Improved diffusion-weighted imaging of the prostate: Comparison of readout-segmented and zoomed single-shot imaging.

OBJECTIVES: Diffusion weighted imaging (DWI) is the most important sequence for detection and grading prostate cancer (PCa), but it is considerably prone to artifacts. New approaches like zoomed single-shot imaging (z-EPI) with advanced image processing or multi-shot readout segmentation (rs-EPI) try to improve DWI quality. This study evaluates objective and subjective image quality (IQ) of rs-EPI and z-EPI with and without advanced processing. MATERIALS AND METHODS: Fifty-six consecutive patients (67 ± 8 years; median PSA 8.3 ng/ml) with mp-MRI performed at 3 Tesla between February and October 2019 and subsequently verified PCa by targeted plus systematic MRI/US-fusion biopsy were included in this retrospective single center cohort study. Rs-EPI and z-EPI were prospectively acquired in every patient. Signal intensities (SI) of PCa and benign tissue in ADC, b1000, and calculated high b-value images were analyzed. Endpoints were signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), PCa contrast intensity (CI), and subjective IQ on a 5-point scale evaluated by three blinded readers. Wilcoxon signed rank test, Friedman test and Cohen's kappa coefficient was calculated. RESULTS: SNR, CNR, and PCa CI of z-EPI with and without advanced processing was superior to rs-EPI (p < 0.01), whereas no significant differences were observed between z-EPI with and without advanced processing. Subjective IQ was significantly higher for z-EPI with advanced processing compared rs-EPI for ADC, b1000, and calculated high b-values (p < 0.01). Compared to z-EPI without advanced processing, z-EPI with advanced processing was superior for ADC and calculated high b-values (p < 0.01), but no significant differences were shown for b1000 images. CONCLUSIONS: Z-EPI with and without advanced processing was superior to rs-EPI regarding objective imaging parameters and z-EPI with advanced processing was superior to rs-EPI regarding subjective imaging parameters for the detection of PCa.

Feasibility of renal perfusion quantification by Fourier decomposition MRI.

PURPOSE: To evaluate the feasibility of perfusion measurements in the human kidney by Fourier decomposition MRI (FD-MRI). METHODS: Renal perfusion measurements by FD-MRI and arterial spin labeling (ASL) were performed using a 1.5 T whole-body MR-scanner (Magnetom Avanto, Siemens Healthineers AG, Germany) in 15 healthy volunteers (mean age 33.0 ± 13.6 years). Five healthy volunteers were measured twice to evaluate the reproducibility. Besides, five patients with renal artery stenosis (RAS) (mean age 58.4 ± 16.2 years) were included in the study to evaluate potential clinical use of the FD-MRI for evaluating renal perfusion. For renal FD-MRI, coronal 2D-TrueFisp sequence (1 section; section thickness: 10 mm; FOV: 400 × 400 mm 2; TR/TE: 2.06/0.89 ms; 250 images; 0,36 s/image), for renal ASL, coronal FAIR-TrueFisp sequence (1 section; section thickness: 10 mm; FOV: 400 × 400 mm2; TR/TE 4.0/2.0 ms, TI 1200 ms, 30 averages; 8,32 s/average) were acquired without any triggering. Perfusion parameter maps of the kidneys were calculated for both methods. After manual segmentation, ROI-based analysis (whole kidney, cortex and medulla, respectively) was performed and the results were subsequently compared using the Student t-test. RESULTS: The acquisition times were 1.30 min and 4.16 min, for renal FD-MRI and ASL, respectively. No significant difference in global renal perfusion (RBF) between both methods was detected (mean RBF in the right kidney: 308.4 ± 31.5 mL/100 mL/min for FD-MRI; 315.2 ± 41.1 for ASL; in the left kidney: 315.6 ± 32.8 mL/100 mL/min for FD-MRI; 310.2 ± 39.1 mL/100 mL/min for ASL, respectively). The results indicated good reproducibility of both considered methods. However, cortico-medullar differentiation was not possible by FD-MRI, probably due to lower SNR compared to ASL. Significant difference in the side-separated RBF were measured by FD-MRI as well as by ASL (p < 0.05) in patients with RAS. CONCLUSIONS: FD-MRI is a novel, rapid approach for contrast-free perfusion quantification in the human kidney. Main advantage of this new method compared to ASL perfusion is the significant shorter acquisition time and lower dependency on patient's compliance. However, lower SNR of FD-MRI needs further improvement to make FD-MRI a competitive alternative to ASL.

Arterial spin labelling as a gadolinium-free alternative in the detection of prostate cancer.

PURPOSE: To determine the capability of Gadolinium-free arterial spin labelling (ASL) sequences as novel, contrast-free, non-invasive alternative perfusion imaging method to differentiate prostate cancer (PCA) from benign prostate tissue compared to conventional DCE MRI. METHODS: Thirty men with histologically confirmed PCA were included in this prospectively enrolled single center cohort study. All patients received multiparametric MRI (T2, DWI, DCE) at 3 T with additional ASL of the PCA lesion. Primary endpoint was differentiability of PCA versus benign prostate tissue by signal intensities (SI) and contrast ratios (CR) in ASL in comparison to DCE. For DCE also Signal-Enhancement-Ratio (SER) of native and early contrast enhancement SI was assessed. Secondary objectives were differences regarding PCA localisation in peripheral (PZ) or transition zone (TZ) and PCA detection. RESULTS: In both, ASL and DCE, average SI of PCA differed significantly from SI in benign tissue in the TZ and PZ (p < 0,01, respectively). ASL had significantly higher CR discerning PCA and benign tissue in PZ and TZ (PZ = 5.19; TZ = 6.45) compared to DCE SI (PZ = 1.61; TZ = 1.43) and DCE SER (PZ = 1.59; TZ = 1.43) (p < 0.01, respectively). In subjective evaluation, PCA could be detected in ASL in 28 patients, compared to 29 in DCE. CONCLUSION: ASL had significantly higher CR differentiating PCA from benign tissue in PZ and TZ compared to DCE. Visual detection of PCA does not differ significantly between the two sequences. As perfusion gadolinium-based contrast media is seen more critical in the last few years, ASL seems to be a promising alternative to DCE in PCA detection.

Influence of arterial input function (AIF) on quantitative prostate dynamic contrast-enhanced (DCE) MRI and zonal prostate anatomy.

PURPOSE: Reproducibility of quantitative perfusion analysis of DCE requires a standardized AIF acquisition. However, there are many different approaches for AIF assessment so that the absolute values of perfusion parameters may vary depending on the used method. This study analyzes the influence of the method of AIF determination on quantitative DCE-MRI. METHODS: In this retrospective, single-center, cohort study three different methods of AIF determination in 50 consecutive patients with multiparametric MRI of the prostate were conducted. As a reference, AIF was selected manually by defining a region of interest in an artery manually (AIFm). The second method (AIFa), based on an automated algorithm and the third, population-derived AIFp where then compared. Primary endpoint were differences in the performance of the perfusion parameters Ktrans, ve and kep regarding the AIF acquisition methods, secondary endpoints consisted of the evaluation of differences in the peripheral and transition zone of the prostate (PZ, TZ). RESULTS: In all three methods, Ktrans, ve, and kep were significantly higher in PZ than in TZ with Ktrans showing least overlapping. There were no significant differences for Ktrans determined with AIFm and AIFa (0.3 ±â€¯0.2 min-1 for PZ for both and 0.5 ±â€¯0.3 min-1 for TZ in AIFm and 0.4 ±â€¯0.3 min-1 in AIFa), while there were great differences between AIFa and AIFp and AIFm and AIFp (0.1 ±â€¯0.03 min-1 for TZ and PZ in AIFp). Spearman test demonstrated good correlation of values for Ktrans and kep in all 3 methods (ρ ≥ 0.76). AIFa showed a success rate of 98% in finding the artery. CONCLUSION: AIFa is a recommendable user-independent automatical method to determine quantitative perfusion parameters allowing an objective measurement and saving interactive time for the radiologist. AIFp may be applied as second alternative method.

Magnetic resonance imaging of the prostate at 1.5 versus 3.0T: A prospective comparison study of image quality.

OBJECTIVES: This study prospectively evaluates objective image quality (IQ), subjective IQ, and PI-RADS scoring of prostate MRI at 3.0T (3T) and 1.5T (1.5T) within the same patients. METHODS: Sixty-three consecutive patients (64±9years) were prospectively included in this non-inferiority trial, powered at 80% to demonstrate a ≤10% difference in signal-to-noise (SNR) and contrast-to-noise ratio (CNR) of T2-weighted and diffusion-weighted imaging (T2WI, DWI) at 1.5T compared to 3T. Secondary endpoints were analysis of subjective IQ and PI-RADS v2 scoring. RESULTS: All patients received multi-parametric prostate MRI on a 3T (T2WI, DWI, DCE) and bi-parametric MRI (T2WI, DWI) on a 1.5T scanner using body coils, respectively. SNR and CNR of T2WI were similar at 1.5T and 3T (p=0.7-1), but of DWI significantly lower at 1.5T (p<0.01). Subjective IQ was significantly better at 3T for both, T2WI and DWI (p<0.01). PI-RADS scores were comparable for both field strengths (p=0.05-1). Inter-reader agreement was excellent for subjective IQ assessment and PI-RADS scoring (k=0.9-1). CONCLUSION: Prostate MRI at 1.5T can reveal comparable objective image quality in T2WI, but is inferior to 3T in DWI and subjective IQ. However, similar PI-RADS scoring and thus diagnostic performance seems feasible independent of the field strength even without an endorectal coil.

Facet tropism and facet joint orientation: risk factors for the development of early biochemical alterations of lumbar intervertebral discs.

OBJECTIVE: To assess the glycosaminoglycan (GAG) content of lumbar intervertebral discs (IVD) in healthy volunteers with facet tropism (FT) and sagittal facet joint (FJ) orientation using glycosaminoglycan chemical exchange saturation transfer imaging (gagCEST). METHOD: Seventy-five lumbar IVDs of twenty-five young, healthy volunteers without any history of lumbar spine pathologies (13 female; 12 male; mean age: 28.0 ± 4.4 years; range: 21-35 years) were examined with a 3T MRI scanner. Orientation of FT and FJ were assessed for L3/4, L4/5 and L5/S1 using standard T2 weighted images. Biochemical gagCEST imaging was used to determine the GAG content of each nucleus pulposus (NP) and annulus fibrosus (AF). RESULTS: Significantly higher gagCEST values of NP were found in volunteers without FT and normal FJ orientation compared to volunteers with FT and sagittal FJ orientation >45° (P < 0.0001). GagCEST values were significantly higher in volunteers without FT compared to volunteers with moderate or severe FT (moderate FT: P < 0.0001; severe FT: P = 0.0033). Volunteers with normal FJ orientation showed significantly higher gagCEST values compared to those with sagittal FJ orientation >45° (P < 0.001). We found a significant, negative correlation between gagCEST values and higher angels in sagittal FJ orientation (rho = -0.459; P < 0.0001). CONCLUSION: GagCEST analysis indicated lower GAG values of NP in young volunteers with FT and sagittal orientated FJ, indicating that FT and sagittal orientation of the FJ represent risk factors for the development of early biochemical alterations of lumbar IVDs.

[Functional magnetic resonance imaging of the kidneys]. / Funktionelle Magnetresonanztomographie der Nieren.

Interest in functional renal magnetic resonance imaging (MRI) has significantly increased in recent years. This review article provides an overview of the most important functional imaging techniques and their potential clinical applications for assessment of native and transplanted kidneys, with special emphasis on the clarification of renal tumors.

Correlation of the apparent diffusion coefficient (ADC) with the standardized uptake value (SUV) in hybrid 18F-FDG PET/MRI in non-small cell lung cancer (NSCLC) lesions: initial results.

PURPOSE: To compare the apparent diffusion coefficient (ADC) in non-small cell lung cancer lesions with standardized uptake values (SUV) derived from combined 18F-fluoro-deoxy-glucose-positron emission tomography/magnetic resonance imaging (FDG-PET/MRI) and those derived from FDG-PET/CT. MATERIALS AND METHODS: In 18 consecutive patients with histologically proven NSCLC (17 men, 1 woman; mean age, 61 ± 12 years), whole-body FDG-PET/MRI was performed after whole-body FDG-PET/CT. Regions of interest (ROI) encompassing the entire primary tumor were drawn into FDG-PET/CT and FDG-PET/MR images to determine the maximum and mean standardized uptake value (SUVmax; SUVmean) and into ADC parameter maps to assess mean ADC values. Pearson's correlation coefficients were calculated to compare SUV and ADC values. RESULTS: The SUVmax of NSCLC was 12.3 ± 4.8 [mean ±SD], and the SUVmean was 7.2 ± 2.8 as assessed by FDG-PET/MRI. The SUVmax and SUVmean derived from FDG-PET/CT and FDG-PET/MRI correlated well (R = 0.93; p < 0.001 and R = 0.92; p < 0.001, respectively). The ADCmean of the pulmonary tumors was 187.9 ± 88.8 × 10-5 mm²/s [mean ± SD]. The ADCmean exhibited a significant inverse correlation with the SUVmax (R = -0.72; p < 0.001) as well as with the SUVmean assessed by FDG-PET/MRI (R = -0.71; p < 0.001). CONCLUSION: This simultaneous PET/MRI study corroborates the assumed significant inverse correlation between increased metabolic activity on FDG-PET and restricted diffusion on DWI in NSCLC.Citation Format:

Processing of subliminal facial expressions of emotion: a behavioral and fMRI study.

The recognition of emotional facial expressions is an important means to adjust behavior in social interactions. As facial expressions widely differ in their duration and degree of expressiveness, they often manifest with short and transient expressions below the level of awareness. In this combined behavioral and fMRI study, we aimed at examining whether or not consciously accessible (subliminal) emotional facial expressions influence empathic judgments and which brain activations are related to it. We hypothesized that subliminal facial expressions of emotions masked with neutral expressions of the same faces induce an empathic processing similar to consciously accessible (supraliminal) facial expressions. Our behavioral data in 23 healthy subjects showed that subliminal emotional facial expressions of 40 ms duration affect the judgments of the subsequent neutral facial expressions. In the fMRI study in 12 healthy subjects it was found that both, supra- and subliminal emotional facial expressions shared a widespread network of brain areas including the fusiform gyrus, the temporo-parietal junction, and the inferior, dorsolateral, and medial frontal cortex. Compared with subliminal facial expressions, supraliminal facial expressions led to a greater activation of left occipital and fusiform face areas. We conclude that masked subliminal emotional information is suited to trigger processing in brain areas which have been implicated in empathy and, thereby in social encounters.

Structural white matter changes in adolescents and young adults with maple syrup urine disease.

OBJECTIVE: To get insight into the nature of magnetic resonance (MR) white matter abnormalities of patients with classic maple syrup urine disease (MSUD) under diet control. METHODS: Ten patients with classic MSUD and one with a severe MSUD variant (mean age 21.5 ± 5.1 years) on diet and 11 age and sex-matched healthy subjects were enrolled. Apart from standard MR sequences, diffusion weighted images (DWI), diffusion tensor images (DTI), and magnetization transfer images (MT) were obtained and comparatively analyzed for apparent diffusion coefficient (ADC), tensor fractional anisotropy (FA) and MT maps in 11 regions of interest (ROI) within the white matter. RESULTS: In MSUD patients DWI, DTI and FA showed distinct signal changes in the cerebral hemispheres, the dorsal limb of internal capsule, the brain stem and the central cerebellum. Signal intensity was increased in DWI with a reduced ADC and decreased values for FA. MT did not reveal differences between patients and control subjects. CONCLUSION: Signal abnormalities in the white matter of adolescents and young adults under diet control may be interpreted as consequence of structural alterations like dysmyelination. The reduced ADC and FA in the white matter with preserved MT indicate a reduction in fiber tracks.

The neural correlates of affect reading: an fMRI study on faces and gestures.

As complex social beings, people communicate, in addition to spoken language, also via nonverbal behavior. In social face-to-face situations, people readily read the affect and intentions of others in their face expressions and gestures recognizing their meaning. Importantly, the addressee further has to discriminate the meanings of the seen communicative motor acts in order to be able to react upon them appropriately. In this functional magnetic resonance imaging study 15 healthy non-alexithymic right-handers observed video-clips that showed the dynamic evolution of emotional face expressions and gestures evolving from a neutral to a fully developed expression. We aimed at disentangling the cerebral circuits related to the observation of the incomplete and the subsequent discrimination of the evolved bodily expressions of emotion which are typical for everyday social situations. We show that the inferior temporal gyrus and the inferior and dorsal medial frontal cortex in both cerebral hemispheres were activated early in recognizing faces and gestures, while their subsequent discrimination involved the right dorsolateral frontal cortex. Interregional correlations showed that the involved regions constituted a widespread circuit allowing for a formal analysis of the seen expressions, their empathic processing and the subjective interpretation of their contextual meanings. Right-left comparisons revealed a greater activation of the right dorsal medial frontal cortex and the inferior temporal gyrus which supports the notion of a right hemispheric dominance for processing affective body expressions. These novel data provide a neurobiological basis for the intuitive understanding of other people which is relevant for socially appropriate decisions and intact social functioning.

Peripheral blood levels of matrix metalloproteinase-9 predict lesion volume in acute stroke.

Matrix metalloproteinases (MMPs) have been implicated to play an important role in the destruction of the extracellular matrix in diseases of the central nervous system. This study investigated whether the expression of one of these proteases, MMP-9 in blood, is related to the size of human brain infarcts assessed with magnetic resonance imaging. Consecutively, twenty-one acute stroke patients were included prospectively into our study. In blood samples drawn within 24 h after onset, MMP-9 RNA-expression and proteolytic-activity were analyzed by quantitative polymerase chain reaction and gelatin zymography, respectively. The ischemic lesion volumes in time to peak perfusion maps and diffusion weighted imaging were measured morphometrically. RNA-expression levels of MMP-9 in peripheral blood mononuclear cells (PBMCs) correlated with the brain infarct lesion (TTP-delay 4 s, r = -0.61, p = 0.007; TTP-delay 6 s: r = -0.58, p = 0.012; DWI r = -0.47; p = 0.047). Our preliminary results demonstrate that MMP-9 RNA is upregulated in PBMCs in proportion to ischemia. These findings suggest that MMP-9 might contribute to the manifestation of ischemic brain damage. Since MMP-9 is upregulated in acute ischemia inhibition of MMP-9 may represent a complementary treatment target in acute stroke therapy.

Arterial spin labelling perfusion MRI of breast cancer using FAIR TrueFISP: initial results.

AIM: To assess the feasibility of an unenhanced, flow-sensitive, alternating inversion recovery-balanced steady-state free precession (FAIR TrueFISP) arterial spin labelling (ASL) magnetic resonance imaging (MRI) technique for quantification of breast cancer perfusion. MATERIALS AND METHODS: Eighteen untreated breast tumour patients (mean age 53 ± 17 years, range 30-68 years) and four healthy controls (mean age 51 ± 14 years, range 33-68 years) were enrolled in this study and were imaged using a clinical 1.5 T MRI machine. Perfusion measurements were performed using a coronal single-section ASL FAIR TrueFISP technique in addition to a routine breast MRI examination. T1 relaxation time of normal breast parenchyma was determined in four healthy volunteers using the variable flip angle approach. The definitive diagnosis was obtained at histology after biopsy or surgery and was available for all patients. RESULTS: ASL perfusion was successfully acquired in 13 of 18 tumour patients and in all healthy controls. The mean ASL perfusion of invasive ductal carcinoma tissue was significantly higher (88.2 ± 39.5 ml/100 g/min) compared to ASL perfusion of normal breast parenchyma (24.9 ± 12.7 ml/100 g/min; p < 0.05) and invasive lobular carcinoma (30.5 ± 4.3 ml/100 g/min; p < 0.05). No significant difference was found between the mean ASL perfusion of normal breast parenchyma and invasive lobular carcinoma tissue (p = 0.97). CONCLUSION: ASL MRI enables quantification of breast cancer perfusion without the use of contrast material. However, its impact on diagnosis and therapy management of breast tumours has to be evaluated in larger patient studies.

Nonenhanced ECG-gated time-resolved 4D steady-state free precession (SSFP) MR angiography (MRA) of cerebral arteries: comparison at 1.5T and 3T.

PURPOSE: To compare image quality of nonenhanced time-resolved 4D steady-state free precession MR angiography (4D SSFP MRA) of cerebral arteries at 1.5T and 3T. MATERIALS AND METHODS: 12 healthy subjects (mean age 29.4±6.9 years) were studied at both 1.5T and 3T. Two different positions of the acquisition slab were evaluated; in one acquisition the imaging slab included the carotid siphon ("S(low)"), in the other acquisition the imaging slab was placed superior to the carotid siphon ("S(high)"). Subjective image quality of cerebral arteries was assessed independently by two readers on a 4-point scale. Relative Signal-to-Noise-Ratio (SNR) was determined for the M1 segment of the middle cerebral artery. RESULTS: Subjective image quality of the anterior cerebral artery (segments A1, A2) was significantly higher at 1.5T as compared to 3T, while 3T provided significantly higher image quality for segment P3 of the posterior cerebral artery. For the middle cerebral artery (segments M1-M3), image quality was significantly higher at 1.5T than at 3T when the carotid siphon was included in the acquisition slab ("S(low)"), while no significant difference was found between 1.5T and 3T with "S(high)". Relative SNR was significantly higher at 1.5T (23.1±5.1) as compared to 3T (12.1±7.8) for "S(low)" and significantly higher at 3T (29.8±5.9) than at 1.5T (24.2±3.6) for "S(high)". CONCLUSION: Our results indicate that 4D SSFP MRA should preferably be performed at 1.5T with inclusion of the carotid siphon in the acquisition slab, which might be required for the assessment of intracranial collateral flow.

Nonenhanced ECG-gated quiescent-interval single-shot MRA (QISS-MRA) of the lower extremities: comparison with contrast-enhanced MRA.

AIM: To evaluate electrocardiogram (ECG)-gated quiescent-interval single-shot magnetic resonance angiography (QISS-MRA) for nonenhanced assessment of peripheral artery occlusive disease (PAOD) using contrast-enhanced MRA (CE-MRA) as the reference standard. MATERIALS AND METHODS: Twenty-seven patients (mean age 66.6 ± 10.8 years) with PAOD were included in the study. QISS-MRA and CE-MRA of the lower extremity were performed using a 1.5 T MR scanner. In each patient, subjective image quality and the degree of stenosis were evaluated on a four-point scale for 15 predefined arterial segments. RESULTS: Twenty-five of the 27 patients were considered for analysis. Subjective image quality of QISS-MRA was significantly lower for the distal aorta, pelvic arteries, and femoral arteries as compared to CE-MRA (p < 0.01), while no significant difference was found for other vascular segments. The degree of stenosis was overestimated with QISS-MRA in 23 of 365 (6.3%) segments and underestimated in two of 365 (0.5%) segments. As compared to CE-MRA, QISS-MRA had a high sensitivity (98.6%), specificity (96%) as well as positive and negative predictive value (88.7 and 99.6%, respectively) for the detection of significant stenosis (≥50%). CONCLUSION: ECG-gated QISS-MRA is a promising imaging technique for reliable assessment of PAOD without the use of contrast material.

T2' Imaging of Native Kidneys and Renal Allografts - a Feasibility Study.

PURPOSE: To evaluate the feasibility of T2' mapping in native kidneys and renal allografts. MATERIALS AND METHODS: Following approval of the local ethics committee, 24 renal allograft recipients and 10 control subjects (healthy volunteers) were included in this study. Multi-echo T2 and T2* imaging was performed on a 1.5 Tesla scanner. Allograft recipients were assigned to two groups: group a), 8 patients with good (glomerular filtration rate of more than 40 ml/min) allograft function and no evidence of transplant rejection, transplant renal artery stenosis or ureteral obstruction; group b), 16 patients with deterioration of renal graft function (glomerular filtration rate (GFR) of 40 ml/min or less). Two different imaging protocols were tested. RESULTS: The mean T2' relaxation parameters were 108.33 msec ± 13.34, 100.00 msec ± 18.89 and 124.57 msec ± 6.51 for groups a), b) and for control subjects, respectively. The reduction of T2' values in patient group b) was not statistically significant. However, significant correlations could be demonstrated between T2' values and the glomerular filtration rate (GFR) of renal allograft function. The reproducibility was tested and the coefficients of variation of T2' values in the cortex of transplanted kidneys were 11.1% within subjects and 11.3% between subjects. CONCLUSION: Our results indicate that T2' imaging is a promising non-enhanced technique, which seems to reveal information on transplant function. Further studies are required to determine the clinical value of T2' mapping for monitoring renal allograft recipients.

[Cartilage quality in finger joints: delayed Gd(DTPA)²-enhanced MRI of the cartilage (dGEMRIC) at 3T]. / Knorpelqualität an den Fingergelenken: delayed Gd(DTPA)²-enhanced MRI of the cartilage (dGEMRIC) bei 3T.

PURPOSE: To evaluate the feasibility of molecular cartilage MRI in finger joints. MATERIALS AND METHODS: Delayed Gd(DTPA)²-enhanced MRI of the cartilage (dGEMRIC) using a variable flip angle approach (VFA) was performed for the metacarpophalangeal (MCP) joints II and III in nine healthy volunteers and eighteen patients with rheumatoid arthritis (RA). The cartilage thickness was measured. Additionally, dGEMRIC was performed on proximal interphalangeal joints (PIP) in two patients with finger osteoarthritis (OA). RESULTS: the dGEMRIC index of the four evaluated cartilage areas was significantly decreased in RA patients compared to healthy subjects. The dGEMRIC index of MCP II phalangeal cartilage was 389.6 ± 85.5 msec vs. 558.7 ± 74.4 msec in healthy subjects. The metacarpal MCP II cartilage dGEMRIC index was 357.3 msec ± 97.1 msec vs. 490.0 ± 86.6 msec. The dGEMRIC indices of MCP III were: phalangeal 436.2 ± 113.6 msec in RA, 558.8 ± 115.5 msec in healthy subjects and metacarpal 398.0 ± 97.6 msec in RA and 529.6 ± 111.0 msec in healthy subjects. Age and cartilage thickness were not significantly different. In PIP joints of finger osteoarthritis patients, low dGEMRIC indices were noted, compared to the controls. CONCLUSION: The dGEMRIC of finger joints is feasible in patients with RA and finger OA. Morphologically normal cartilage shows significantly decreased dGEMRIC values in RA, pointing towards cartilage degeneration on a molecular level. Further studies are needed to establish the usefulness of this technique for early diagnosis, prognosis and therapy monitoring.

A novel MRI-biomarker candidate for Alzheimer's disease composed of regional brain volume and perfusion variables.

BACKGROUND: Earlier evidence indicates that regional cerebral volume (rVOL) and blood flow (rCBF) variables carry independent information on incipient and early Alzheimer's disease (AD) and combining these modalities may increase discriminant performance. We compared single variables and combinations regarding their power for optimizing diagnostic accuracy. METHODS: Twelve cognitively normal elderly controls (CN), 30 subjects with mild cognitive impairment (MCI) and 15 with mild AD were examined by structural and perfusion-weighted magnetic resonance imaging (MRI) in single sessions at 1.5 Tesla. rVOLs were measured by manual volumetry, and rCBFs were calculated with a ROI-based co-localization technique. RESULTS: Applying single MRI variables for the differentiation of AD versus CN, the area under curve (AUC) of receiver operating characteristic curves (ROCCs) was highest for rVOL variables (maximum of 0.972 for right amygdala). A composite marker selected and weighted by logistic regression containing left amygdalar rCBF, left hippocampal and right amygdalar rVOLs gave a diagnostic accuracy for AD versus CN of 100%. Internal cross-validation revealed a reliability of 88.9%. CONCLUSIONS: Whilst external revalidation is mandatory employing a naturalistic sample containing disease controls, our phase I/II findings demonstrate that deducing composite markers from multimodal MRI acquisitions can optimize diagnostic accuracy for AD.

Brain activation patterns underlying fast habituation to painful laser stimuli.

A painful experience is modified by processes like habituation/antinociception or sensitization. Altered habituation may be one characteristic of chronic pain syndromes. In the present study we sought to investigate the functional magnetic resonance imaging (fMRI) blood oxygen level dependent (BOLD) correlate of rapid habituation to pain using simultaneous single trial electrodermal activity (EDA)/fMRI measurements. A total of N=32 healthy subjects have been investigated. Subjects received painful laser stimulation of the left hand. The fMRI BOLD response was measured simultaneously with continuous EDA recordings. Single trial EDA responses to laser stimulation habituated over time with substantial subject-to-subject differences in the degree and speed of habituation. fMRI BOLD habituation was assessed by contrasting the first half of the experiment against the second half and was found in primary and secondary somatosensory cortices, the insula and the anterior cingulate cortex (ACC). We hypothesized that single trial EDA habituation would reflect BOLD habituation which was investigated separately in subjects with 'faster' (N=15) and 'slower' (N=14) EDA habituation. Significant habituation of the BOLD signal was only found in subjects with 'faster' EDA habituation that was accompanied by a signal increase in the rostral ACC and the periaqueductal grey. Furthermore, subjects with faster EDA habituation provided lower pain ratings. Therefore the EDA habituation profile to painful stimulation may constitute a pain-related (endo)phenotype and may be an informative additional endpoint measure in fMR-imaging of pain, especially when people suffering from chronic pain states in which pain processing is often altered are studied.

[Functional MRI of transplanted kidneys using diffusion-weighted imaging]. / Funktionelle MRT der Transplantatnieren: klinische Wertigkeit der Diffusionsbildgebung.

PURPOSE: Contrast-enhanced MRI is considered problematic in renal allograft recipients due to the association of gadolinium administration and the development of NSF. Therefore, we assessed the clinical value of mono- and biexponential analysis of diffusion-weighted imaging (DWI). MATERIALS AND METHODS: A total of 32 patients were divided into four groups: (a) patients with stable function of renal allograft for at least 6 months, (b) patients with acute deterioration of allograft function, patients who recently underwent transplantation (< 14 days) with good (c) or decreased (d) renal function. T 2w ax. and T 1w cor. and a diffusion-weighted sequence with 16 b-values (b = 0 - 750 s/mm (2)) were performed on a 1.5 T scanner (Magnetom Avanto, Siemens Medical Solutions). ROI-based analysis of the renal cortex was analyzed using the software "Table Curve 2D". RESULTS: Monoexponential analysis showed an ADC (mono) of 1961 +/- 104 1801 +/- 150, 2053 +/- 169 and 1720 +/- 191 10 (-6)mm (2) /sec for patient group a, b, c and d respectively. The difference in ADC (mono) between group (a) and (b) (p < 0.006) and between group (c) and (d) (p < 0.04) was statistically significant. Biexponential analysis revealed a mean perfusion fraction of 0.21, 0.23, 0.32 and 0.24 for group (a), (b), (c) and (d), respectively. Biexponential ADC showed a higher numerical accuracy. There were no statistically significant inter-group differences in diffusion (ADC (D)) and perfusion (ADC (P)). CONCLUSION: Unenhanced evaluation of renal allografts with DWI is feasible. ADC (mono) of renal cortex correlates with renal function. The significance of the higher numerical accuracy of biexponential analysis in clinical settings requires further evaluation in larger-scale studies.