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Nephrology 01/2013; 18(1):75-6. · 1.31 Impact Factor
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Christian Buchbender,
Benedikt Ostendorf,
Katalin Mattes-György,
Falk Miese,
Hans-Joerg Wittsack, Michael Quentin,
Christof Specker,
Matthias Schneider,
Gerald Antoch,
Hans-Wilhelm Müller,
Axel Scherer
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ABSTRACT: PURPOSE: We aimed to assess the relationship between bone inflam- mation in multi-pinhole single-photon emission computed tomography (MPH-SPECT) and synovitis detected by mag- netic resonance imaging (MRI) in early rheumatoid arthritis patients. MATERIALS AND METHODS: MPH-SPECT with technetium-99m dicarboxypropanedis- phosphonate (Tc-99m DPD) and 3 Tesla MRI were performed in 10 early rheumatoid arthritis patients. Eighty finger joint sites were assessed for increased osteoblastic activity using visual and region-of-interest (ROI) analysis. Presence of joint inflammation in MRI was investigated using the subscores of the rheumatoid arthritis MRI score. RESULTS: Tc-99m DPD uptake was increased in 38 (47.5%) and 22 (27.5%) joint sites as determined by visual and ROI analysis, respectively. A total of 32 (84.2%) sites with increased bone metabolism showed a normal MRI bone signal. The MPH- SPECT uptake ratio was elevated only in the subgroup with severe synovitis (P < 0.001). CONCLUSION: In early rheumatoid arthritis, molecular imaging with MPH- SPECT detects higher rates of inflammatory bone involve- ment compared to MRI. Our preliminary data suggest that osteitis is related to severe synovitis.
Diagnostic and interventional radiology (Ankara, Turkey) 12/2012; · 1.10 Impact Factor
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ABSTRACT: PURPOSE: To evaluate which mathematical model (monoexponential, biexponential, statistical, kurtosis) fits best to the diffusion-weighted signal in prostate magnetic resonance imaging (MRI). MATERIALS AND METHODS: 24 prostate 3-T MRI examinations of young volunteers (YV, n=8), patients with biopsy proven prostate cancer (PC, n=8) and an aged matched control group (AC, n=8) were included. Diffusion-weighted imaging was performed using 11 b-values ranging from 0 to 800 s/mm(2). RESULTS: Monoexponential apparent diffusion coefficient (ADC) values were significantly (P<.001) lower in the peripheral (PZ) zone (1.18±0.16 mm(2)/s) and the central (CZ) zone (0.73±0.13 mm(2)/s) of YV compared to AC (PZ 1.92±0.17 mm(2)/s; CZ 1.35±0.21 mm(2)/s). In PC ADC(mono) values (0.61±0.06 mm(2)/s) were significantly (P<.001) lower than in the peripheral of central zone of AC. Using the statistical analysis (Akaike information criteria) in YV most pixels were best described by the biexponential model (82%), the statistical model, respectively kurtosis (93%) each compared to the monoexponential model. In PC the majority of pixels was best described by the monoexponential model (57%) compared to the biexponential model. CONCLUSION: Although a more complex model might provide a better fitting when multiple b-values are used, the monoexponential analyses for ADC calculation in prostate MRI is sufficient to discriminate prostate cancer from normal tissue using b-values ranging from 0 to 800 s/mm(2).
Magnetic Resonance Imaging 07/2012; · 1.99 Impact Factor
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ABSTRACT: PURPOSE: To evaluate the impact of renal blood flow on apparent diffusion coefficients (ADC) and fractional anisotropy (FA) using time-resolved electrocardiogram (ECG)-triggered diffusion-tensor imaging (DTI) of the human kidneys. MATERIALS AND METHODS: DTI was performed in eight healthy volunteers (mean age 29.1 ± 3.2) using a single slice coronal echoplanar imaging (EPI) sequence (3 b-values: 0, 50, and 300 s/mm(2) ) at the timepoint of minimum (20 msec after R wave) and maximum renal blood flow (200 msec after R wave) at 3T. Following 2D motion correction, region of interest (ROI)-based analysis of cortical and medullary ADC- and FA-values was performed. RESULTS: ADC-values of the renal cortex at maximum blood flow (2.6 ± 0.19 × 10(-3) mm(2) /s) were significantly higher than at minimum blood flow (2.2 ± 0.11 × 10(-3) mm(2) /s) (P < 0.001), while medullary ADC-values did not differ significantly (maximum blood flow: 2.2 ± 0.18 × 10(-3) mm(2) /s; minimum blood flow: 2.15 ± 0.14 × 10(-3) mm(2) /s). FA-values of the renal medulla were significantly greater at maximal blood (0.53 ± 0.05) than at minimal blood flow (0.47 ± 0.05) (P < 0.01). In contrast, cortical FA-values were comparable at different timepoints of the cardiac cycle. CONCLUSION: ADC-values in the renal cortex as well as FA-values in the renal medulla are influenced by renal blood flow. This impact has to be considered when interpreting renal ADC- and FA-values. J. Magn. Reson. Imaging 2012;. © 2012 Wiley Periodicals, Inc.
Journal of Magnetic Resonance Imaging 07/2012; · 2.70 Impact Factor
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ABSTRACT: Patients with previous negative transrectal ultrasound-guided biopsy (TRUS-GB) and persistently increased prostate-specific antigen (PSA) value represent a great diagnostic problem. Magnetic resonance imaging (MRI)-guided biopsy demonstrates high prostate cancer detection rates in these patients if functional MRI is suspicious for prostate cancer. However, MRI-guided biopsy is not commonly available and features considerable technical requirements. This was a pilot study to investigate if a standard repeat TRUS-GB, with additional targeted cores to suspicious lesions on functional MRI, can achieve similar detection rates as compared to MRI-guided biopsy.
3 Tesla functional MRI was performed in 58 patients with ≥1 previous negative biopsy, persistently increased PSA ≥4 ng/ml and unsuspicious digital rectal examination. Suspicious lesions were marked on a localization map to enable their finding on TRUS. Random TRUS-GB with additional targeted cores according to the functional MRI findings were performed in patients with ≥1 suspicious lesion.
In 37.9% (22/58), functional MRI demonstrated suspicious findings. Out of these 22 patients, 16 underwent TRUS-GB with additional targeted cores. Prostate cancer was diagnosed in 68.8% (11/16). Eight out of these 11 patients subsequently underwent radical prostatectomy and all tumors fulfilled criteria for high-risk prostate cancer. With a median follow-up of 49.1 weeks neither significant PSA increase nor prostate cancer was detected in patients with normal functional MRI findings.
Our approach enables excellent detection rates of clinically significant prostate cancer in patients with ≥1 previous negative biopsy and persistently increased PSA levels. Due to the current disadvantages of MRI-guided biopsy, our approach therefore represents an excellent alternative to MRI-guided biopsy.
Anticancer research 03/2012; 32(3):1087-92. · 1.73 Impact Factor
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ABSTRACT: To evaluate the influence of pulsatile blood flow on apparent diffusion coefficients (ADC) and the fraction of pseudodiffusion (F(P)) in the human kidney.
The kidneys of 6 healthy volunteers were examined by a 3-T magnetic resonance scanner. Electrocardiogram (ECG)-gated and respiratory-triggered diffusion-weighted imaging (DWI) and phase-contrast flow measurements were performed. Flow imaging of renal arteries was carried out to quantify the dependence of renal blood flow on the cardiac cycle. ECG-triggered DWI was acquired in the coronal plane with 16 b values in the range of 0 s/mm(2) and 750 s/mm(2) at the time of minimum (MIN) (20 milliseconds after R wave) and maximum renal blood flow (MAX) (197 ± 24 milliseconds after R wave). The diffusion coefficients were calculated using the monoexponential approach as well as the biexponential intravoxel incoherent motion model and correlated to phase-contrast flow measurements.
Flow imaging showed pulsatile renal blood flow depending on the cardiac cycle. The mean flow velocity at MIN was 45 cm/s as compared with 61 cm/s at MAX. F(p) at MIN (0.29) was significantly lower than at MAX (0.40) (P = 0.001). Similarly, ADC(mono), derived from the monoexponential model, also showed a significant difference (P < 0.001) between MIN (ADC(mono) = 2.14 ± 0.08 × 10(-3) mm(2)/s) and MAX (ADC(mono) = 2.37 ± 0.04 × 10(-3) mm(2)/s). The correlation between renal blood flow and F(p) (r = 0.85) as well as ADC(mono) (r = 0.67) was statistically significant.
Temporally resolved ECG-gated DWI enables for the determination of the diffusion coefficients at different time points of the cardiac cycle. ADC(mono) and FP vary significantly among acquisitions at minimum (diastole) and maximum (systole) renal blood flow. Temporally resolved ECG-gated DWI might therefore serve as a novel technique for the assessment of pulsatility in the human kidney.
Investigative radiology 11/2011; 47(4):226-30. · 4.85 Impact Factor
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Christian Buchbender,
Axel Scherer,
Patric Kröpil,
Birthe Körbl, Michael Quentin,
Dorothea Ch Reichelt,
Rotem S Lanzman,
Christian Mathys,
Dirk Blondin,
Bernd Bittersohl,
Christoph Zilkens,
Matthias Hofer,
Hans-Jörg Wittsack,
Matthias Schneider,
Gerald Antoch,
Benedikt Ostendorf,
Falk Miese
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ABSTRACT: To prospectively evaluate four non-invasive markers of cartilage quality--T2* mapping, native T1 mapping, dGEMRIC and ΔR1--in healthy volunteers and rheumatoid arthritis (RA) patients.
Cartilage of metacarpophalangeal (MCP) joints II were imaged in 28 consecutive subjects: 12 healthy volunteers [9 women, mean (SD) age 52.67 (9.75) years, range 30-66] and 16 RA patients with MCP II involvement [12 women, mean (SD) age 58.06 (12.88) years, range 35-76]. Sagittal T2* mapping was performed with a multi-echo gradient-echo on a 3 T MRI scanner. For T1 mapping the dual flip angle method was applied prior to native T1 mapping and 40 min after gadolinium application (delayed gadolinium-enhanced MRI of cartilage, dGEMRIC, T1(Gd)). The difference in the longitudinal relaxation rate induced by gadolinium (ΔR1) was calculated. The area under the receiver operating characteristic curve (AROC) was used to test for differentiation of RA patients from healthy volunteers.
dGEMRIC (AUC 0.81) and ΔR1 (AUC 0.75) significantly differentiated RA patients from controls. T2* mapping (AUC 0.66) and native T1 mapping (AUC 0.66) were not significantly different in RA patients compared to controls.
The data support the use of dGEMRIC for the assessment of MCP joint cartilage quality in RA. T2* and native T1 mapping are of low diagnostic value. Pre-contrast T1 mapping for the calculation of ΔR1 does not increase the diagnostic value of dGEMRIC.
Skeletal Radiology 09/2011; 41(6):685-92. · 1.54 Impact Factor
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ABSTRACT: Biopsies guided by computed tomography (CT) play an important role in clinical practice. A short duration, minimal radiation dose and complication rate are of particular interest. Purpose To evaluate the potential of a novel self-manufactured wire-based needle guide device for CT-guided thoracic biopsies with respect to radiation dose, intervention time and complication rate.
Forty patients that underwent CT-guided biopsies of thoracic lesions were included in this study and assigned to two groups. Patients in group A (n = 20, mean age 69 ± 8.4 years) underwent biopsies with a novel wire-based needle guide device, while patients in group B (n = 20, mean age 68.4 ± 10.1 years) were biopsied without a needle guide device. The novel self-manufactured needle guide device consists of an iron/zinc wire modelled to a ring with a flexible arm and an eye at the end of the arm to stabilize the biopsy needle in the optimal position during intervention. Predefined parameters (radiation dose, number of acquired CT-slices, duration of intervention, complications) were compared between both groups.
Mean radiation dose (CTDIvol 192 mGy versus 541 mGy; P ≤ 0.001) and the number of acquired slices during intervention (n = 49 ± 33 vs. n = 126 ± 78; P ≤ 0.001) were significantly lower in group A compared with group B. Intervention time in group A (13.1 min) was significantly lower than in group B (18.5 min, P < 0.01). A pneumothorax as peri-interventional complication was observed less frequent after device assisted biopsies (n = 4 vs. n = 8, n.s.).
The novel wire-based needle guide device is a promising tool to facilitate CT-guided thoracic biopsies reducing radiation dose, intervention time, and related complications. Further studies are mandatory to confirm these initial results.
Acta Radiologica 08/2011; 52(8):866-70. · 1.37 Impact Factor
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Falk Miese,
Patric Kröpil,
Benedikt Ostendorf,
Axel Scherer,
Christian Buchbender, Michael Quentin,
Rotem S Lanzman,
Dirk Blondin,
Matthias Schneider,
Bernd Bittersohl,
Christoph Zilkens,
Vladimir Jellus,
Tallal Ch Mamisch,
Hans-Jörg Wittsack
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ABSTRACT: To assess motion artifacts in dGEMRIC of finger joints and to evaluate the effectiveness of motion correction.
In 40 subjects (26 patients with finger arthritis and 14 healthy volunteers) dGEMRIC of metacarpophalangeal joint II was performed. Imaging used a dual flip angle approach (TE 3.72 ms, TR 15 ms, flip angles 5° and 26°). Two sets of T1 maps were calculated for dGEMRIC analysis from the imaging data for each subject: one with and one without motion correction. To compare image quality, visual grading analysis and precision of dGEMRIC measurement of both dGEMRIC maps for each case were evaluated.
Motion artifacts were present in 82% (33/40) of uncorrected dGEMRIC maps. Motion artifacts were graded as severe or as rendering evaluation impossible in 43% (17/40) of uncorrected dGEMRIC maps. Motion corrected maps showed significantly less motion artifacts (P<0.001) and were graded as evaluable in 97% (39/40) of cases. Precision was significantly higher in motion corrected images (coefficient of variation (CV=.176±.077), compared to uncorrected images (CV .445±.347) (P<.001). Motion corrected dGERMIC was different in volunteers and patients (P=.044), whereas uncorrected dGEMRIC was not (P=.234).
Motion correction improves image quality, dGEMRIC measurement precision and diagnostic performance in dGEMRIC of finger joints.
European journal of radiology 02/2011; 80(3):e427-31. · 2.65 Impact Factor
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Hepatology 09/2010; 52(3):1167-8. · 11.66 Impact Factor
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ABSTRACT: In the heart, there is not only a transmural gradient of left ventricular perfusion and action potential duration (APD), but also spatial heterogeneity within each myocardial layer, where local blood flow and energy turnover vary more than three-fold between individual regions. We analysed at high spatial resolution whether a corresponding heterogeneity also extends to ion channel gene expression and APD.
In the open-chest beagle dog, left ventricular 300 microL samples of very low or high flow were identified by radioactive microspheres and expression levels determined by quantitative PCR. The distribution of epicardial APD was assessed by mapping local activation repolarization intervals (ARIs) and QT interval (QT). ERG, the potassium channel mediating IKr, and KChIP2, the interacting protein modulating Ito, were increased in Low flow (3.3- and 2.5-fold, P < 0.001 and <0.05, respectively; n = 6 hearts, 30-31 samples each) as compared with High flow areas. This suggested enhanced repolarizing currents in Low flow areas, and in consequence, mathematical model analysis predicted a shorter local APD upon enhanced ERG and IKr. Epicardial mapping revealed a patchy, temporally stable APD pattern (n = 11), a small apico-basal gradient and an APD prolongation induced by the ERG blocker dofetilide predominantly in areas of short basal ARI or QT, respectively (n = 9). In addition, in Short QT areas, ERG expression was three-fold increased (P < 0.05, n = 4).
The spatial pattern of perfusion is matched by the novel patterns of K+ channel expression and APD. Whenever this newly recognized intramural dispersion of APD increases, it may contribute to arrhythmogenesis.
Cardiovascular Research 02/2008; 77(3):489-96. · 6.06 Impact Factor
