopsy. Mean ADCs and fractional anisotropy (FA) values in the patients with positive and negative biopsies were compared to each other and to the controls.

Results

Fine anatomical details were successfully depicted on the ADC maps with sub-millimeter resolution. Accuracy for prostate cancer detection was 73.5% for ADC maps and 71% for T₂-weighted images, respectively. Cohen's kappa (κ = 0.48) indicated moderate agreement of the two methods. The mean ADCs were significantly lower, the FA values higher, in the patients with positive biopsy than in the patients with negative biopsy and the controls. Monte Carlo simulations showed that the FA values, but not the ADCs, were slightly overestimated. Bootstrap analysis revealed that the ADC, but not the FA value, is a highly repeatable marker.

Conclusion

In conclusion, the present work introduces a new approach for high-resolution DTI of the prostate enabling a more accurate detection of focal tumors especially useful in screening populations or as a potential navigator for image-guided biopsy.     

Assessment of nonstenotic coronary lesions by 64-slice multidetector computed tomography in comparison to intravascular ultrasound: Evaluation of nonculprit coronary lesions

Background

Multidetector computed tomography (MDCT) has recently emerged as a potential noninvasive alternative for high-resolution imaging of coronary arteries.

Objective

In this study, we evaluated 64-slice MDCT for detection, quantification, and characterization of atherosclerotic plaque burden in nonculprit lesions.

Methods

Data from 11 patients who underwent both MDCT and intravascular ultrasound (IVUS) for suspected coronary artery disease were collected, and a total of 17 coronary segments and 122 cross-sectional slices were analyzed by MDCT and IVUS. Coronary segments on MDCT were coregistered to IVUS, and each obtained slice was scored by 2 blinded observers for presence and type of plaque. Quantitative measurements included cross-sectional vessel area, lumen area, wall area, plaque volume, and plaque burden. Mean and standard deviation of Hounsfield units (HUs) were recorded for plaque when present.

Results

Overall sensitivity for plaque detection was 95.0%, and specificity, positive predictive value, negative predictive value were 88.7%, 89.1%, and 94.8%, respectively. Spearman's correlation coefficients were 0.85, 0.75, 0.70, 0.89, and 0.54 for cross-sectional vessel area, lumen area, wall area, plaque volume, and plaque burden, respectively. The interobserver variability for plaque burden and plaque volume measurements between readers on 64-MDCT was high at 32.7% and 30.4%, respectively. Combined noncalcified plaque had a mean MDCT density significantly different from that of calcified plaque. Soft and fibrous plaques were not able to be distinguished based on their HU values.

Conclusion

Sixty-four-slice MDCT had good correlation with IVUS but with high interobserver variability. Plaque characterization remains a challenge with present MDCT technology.     

7 Tesla quantitative hip MRI: T1, T2 and T2* mapping of hip cartilage in healthy volunteers

Objectives

To evaluate the technical feasibility and applicability of quantitative MR techniques (delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), T2 mapping, T2* mapping) at 7 T MRI for assessing hip cartilage.

Methods

Hips of 11 healthy volunteers were examined at 7 T MRI with an 8-channel radiofrequency transmit/receive body coil using multi-echo sequences for T2 and T2* mapping and a dual flip angle gradient-echo sequence before (T1₀) and after intravenous contrast agent administration (T1_Gd; 0.2 mmol/kg Gd-DTPA^2? followed by 0.5 h of walking and 0.5 h of rest) for dGEMRIC. Relaxation times of cartilage were measured manually in 10 regions of interest. Pearson’s correlations between R1_delta?=?1/T1_Gd???1/T1₀ and T1_Gd and between T2 and T2* were calculated. Image quality and the delineation of acetabular and femoral cartilage in the relaxation time maps were evaluated using discrete rating scales.

Results

High correlations were found between R1_delta and T1_Gd and between T2 and T2* relaxation times (all p?<?0.01). All techniques delivered diagnostic image quality, with best delineation of femoral and acetabular cartilage in the T2* maps (mean 3.2 out of a maximum of 4 points).

Conclusions

T1, T2 and T2* mapping of hip cartilage with diagnostic image quality is feasible at 7 T. To perform dGEMRIC at 7 T, pre-contrast T1 mapping can be omitted.

Key Points

? dGEMRIC of hip cartilage with diagnostic image quality is feasible at 7 T. ? To perform dGEMRIC at 7 T, pre-contrast T1 mapping can be omitted. ? T2(*) mapping of hip cartilage with diagnostic image quality is feasible at 7 T. ? T2 and T2* relaxation times of cartilage were highly correlated at 7 T. ? Best delineation of femoral and acetabular cartilage was found in T2* maps.

     

Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), after slipped capital femoral epiphysis

Objective

The aim of this study was to assess the glycosaminoglycan (GAG) content in hip joint cartilage in mature hips with a history of slipped capital femoral epiphysis (SCFE) using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC).

Methods

28 young-adult subjects (32 hips) with a mean age of 23.8 ± 4.0 years (range: 18.1-30.5 years) who were treated for mild or moderate SCFE in adolescence were included into the study. Hip function and clinical symptoms were evaluated with the Harris hip score (HHS) system at the time of MRI. Plain radiographic evaluation included Tonnis grading, measurement of the minimal joint space width (JSW) and alpha-angle measurement. The alpha-angle values were used to classify three sub-groups: group 1 = subjects with normal femoral head-neck offset (alpha-angle <50°), group 2 = subjects with mild offset decrease (alpha-angle 50°-60°), and group 3 = subjects with severe offset decrease (alpha-angle >60°).

Results

There was statistically significant difference noted for the T1_Gd values, lateral and central, between group 1 and group 3 (p-values = 0.038 and 0.041). The T1_Gd values measured within the lateral portion were slightly lower compared with the T1_Gd values measured within the central portion that was at a statistically significance level (p-value <0.001). HHS, Tonnis grades and JSW revealed no statistically significant difference.

Conclusion

By using dGEMRIC in the mid-term follow-up of SCFE we were able to reveal degenerative changes even in the absence of joint space narrowing that seem to be related to the degree of offset pathology. The dGEMRIC technique may be a potential diagnostic modality in the follow-up evaluation of SCFE.     

MR evaluation of PDMS injections in head and neck tissues: A pilot study

Objectives

To describe the magnetic resonance (MR) appearance of polydimethylsiloxane (PDMS) injections in the head and neck region.

Study design

Retrospective review of MR images from a case series.

Methods

MR images of 10 patients, who underwent PDMS injections at our department, were reviewed. Data from imaging were collected and analyzed.

Results

After injection, PDMS can be identified in MR images, particularly in T2-weighted images in the early stages. Its MR characteristics are similar to silicone in other regions, but with time, its appearance can change.

Conclusions

The integration of PDMS with tissues may also be reflected in changes in MR appearance, as a result of an increased amount of fibrous tissue in the region injected. Radiologists and ENT specialists may benefit from knowledge of the MR characteristics and variability in appearance of PDMS in human tissues for improving image interpretation.     

Accelerated time-resolved three-dimensional MR velocity mapping of blood flow patterns in the aorta using SENSE and k-t BLAST

Purpose

To assess the feasibility and potential limitations of the acceleration techniques SENSE and k-t BLAST for time-resolved three-dimensional (3D) velocity mapping of aortic blood flow. Furthermore, to quantify differences in peak velocity versus heart phase curves.

Materials and methods

Time-resolved 3D blood flow patterns were investigated in eleven volunteers and two patients suffering from aortic diseases with accelerated PC-MR sequences either in combination with SENSE (R = 2) or k-t BLAST (6-fold). Both sequences showed similar data acquisition times and hence acceleration efficiency. Flow-field streamlines were calculated and visualized using the GTFlow software tool in order to reconstruct 3D aortic blood flow patterns. Differences between the peak velocities from single-slice PC-MRI experiments using SENSE 2 and k-t BLAST 6 were calculated for the whole cardiac cycle and averaged for all volunteers.

Results

Reconstruction of 3D flow patterns in volunteers revealed attenuations in blood flow dynamics for k-t BLAST 6 compared to SENSE 2 in terms of 3D streamlines showing fewer and less distinct vortices and reduction in peak velocity, which is caused by temporal blurring. Solely by time-resolved 3D MR velocity mapping in combination with SENSE detected pathologic blood flow patterns in patients with aortic diseases. For volunteers, we found a broadening and flattering of the peak velocity versus heart phase diagram between the two acceleration techniques, which is an evidence for the temporal blurring of the k-t BLAST approach.

Conclusion

We demonstrated the feasibility of SENSE and detected potential limitations of k-t BLAST when used for time-resolved 3D velocity mapping. The effects of higher k-t BLAST acceleration factors have to be considered for application in 3D velocity mapping.     

A head phantom study for intraocular dose evaluation of 64-slice multidetector CT examination in patients with suspected cranial trauma

Purpose

In cases of suspected cranial trauma, cranial CT examinations should be performed to rule out pathology. There are some methods available for reducing intraocular doses; however, it is difficult for the operators to conduct the necessary measurements because of restrictions in time and patient mobility, especially in high-energy trauma cases. Therefore, we performed a head phantom study for intraocular dose evaluation of 64-slice multidetector CT examination in patients with suspected cranial trauma.

Materials and methods

Assuming that the orbitomeatal (OM) line and bed were vertical, a head phantom was tilted from 10 degrees caudally to 25 degrees cranially at 5-degree intervals. At each tilted position, the phantom was examined using a 64-section multidetector CT device using three acquisition protocols. Intraocular doses during each examination were measured using small dosimeters.

Results

Assuming that the OM line and bed were vertical, intraocular doses varied between 52 and 140%, 17-138%, and 90-142% during helical, non-helical, and helical CT angiographic examinations, respectively. Intraocular doses increased when the phantom was tilted cranially.

Conclusion

If possible, the best way to reduce the intraocular dose is by angling the gantry cranially, tilting the head of each patient caudally and adopting a non-helical acquisition method. During procedure, the acquisition angle should be angled cranially more than 0 degrees based on the OM line. The estimation of intraocular dose using the acquisition angle and displayed volumetric CT dose index might be useful to evaluate the deterministic effect risks and to inform patients about the associated risks.     

Perfusion maps of the whole liver based on high temporal and spatial resolution contrast-enhanced MRI (4D THRIVE): Feasibility and initial results in focal liver lesions

Purpose

To prospectively evaluate a new imaging sequence (4D THRIVE) for whole liver perfusion in high temporal and spatial resolution. Feasibility of parametric mapping and its potential for characterizing focal liver lesions (FLLs) are investigated.

Materials and methods

Fifteen patients suspected for colorectal liver metastases (LMs) were included. Parametric maps were evaluated qualitatively (ring-enhancement and lesion heterogeneity) and compared to three-phased contrast-enhanced MRI. Quantitative analysis was based on average perfusion values of entire FLLs. Reference standard comprised surgery with histopathology or follow-up imaging. Fisher's exact test was used for qualitative and Kruskal-Wallis test for quantitative analysis.

Results

In total 29 LMs, 17 hemangiomas and 4 focal nodular hyperplasias were evaluated. FLLs could be differentiated by qualitative assessment of parametric maps respectively three-phased contrast-enhanced MRI (Fisher's p < 0.001 for comparisons between LMs and hemangiomas and LMs and FNHs for both ring-enhancement and lesion heterogeneity) rather than by quantitative analysis of parametric maps (Chi-square for Kep = 0.33 (p = 0.847) and Chi-square for Kel = 1.35 (p = 0.509)).

Conclusion

This preliminary study shows potential of 4D THRIVE for whole liver imaging enabling calculation of parametric maps. Qualitative rather than quantitative analysis was accurate for differentiating malignant and benign FLLs.     

Comparison of lateral abdominal muscle thickness between weightlifters and matched controls

Objective

To compare lateral abdominal muscle thickness between weightlifters and matched controls.

Design

A case control study design.

Setting

University laboratory.

Subjects

16 female Thai national weightlifters and 16 matched controls participated in this study.

Main outcome measures

Ultrasound imaging with a 12-MHz linear array was used to measure the resting thickness of transversus abdominis (TrA), internal oblique (IO) and total thickness (Total) of lateral abdominal muscle (LAM) on the right side of abdominal wall. The absolute muscle thickness and the relative contribution of each muscle to the total thickness were determined.

Results

Weightlifters had significantly thicker absolute TrA and IO muscles than matched controls (p < 0.01). Further, the relative thickness of the IO was significantly greater in weightlifters than matched controls (p < 0.05).

Conclusions

The findings of this study suggest that routine Olympic style weight training among female weightlifters appears to result in preferential hypertrophy or adaptation of the IO muscle.     

Preoperative detection of hepatic metastases: Comparison of diffusion-weighted, T2-weighted fast spin echo and gadolinium-enhanced MR imaging using surgical and histopathologic findings as standard of reference

Purpose

The purpose of this study was to retrospectively compare the respective sensitivities of diffusion-weighted (DW), T2-weighted fast spin-echo (T2WFSE) and gadolinium chelate-enhanced MR imaging in the preoperative detection of hepatic metastases using intraoperative ultrasonographic and histopathologic findings as the standard of reference.

Materials and methods

Twenty-seven patients with 64 surgically and histopathologically proven hepatic metastases had MR imaging of the liver, including DW, T2WFSE and dynamic gadolinium chelate-enhanced MR imaging. Images from each MR sequence were separately analyzed by two readers with disagreements resolved by consensus readings. The findings on MR images were compared with intraoperative ultrasonographic and histopathologic findings on a lesion-by-lesion basis to determine the sensitivity of each MR sequence. Statistical review of the lesion-by-lesion analysis was performed with the McNemar test.

Results

DW, T2WFSE and gadolinium chelate-enhanced MR imaging allowed the depiction of 54/64 (84.4%; 95% CI: 73.1-92.2%), 44/64 (68.8%; 95% CI: 55.9-79.8%), and 51/64 (79.7%; 95% CI: 67.8-88.7%) hepatic metastases respectively. DW MR images allowed depiction of significantly more hepatic metastases than did T2WFSE and was equivalent to gadolinium chelate-enhanced MR imaging (P = .002 and P = .375, respectively).

Conclusion

DW MR imaging is superior to T2WFSE imaging and equivalent to gadolinium chelate-enhanced MR imaging for the preoperative detection of hepatic metastases. Further studies however are needed to determine at what extent DW MR imaging can be used as an alternative to gadolinium chelate-enhanced MR imaging for the preoperative depiction of hepatic metastases.     

Delayed gadolinium‐enhanced MRI of cartilage in the ankle at 3 T: Feasibility and preliminary results after matrix‐associated autologous chondrocyte implantation

Purpose:

To demonstrate the feasibility of delayed gadolinium‐enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) in the ankle at 3 T and to obtain preliminary data on matrix associated autologous chondrocyte (MACI) repair tissue.

Materials and Methods:

A 3D dual flip angle sequence was used with an eight‐channel multipurpose coil at 3 T to obtain T1 maps both pre‐ and postintravenous contrast agent (Magnevist, 0.2 mM/kg). Postcontrast T1 over time was evaluated in three volunteers; a modified dGEMRIC protocol was then used to assess 10 cases after MACI in the ankle.

Results:

Forty‐five minutes were found sufficient for maximum T1 decrease. MACI cases had a precontrast mean T1 of 1050 ± 148.4 msec in reference cartilage (RC) and 1080 ± 165.6 msec in repair tissue (RT). Postcontrast T1 decreased to 590 ± 134.0 msec in RC and 554 ± 133.0 msec in RT. There was no significant difference between the delta relaxation rates in RT (9.44 × 10^?4 s^?1) and RC (8.04 × 10^?4 s^?1, P = 0.487). The mean relative delta relaxation rate was 1.34 ± 0.83.

Conclusion:

It is feasible to assess the thin cartilage layers of the ankle with dGEMRIC at 3 T; MACI can yield RT with properties similar to articular cartilage. J. Magn. Reson. Imaging 2010;31:732–739. © 2010 Wiley‐Liss, Inc.

     

Superior cerebellar artery infarction in endovascular treatment for tentorial dural arteriovenous fistulas

Background

Superior cerebellar artery (SCA) syndrome shows ipsilateral cerebellar ataxia and Horner's syndrome, contralateral superficial sensory disturbance, as well as nystagmus toward the impaired side, vertigo, and nausea. Occasionally, unilateral lesions may produce bilateral hypogeusia and contralateral hypoacusia.

Objective

To report 2 patients with unilateral lower midbrain ischemic lesions of the inferior colliculus level caused by transarterial embolization for tentorial dural arteriovenous fistulas (TDAVFs).

Methods

Hospital records for 21 patients with TDAVFs mainly treated by endovascular techniques between 2005 and 2008 were reviewed. Two patients with MRI evidence of unilateral SCA territory infarction were investigated.

Results

Of 21 patients, 2 treated transarterially with Onyx-18 (a nonahesive liquid embolic agent) developed infarctions in the territory of SCA. One patient had lateral SCA infarction characterized by ipsilateral gait ataxia, contralateral hemihypoesthesia, with additional ipsilateral ocular motor palsy and bilateral gustatory loss. And the other patient had medial SCA infarction characterized by ipsilateral ataxia contralateral hemihypoesthesia with additional contralateral hypoacusia.

Conclusion

SCA infarction can be caused by transarterial injection of Onyx-18 via SCA or the posterior cerebral artery (PCA) for TDAVFs and additionally presented with gustatory loss and deafness, which is generally not a feature of the SCA syndrome.     

Detection of biliary stenoses in patients after liver transplantation: Is there a different diagnostic accuracy of MRCP depending on the type of biliary anastomosis?

Purpose

Two different forms of biliary anastomosis can be created in patients undergoing liver transplantation: (a) bilio-digestive anastomoses or (b) choledocho-choledochostomy. Aim of this study was to assess the accuracy of MR cholangiopancreatography (MRCP) for the depiction of biliary stenoses in liver transplant patients depending on the type of biliary anastomosis.

Method and materials

24 liver transplant patients with clinical suspicion of biliary stenosis were studied (each 12 with bilio-digestive anastomosis/choledocho-choledochostomy). MRCP was performed on a 1.5T scanner (Magnetom Avanto, Siemens) including 2D single shot RARE, 2D T2w HASTE, TrueFISP and 3D high-resolution navigator corrected sequences. Presence of (a) anastomotic stenoses (AST) and (b) NAS (non-anastomotic strictures) were assessed. Percutaneous transhepatic cholangiography (PTC) or endoscopic retrograde cholangiopancreatography (ERCP) were performed within 48 h after MRCP and served as the standard of reference.

Results

In patients with bilio-digestive anastomoses sensitivities of MRCP for the detection of AST and NAS amounted to 50% and 67%, respectively with specificity values of 83% and 50%. In patients with choledocho-chledochostomy sensitivities (AST: 100%, NAS: 100%) and specificities (AST: 100%, NAS: 88%) were significantly higher.

Conclusion

Biliary strictures after liver transplantation can be accurately detected by MRCP in patients after choledocho-chledochostomy. However, the diagnostic value of MRCP is lower if liver transplantation was performed in combination with a bilio-digestive anastomosis. This may be due to the less exact depiction of the anastomosis in the bowel wall. Thus, it is crucial to know the type of biliary anastomosis before choosing a diagnostic procedure.     

Contrast enhanced IR-SSFP examination compared with T1-weighted turbo spin-echo imaging of cardiac tumors and tumorlike lesions

Purpose

To show that the use of an early and delayed contrast enhanced multislice inversion recovery steady state free precession (SS-IR-SSFP) is a valuable substitute for conventional post-contrast fat saturated turbo spin-echo (TSE) T1-weighted images in the assessment of cardiac tumors.

Materials and methods

34 consecutive patients referred for MRI in order to assess cardiac tumors were examined. Shortly after administration of gadopenetate dimeglumine (Gd-DTPA) images were obtained using a SS-IR-SSFP sequence. The inversion time (TI) was set at 350 ms to achieve a good demarcation of intracavitary tumor spread. Hereafter 9 slices of a T1w TSE sequence were obtained. Finally a SS-IR-SSFP sequence with an optimized TI to null normal myocardium was employed. Quantitative comparisons were performed by calculating contrast to noise ratios of tumor/myocardium (CNR_tumor/myo) and CNR of tumor/left ventricular cavity (CNR_tumor/LVC). Image quality was assessed regarding overall image quality, artifacts and tumor conspicuity.

Results

Neither calculation of CNR_tumor/LVC when comparing the early IR-SSFP and T1w TSE, nor calculation of CNR_tumor/myo when comparing the late IR-SSFP and T1w TSE sequence resulted in statistically significant differences. However, qualitative assessments revealed significant superior results for the early and the late IR-SSFP images compared to the T1-weighted TSE images (p < 0.001).

Conclusions

Image quality and tumor conspicuity were superior and image degradation by artifacts was less on IR-SSFP images compared to TSE images without loss of CNR. Thus the use of IR-SSFP sequences is an attractive alternative imaging method compared to post-contrast T1w TSE imaging in the assessment of cardiac tumors.     

Small vestibular schwannomas can cause gait instability

Purpose

To confirm whether detailed gait analysis can detect gait instability in patients with small vestibular schwannoma (VS) with an apparently normal gait.

Methods

Twenty-two patients (7 males, 15 females; 40-64 years old) with small VS and nine healthy age- and weight-matched controls were enrolled. Small VS was defined as the longest diameter less than 20 mm from the porus acusticus internus on MRI with no brainstem compression. Each subject was asked to walk straight for a distance of 8 m with tactile sensors attached to both feet, and repeat two trials with eyes open and closed. Gait variables of stance, swing, double support, stability, and average length of the trajectories of the center of force (TCOF) during stance were recorded and analyzed.

Results

No significant differences in the stability of the TCOF were found during gaits with eyes open and closed between the two groups. No obvious changes in gait variables were recognized with eyes open between the two groups. However, under gait with eyes closed, the values of the coefficient of variation (CV) of the gait phase were significantly greater in stance and swing in the VS group than in the normal group. In addition, patients with canal paresis (CP) showed greater CV values in gait phase related parameters than those who without CP during gait with eyes closed.

Conclusions

Patients with small VS may have an apparently normal gait, but their vestibular deficit could be detected by proper use of gait analysis, especially with visual deprivation.     

Lung perfusion CT: The differentiation of cavitary mass

Purpose

To assess the findings of perfusion maps and to evaluate the usefulness of perfusion computed tomography (CT) in the differentiation of cavitary mass.

Materials and methods

Fifty-three patients with cavitary lung masses were analyzed. Dynamic chest CT was performed after contrast injection. The volume map, washout map, peak map, and time-to-peak (TTP) map were reformatted using Interactive Data Language (IDL). The perfusion patterns were classified into three scoring groups, and these scorings were repeated after 2-week intervals. Diagnostic confidence levels were assigned by consensus. The kappa statistics was used to determine intraobserver agreement, and Fisher's exact test was used to analyze statistical differences in perfusion scores. Receiver operating characteristic (ROC) analysis was performed to evaluate the usefulness of the perfusion maps.

Results

Perfusion maps were reformatted pixel-by-pixel from the time-to-density curve analyses. Pyogenic cavities showed weak washout and slow TTP (69.6%). Conversely, malignant cavities showed strong washout (73.3%). Tuberculous cavities showed low perfusions in the volume and peak maps (66.7%). Intraobserver agreement was excellent. The performance of the combination of CT and perfusion maps was better than that of CT alone.

Conclusion

Lung perfusion CT could be a promising and feasible method for differentiation of cavitary mass.     

Cerebral diffusion tensor imaging in tuberous sclerosis

Purpose

The purpose of this study was to investigate the features of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in cortical tubers and white-matter lesions in patients with tuberous sclerosis (TS) using diffusion tensor imaging (DTI).

Materials and methods

Conventional magnetic resonance imaging (MRI) and DTI were performed in 14 patients with clinically established TS. Based on these DT images, ADC and FA maps were generated. The ADC values in 32 cortical tubers, and the ADC and FA values in 18 white-matter lesions were measured and compared with those of the corresponding contralateral regions.

Results

Compared with the corresponding contralateral regions, cortical tubers of TS patients had significantly higher ADC values (P < 0.001); white-matter lesions had significantly higher ADC values (P < 0.001) and significantly lower FA values (P < 0.001).

Conclusion

DTI is a useful tool for demonstrating changes in cortical tubers and white-matter lesions resulting from TS.     

Diffusion tensor magnetic resonance imaging of glial brain tumors

Aim

To evaluate the author's experience with the use of diffusion tensor magnetic resonance imaging (DTI) on patients with glial tumors.

Methods

A retrospective evaluation of a group of 24 patients with glial tumors was performed. There were eight patients with Grade II, eight patients with Grade III and eight patients with Grade IV tumors with a histologically proven diagnosis. All the patients underwent routine imaging including T2 weighted images, multidirectional diffusion weighted imaging (measured in 60 non-collinear directions) and T1 weighted non-enhanced and contrast enhanced images. The imaging sequence and evaluation software were produced by Massachusetts General Hospital Corporation (Boston, MA, USA). Fractional anisotropy (FA) maps were calculated in all patients. The white matter FA changes were assessed within the tumorous tissue, on the tumorous borderline and in the normally appearing white matter adjacent to the tumor. A three-dimensional model of the white matter tract was created to demonstrate the space relationship of the tumor and the capsula interna or corpus callosum in each case using the following fiber tracing parameters: FA step 0.25 and a tensor declination angle of 45 gr. An additional assessment of the tumorous tissue enhancement was performed.

Results

A uniform homogenous structure with sharp demargination of the Grade II tumors and the wide rim of the intermedial FA in all Grade III tumors respectively, were found during the evaluation of the FA maps. In Grade IV tumors a variable demargination was noted on the FA maps. The sensitivity and specificity for the discrimination of low- and high-grade glial tumors using FA maps was revealed to be 81% and 87% respectively. If the evaluation of the contrast enhancement was combined with the evaluation of the FA maps, both sensitivity and specificity were 100%.

Conclusion

Although the evaluation of the fractional anisotropy maps is not sufficient for glioma grading, the combination of the contrast enhancement pattern and fractional anisotropy maps evaluation improves the possibility of distinguishing low- and high-grade glial tumors. Three-dimensional models of the white matter fibers in the corpus callosum and the internal capsule may be used in the presurgical planning.     

MR spectroscopy findings in tuberculous spondylitis; comparison with Modic type-I end-plate changes and metastatic vertebral disease

Purpose

To define single-voxel proton magnetic resonance spectroscopy (MRS) findings of vertebral tuberculous spondylitis (TBS), Modic type-I end-plate changes (MTEC) and metastatic vertebral disease (MVD).

Materials and methods

Fifteen patients with TBS, 15 with MTEC and 15 with MVD were included. MRS from the diseased vertebral body as well as normal vertebral body was examined. Water and lipid peak were measured, water-to-lipid ratio (WLR) and for each patient lesion water index (LWI, the ratio of WLRs from diseased to normal vertebrae) were calculated.

Results

The mean WLR of normal and pathologic vertebra was 0.91 and 7.13 in TBS group, 0.84 and 3.49 in MTEC group and 0.65 and 3.17 in MVD group, respectively. The mean LWI was 10.68 in TBS, 6.04 in MTEC and 6.42 MVD groups. Statistical significance was not achieved between the WLR and LWI of the TBS, MTEC nor MVD group (p > 0.05).

Conclusion

The mean values of WLR and LWI in the TBS group are relatively higher than MTEC and MVD groups, with the difference being statistically insignificant.