Multi-vendor multi-site quantitative MRI analysis of cartilage degeneration 10 Years after anterior cruciate ligament reconstruction: MOON-MRI protocol and preliminary results

OBJECTIVE

To describe the protocol of a multi-vendor, multi-site quantitative MRI study for knee post-traumatic osteoarthritis (PTOA), and to present preliminary results of cartilage degeneration using MR T1ρ and T2 imaging 10 years after anterior cruciate ligament reconstruction (ACLR).

DESIGN

This study involves three sites and two MR platforms. The patients are from a nested cohort (termed as Onsite cohort) within the Multicenter Orthopaedic Outcomes Network (MOON) cohort 10 years after ACLR. Phantoms and controls were scanned for evaluating reproducibility. Cartilage was automatically segmented, and T1ρ and T2 were compared between operated, contralateral, and control knees.

RESULTS

Sixty-eight ACL-reconstructed patients and 20 healthy controls were included. In phantoms, the intra-site coefficients of variation (CVs) of repeated scans ranged 1.8-2.1% for T1ρ and 1.3-1.7% for T2. The inter-site CVs ranged 1.6-2.1% for T1ρ and 1.1-1.4% for T2. In human subjects, the intra-site scan/rescan CVs ranged 2.2-3.5% for T1ρ and 2.6-4.9% for T2 for the six major compartments. In patients, operated knees showed significantly higher T1ρ and T2 values mainly in medial femoral condyle, medial tibia and trochlear cartilage compared with contralateral knees, and showed significantly higer T1ρ and T2 values in all six compartments compared to healthy control knees. The patient contralateral knees showed higher T1ρ and T2 values mainly in the lateral femoral condyle, lateral tibia, trochlear, and patellar cartilage compared to healthy control knees.

CONCLUSION

A platform and workflow with rigorous quality control has been established for a multi-vendor multi-site quantitative MRI study in evaluating PTOA 10 years after ACLR. Our preliminary report suggests significant cartilage matrix changes in both operated and contralateral knees compared with healthy control knees.

Diagnostic Evaluation of the Breast Using PET: Optimization of Data Acquisition and Postprocessing

Purpose: Development and evaluation of an optimized protocol for PET examinations of the female breast with 2-F-l8-fluoro-2-deoxyglucose (F-18-FDG). Methods: All PET measurements were performed with a whole-body PET system (ECAT EXACT HR+). In order to examine the women with the breasts freely pendant, a special extension for the patient table made of carbon layer composite was designed. After data acquisition in the 3D modus, emission data were sorted into 2D sinograms using the Fourier rebinning algorithm and reconstructed by means of an ultra-fast iterative 2D algorithm (HOSP). The reconstructed emission scans were superimposed onto the corresponding transmission images. The protocol presented was evaluated in examinations on 6 women with breast lesions after the administration of 150-220 MBq F-l8-FDG. From two adjacent bed positions, emission and transmission data were acquired over periods of 20 min and 10 min, respectively. For comparison, dynamic magnetic resonance (MR) image series were acquired with a whole-body MR system (MAGNET0M SP 4000) using a double-breast coil. Results and Conclusion: Using the designed extension of the patient table, it was possible to examine corpulent women despite the limited patient port of the PET system in the prone position with the breasts freely pendant. Alongside a reduction in motion artifacts, this positioning also offers the possibility of making a direct comparison between PET and MR images. Despite the fact that the amount of F-l8-FDG applied to the patient was markedly reduced, the combination of 3D data acquisition and iterative image reconstruction resulted in excellent quality of the emission scans. By superpositioning of iteratively reconstructed emission and transmission scans, anatomical localization of breast lesions visualized on the emission scans could be improved. The postprocessing of the PET data described was completed in 60 min, this meaning that the presented concept can readily be employed in clinical practice.

32nd International Austrian Winter Symposium : Zell am See, the Netherlands. 20-23 January 2016

A1 68Ga-PSMA PET/CT in staging and restaging of Prostate Cancer Patients: comparative study with 18F-Choline PET/CT

W Langsteger, A Rezaee, W Loidl, HS Geinitz, F Fitz, M Steinmair, G Broinger, L Pallwien-Prettner, M Beheshti

A2 F18 Choline PET – CT: an accurate diagnostic tool for the detection of parathyroid adenoma?

L Imamovic, M Beheshti, G Rendl, D Hackl, O Tsybrovsky, M Steinmair, K Emmanuel, F Moinfar, C Pirich, W Langsteger

A3 [18F]Fluoro-DOPA-PET/CT in the primary diagnosis of medullary thyroid carcinoma

A Bytyqi, G Karanikas, M Mayerhöfer, O Koperek, B Niederle, M Hartenbach

A4 Variations of clinical PET/MR operations: An international survey on the clinical utilization of PET/MRI

T Beyer, K Herrmann, J Czernin

A5 Standard Dixon-based attenuation correction in combined PET/MRI: Reproducibility and the possibility of Lean body mass estimation

I Rausch, P Rust, MD DiFranco, M Lassen, A Stadlbauer, ME Mayerhöfer, M Hartenbach, M Hacker, T Beyer

A6 High resolution digital FDG PET/MRI imaging for assessment of ACL graft viability

K Binzel, R Magnussen, W Wei, MU Knopp, DC Flanigan, C Kaeding, MV Knopp

A7 Using pre-existing hematotoxicity as predictor for severe side effects and number of treatment cycles of Xofigo therapy

A Leisser, M Nejabat, M Hartenbach, G Kramer, M Krainer, M Hacker, A Haug

A8 QDOSE – comprehensive software solution for internal dose assessment

Wencke Lehnert, Karl Schmidt, Sharok Kimiaei, Marcus Bronzel, Andreas Kluge

A9 Clinical impact of Time-of-Flight on next-generation digital PET imaging of Yttrium-90 radioactivity following liver radioembolization

CL Wright, K Binzel, J Zhang, Evan Wuthrick, Piotr Maniawski, MV Knopp

A10 Snakes in patients! Lessons learned from programming active contours for automated organ segmentation

M Blaickner, E Rados, A Huber, M Dulovits, H Kulkarni, S Wiessalla, C Schuchardt, RP Baum, B Knäusl, D Georg

A11 Influence of a genetic polymorphism on brain uptake of the dual ABCB1/ABCG2 substrate [11C]tariquidar

M Bauer, B Wulkersdorfer, W Wadsak, C Philippe, H Haslacher, M Zeitlinger, O Langer

A12 Outcome prediction of temporal lobe epilepsy surgery from P-glycoprotein activity. Pooled analysis of (R)-[11C]-verapamil PET data from two European centres

M Bauer, M Feldmann, R Karch, W Wadsak, M Zeitlinger, MJ Koepp, M-C Asselin, E Pataraia, O Langer

A13 In-vitro and in-vivo characterization of [18F]FE@SNAP and derivatives for the visualization of the melanin concentrating hormone receptor 1

M Zeilinger, C Philippe, M Dumanic, F Pichler, J Pilz, M Hacker, W Wadsak, M Mitterhauser

A14 Reducing time in quality control leads to higher specific radioactivity of short-lived radiotracers

L Nics, B Steiner, M Hacker, M Mitterhauser, W Wadsak

A15 In vitro 11C-erlotinib binding experiments in cancer cell lines with epidermal growth factor receptor mutations

A Traxl, Thomas Wanek, Kushtrim Kryeziu, Severin Mairinger, Johann Stanek, Walter Berger, Claudia Kuntner, Oliver Langer

A16 7-[11C]methyl-6-bromopurine, a PET tracer to measure brain Mrp1 function: radiosynthesis and first PET evaluation in mice

S Mairinger, T Wanek, A Traxl, M Krohn, J Stanek, T Filip, M Sauberer, C Kuntner, J Pahnke, O Langer

A17 18F labeled azidoglucose derivatives as “click” agents for pretargeted PET imaging

D Svatunek, C Denk, M Wilkovitsch, T Wanek, T Filip, C Kuntner-Hannes, J Fröhlich, H Mikula

A18 Bioorthogonal tools for PET imaging: development of radiolabeled 1,2,4,5-Tetrazines

C Denk, D Svatunek, T Wanek, S Mairinger, J Stanek, T Filip, J Fröhlich, H Mikula, C Kuntner-Hannes

A19 Preclinical evaluation of [18F]FE@SUPPY- a new PET-tracer for oncology

T Balber, J Singer, J Fazekas, C Rami-Mark, N Berroterán-Infante, E Jensen-Jarolim, W Wadsak, M Hacker, H Viernstein, M Mitterhauser

A20 Investigation of Small [18F]-Fluoroalkylazides for Rapid Radiolabeling and In Vivo Click Chemistry

C Denk, D Svatunek, B Sohr, H Mikula, J Fröhlich, T Wanek, C Kuntner-Hannes, T Filip

A21 Microfluidic 68Ga-radiolabeling of PSMA-HBED-CC using a flow-through reactor

S Pfaff, C Philippe, M Mitterhauser, M Hartenbach, M Hacker, W Wadsak

A22 Influence of 24-nor-ursodeoxycholic acid on hepatic disposition of [18F]ciprofloxacin measured with positron emission tomography

T Wanek, E Halilbasic, M Visentin, S Mairinger, B Stieger, C Kuntner, M Trauner, O Langer

A23 Automated 18F-flumazenil production using chemically resistant disposable cassettes

P Lam, M Aistleitner, R Eichinger, C Artner

A24 Similarities and differences in the synthesis and quality control of 177Lu-DOTA-TATE, 177Lu -HA-DOTA-TATE and 177Lu-DOTA-PSMA (PSMA-617)

H Eidherr, C Vraka, A Haug, M Mitterhauser, L Nics, M Hartenbach, M Hacker, W Wadsak

A25 68Ga- and 177Lu-labelling of PSMA-617

H Kvaternik, R Müller, D Hausberger, C Zink, RM Aigner

A26 Radiolabelling of liposomes with 67Ga and biodistribution studies after administration by an aerosol inhalation system

U Cossío, M Asensio, A Montes, S Akhtar, Y te Welscher, R van Nostrum, V Gómez-Vallejo, J Llop

A27 Fully automated quantification of DaTscan SPECT: Integration of age and gender differences

F VandeVyver, T Barclay, N Lippens, M Troch

A28 Lesion-to-background ratio in co-registered 18F-FET PET/MR imaging – is it a valuable tool to differentiate between low grade and high grade brain tumor?

L Hehenwarter, B Egger, J Holzmannhofer, M Rodrigues-Radischat, C Pirich

A29 [11C]-methionine PET in gliomas - a retrospective data analysis of 166 patients

N Pötsch, I Rausch, D Wilhelm, M Weber, J Furtner, G Karanikas, A Wöhrer, M Mitterhauser, M Hacker, T Traub-Weidinger

A30 18F-Fluorocholine versus 18F-Fluorodeoxyglucose for PET/CT imaging in patients with relapsed or progressive multiple myeloma: a pilot study

T Cassou-Mounat, S Balogova, V Nataf, M Calzada, V Huchet, K Kerrou, J-Y Devaux, M Mohty, L Garderet, J-N Talbot

A31 Prognostic benefit of additional SPECT/CT in sentinel lymph node mapping of breast cancer patients

S Stanzel, G Pregartner, T Schwarz, V Bjelic-Radisic, B Liegl-Atzwanger, R Aigner

A32 Evaluation of diagnostic value of TOF-18F-FDG PET/CT in patients with suspected pancreatic cancer

S Stanzel, F Quehenberger, RM Aigner

A33 New quantification method for diagnosis of primary hyperpatahyroidism lesions and differential diagnosis vs thyropid nodular disease in dynamic scintigraphy

A Koljević Marković, Milica Janković, V Miler Jerković, M Paskaš, G Pupić, R Džodić, D Popović

A34 A rare case of diffuse pancreatic involvement in patient with merkel cell carcinoma detected by 18F-FDG

MC Fornito, D Familiari

A35 TSH-stimulated 18F-FDG PET/CT in the diagnosis of recurrent/metastatic radioiodine-negative differentiated thyroid carcinomas in patients with various thyroglobuline levels

P Koranda, H Polzerová, I Metelková, L Henzlová, R Formánek, E Buriánková, M Kamínek

A36 Breast Dose from lactation following I131 treatment

WH Thomson, C Lewis

A37 A new concept for performing SeHCAT studies with the gamma camera

WH Thomson, J O’Brien, G James, A Notghi

A38 Whole body F-18-FDG-PET and tuberculosis: sensitivity compared to x-ray-CT

H Huber, I Stelzmüller, R Wunn, M Mandl, F Fellner, B Lamprecht, M Gabriel

A39 Emerging role 18F-FDG PET-CT in the diagnosis and follow-up of the infection in heartware ventricular assist system (HVAD)

MC Fornito, G Leonardi

A40 Validation of Poisson resampling software

WH Thomson, J O’Brien, G James

A41 Protection of PET nuclear medicine personnel: problems in satisfying dose limit requirements

J Hudzietzová, J Sabol, M Fülöp

Basal Ganglia Iron in Patients with Multiple Sclerosis Measured with 7T Quantitative Susceptibility Mapping Correlates with Inhibitory Control

BACKGROUND AND PURPOSE

T2 hypointensity in the basal ganglia of patients with MS has been associated with clinical progression and cognitive decline. Our objectives were the following: 1) to compare signal in T2WI, R2 (ie, 1/T2), and R2* (ie, 1/T2*) relaxation rates and quantitative susceptibility mapping; and 2) to investigate the associations among MR imaging, clinical scores, and cognitive measures of inhibitory control linked to basal ganglia functioning.

MATERIALS AND METHODS

Twenty-nine patients with MS underwent a battery of neuropsychological tests including the Flanker and Stroop tasks. 7T MR imaging included 3D gradient-echo and single-echo multishot spin-echo EPI. Quantitative susceptibility mapping images were calculated by using a Wiener filter deconvolution algorithm. T2WI signal was normalized to CSF. R2 and R2* were calculated by log-linear regression. Average MR imaging metrics for the globus pallidus, putamen, and caudate were computed from manually traced ROIs including the largest central part of each structure.

RESULTS

Marked spatial variation was consistently visualized on quantitative susceptibility mapping and T2/T2*WI within each basal ganglia structure. MR imaging metrics correlated with each other for each basal ganglia structure individually. Notably, caudate and putamen quantitative susceptibility mapping metrics were similar, but the putamen R2 was larger than the caudate R2. This finding suggests that tissue features contribute differently to R2 and quantitative susceptibility mapping. Caudate and anterior putamen quantitative susceptibility mapping correlated with the Flanker but not Stroop measures; R2 did not correlate with inhibitory control measures. Putamen quantitative susceptibility mapping and caudate and putamen R2 correlated with the Expanded Disability Status Scale.

CONCLUSIONS

Our study showed that quantitative susceptibility mapping and R2 may be complementary indicators for basal ganglia tissue changes in MS. Our findings are consistent with the hypothesis that decreased performance of basal ganglia-reliant tasks involving inhibitory control is associated with increased quantitative susceptibility mapping.

A phase II and pharmacodynamic study of sunitinib in relapsed/refractory oesophageal and gastro-oesophageal cancers

BACKGROUND

Blockade of the vascular endothelial growth factor (VEGF) pathway shows evidence of activity in gastro-oesophageal (GE) and oesophageal cancer. We investigated the efficacy of sunitinib, a multikinase VEGF inhibitor, in patients with relapsed/refractory GE/oesophageal cancer.

METHODS

This was a single-stage Fleming phase II study. The primary end point was progression-free survival (PFS) at 24 weeks. If five or more patients out of a total of 25 were free of progressive disease at 24 weeks, sunitinib would be recommended for further study. Patients received sunitinib 37.5 mg orally daily and imaged every 6 weeks. Exploratory correlative analysis included serum growth factors, tumour gene expression and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

RESULTS

Twenty-five evaluable patients participated in the study. Progression-free survival at 24 weeks was 8% (n=2 patients; confidence interval (CI): 95% 1.4-22.5%), and the duration of best response for the patients was 23 and 72 weeks. Ten patients (42%) had stable disease (SD) for >10 weeks. Overall response rate is 13%. Median PFS is 7 weeks (95% CI: 5.6-11.4 weeks) and the median overall survival is 17 weeks (95% CI: 8.9-25.3 weeks). Most common grade 3/4 toxicities included fatigue (24%), anaemia (20%) thrombocytopenia (16%), and leucopenia (16%). No patients discontinued therapy due to toxicity. Serum VEGF-A and -C levels, tumour complement factor B (CFB) gene expression, and DCE-MRI correlated with clinical benefit, defined as SD or better as best response.

CONCLUSION

Sunitinib is well tolerated but only a select subgroup of patients benefited. Serum VEGF-A and -C may be early predictors of benefit. On this study, patients with clinical benefit from sunitinib had higher tumour CFB expression, and thus has identified CFB as a potential predictor for efficacy of anti-angiogenic therapy. These findings need validation from future prospective trials.

Quantitative assessment of the equine hoof using digital radiography and magnetic resonance imaging

REASONS FOR PERFORMING STUDY

Evaluation of laminitis cases relies on radiographic measurements of the equine foot. Reference values have not been established for all layers of the foot.

OBJECTIVES

To establish normal hoof wall and sole measurements using digital radiography (DR) and magnetic resonance imaging (MRI) and to document tissue components present in the dorsal hoof wall and solar layers seen on DR.

STUDY DESIGN

Prospective observational case-control study.

METHODS

Digital radiography and MRI were performed on 50 cadaver front feet from 25 horses subjected to euthanasia for nonlameness-related reasons. Four observers measured hoof wall (dorsal, lateral and medial) and sole thickness (sagittal, lateral and medial) using DR and magnetic resonance images. One observer repeated the measurements 3 times. Inter- and intraobserver correlation was assessed.

RESULTS

Digital radiography and MRI measurements for the normal hoof wall and sole were established. Inter- and intraobserver pairwise Pearson's correlation for DR (r>0.98) and MRI measurements (r>0.99) was excellent. Based on MRI, the less radiopaque layer on DR is comprised of the stratum lamellatum and stratum reticulare.

CONCLUSIONS

Normal DR and MRI measurements for the hoof wall and sole were established. On DR images, the less radiopaque layer of the foot observed corresponds to the critical tissues injured in laminitis, the strata lamellatum and reticulare. These reference measurements may be used by the clinician to detect soft-tissue changes in the laminitic equine foot and provide a foundation for future research determining changes in these measurements in horses with laminitis.

Direct delayed human adenoviral BMP-2 or BMP-6 gene therapy for bone and cartilage regeneration in a pony osteochondral model

OBJECTIVE

To evaluate healing of surgically created large osteochondral defects in a weight-bearing femoral condyle in response to delayed percutaneous direct injection of adenoviral (Ad) vectors containing coding regions for either human bone morphogenetic proteins 2 (BMP-2) or -6.

METHODS

Four 13mm diameter and 7mm depth circular osteochondral defects were drilled, 1/femoral condyle (n=20 defects in five ponies). At 2 weeks, Ad-BMP-2, Ad-BMP-6, Ad-green fluorescent protein (GFP), or saline was percutaneously injected into the central drill hole of the defect. Quantitative magnetic resonance imaging (qMRI) and computed tomography (CT) were serially performed at 12, 24, and 52 weeks. At 12 (one pony) or 52 weeks, histomorphometry and microtomographic analyses were performed to assess subchondral bone and cartilage repair tissue quality.

RESULTS

Direct delivery of Ad-BMP-6 demonstrated delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) and histologic evidence of greater Glycosaminoglycan (GAG) content in repair tissue at 12 weeks, while Ad-BMP-2 had greater non-mineral cartilage at the surface at 52 weeks (p<0.04). Ad-BMP-2 demonstrated greater CT subchondral bone mineral density (BMD) by 12 weeks and both Ad-BMP-2 and -6 had greater subchondral BMD at 52 weeks (p<0.05). Despite earlier (Ad-BMP-6) and more persistent (Ad-BMP-2) chondral tissue and greater subchondral bone density (Ad-BMP-2 and -6), the tissue within the large weight-bearing defects at 52 weeks was suboptimal in all groups due to poor quality repair cartilage, central fibrocartilage retention, and central bone cavitation. Delivery of either BMP by this method had greater frequency of subchondral bone cystic formation (p<0.05).

CONCLUSIONS

Delivery of Ad-BMP-2 or Ad-BMP-6 via direct injection supported cartilage and subchondral bone regeneration but was insufficient to provide long-term quality osteochondral repair.

Comparison of diagnostic quality and accuracy in color-coded versus gray-scale DCE-MR imaging display

PURPOSE

The purpose of this study was to evaluate the diagnostic value and tumor-vascular display properties (microcirculation) of two different functional MRI post-processing and display (color and gray-scale display) techniques used in oncology.

MATERIALS AND METHODS

The study protocol was approved by the IRB and written informed consent was obtained from all patients. 38 dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) data sets of patients with malignant pleural-mesothelioma were acquired and post-processed. DCE-MRI was performed at 1.5 tesla with a T1-weighted 2D gradient-echo-sequence (TR 7.0 ms, TE 3.9 ms, 15 axial slices, 22 sequential repetitions), prior and during chemotherapy. Subtracting first image of contrast-enhanced-dynamic series from the last, produced gray-scale images. Color images were produced using a pharmacokinetic two-compartment model. Eight raters, blinded to diagnosis, by visual assessment of post-processed images evaluated both diagnostic quality of the images and vasculature of the tumor using a rating scale ranging from -5 to +5. The scores for vasculature were assessed by correlating with the maximum amplitude of the total-tumor-ROI for accuracy.

RESULTS

Color coded images were rated as significantly higher in diagnostic quality and tumor vascular score than gray-scale images (p < 0.001, 0.005). ROI signal amplitude analysis and vascular ratings on color coded images were better correlated compared to gray-scale images rating (p < 0.05).

CONCLUSION

Color coded images were shown to have higher diagnostic quality and accuracy with respect to tumor vasculature in DCE-MRI, therefore their implementation in clinical assessment and follow-up should be considered for wider application.

Image fusion using CT, MRI and PET for treatment planning, navigation and follow up in percutaneous RFA

AIM

To evaluate the feasibility of fusion of morphologic and functional imaging modalities to facilitate treatment planning, probe placement, probe re-positioning, and early detection of residual disease following radiofrequency ablation (RFA) of cancer.

METHODS

Multi-modality datasets were separately acquired that included functional (FDG-PET and DCE-MRI) and standard morphologic studies (CT and MRI). Different combinations of imaging modalities were registered and fused prior to, during, and following percutaneous image-guided tumor ablation with radiofrequency. Different algorithms and visualization tools were evaluated for both intra-modality and inter-modality image registration using the software MIPAV (Medical Image Processing, Analysis and Visualization). Semi-automated and automated registration algorithms were used on a standard PC workstation: 1) landmark-based least-squares rigid registration, 2) landmark-based thin-plate spline elastic registration, and 3) automatic voxel-similarity, affine registration.

RESULTS

Intra- and inter-modality image fusion were successfully performed prior to, during and after RFA procedures. Fusion of morphologic and functional images provided a useful view of the spatial relationship of lesion structure and functional significance. Fused axial images and segmented three-dimensional surface models were used for treatment planning and post-RFA evaluation, to assess potential for optimizing needle placement during procedures.

CONCLUSION

Fusion of morphologic and functional images is feasible before, during and after radiofrequency ablation of tumors in abdominal organs. For routine use, the semi-automated registration algorithms may be most practical. Image fusion may facilitate interventional procedures like RFA and should be further evaluated.

Dose comparison of single- vs. double-dose in contrast-enhanced magnetic resonance angiography of the carotid arteries: Intraindividual cross-over blinded trial using Gd-DTPA

PURPOSE

To compare the intraindividual differences of single-dose (D(S)) and double-dose (D(D)) gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced magnetic resonance angiography (MRA) in the carotid arterial territory, an open-label single-center trial with blinded evaluations by two independent radiologists was undertaken.

MATERIALS AND METHODS

A total of 11 healthy volunteers were included in the study. Carotid MRAs were carried out in a 1.5 T clinical scanner using a neurovascular phased-array coil. Images were acquired with three-dimensional (3D) fast spoiled gradient recalled echo (FSPGR) sequence. Contrast agent was injected with a power injector, keeping the injection time constant for D(S) and D(D).

RESULTS

Both readers found at least 97% of vascular segments evaluable. Median overall image quality and diagnostic confidence were rated excellent and confident to very confident. No statistically significant difference between the dosage groups could be demonstrated. Variability based on a region of interest (ROI) signal intensity (SI) measurement was 7% for the D(S) and 5% for the D(D) group. SI, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were significantly higher for the D(D) group.

CONCLUSION

Our results demonstrate that while a double dosing of contrast agent does increase SNR, it does not lead to further improvement in visual and perceptual image quality. A single dosage of approximately 0.1 mmol/kg body weight (bw) Gd-DTPA may be the preferable dosage in the carotid arteries.

The assessment of antiangiogenic and antivascular therapies in early-stage clinical trials using magnetic resonance imaging: issues and recommendations

Vascular and angiogenic processes provide an important target for novel cancer therapeutics. Dynamic contrast-enhanced magnetic resonance imaging is being used increasingly to noninvasively monitor the action of these therapeutics in early-stage clinical trials. This publication reports the outcome of a workshop that considered the methodology and design of magnetic resonance studies, recommending how this new tool might best be used.

Benign prostate hyperplasia: evaluation of treatment response with DCE MRI

Benign prostate hyperplasia (BPH) is a major disease and its non-surgical therapy a major area of interest. The purpose of this study was to establish perfusion parameters in beagles with BPH using dynamic contrast-enhanced (DCE) MRI and to investigate changes due to the effects of finasteride treatment. Twelve male beagles (mean age 4.4 +/- 0.9,years) were divided into a control and treatment group that received a daily dose of 1 mg/kg finasteride. DCE MRI was carried out in a clinical scanner using a 3D spoiled gradient echo sequence prior to and during treatment. 0.2 mmol/kg contrast agent (gadoteridol) was administered with an injection rate of 0.2 ml/s followed by a 15 ml flush of saline. Contrast enhancement was evaluated by pharmacokinetic mapping of a two-compartment model with colour overlay images in addition to regional ROI analysis. Quantitative parameters were defined by the amplitude of contrast enhancement A, the exchange rate k(ep) and the time to maximum signal enhancement. Dynamic contrast-enhanced MRI investigations of the prostate revealed two distinct zones, an inner, periurethral zone and an outer, parenchymal zone. The periurethral zone is highly vascularized, whereas the parenchymal zone is moderately vascularized when compared to other parenchymal organs. During treatment, in the parenchymal zone the intensity of enhancement (amplitude A) and the time to maximum signal enhancement increased, while the exchange rate k(ep) decreased. Dynamic contrast-enhanced MRI of BPH reveals distinct differences between individual zones within the prostate. Moreover, changes during successful treatment suggest increased blood volume per volume of tissue and decreased vessel leakiness.

A comparison of Gd-BOPTA and Gd-DOTA for contrast-enhanced MRI of intracranial tumours

A two-centre intra-individual crossover study was performed in 23 patients with suspected high-grade glioma or metastases to assess and compare the safety and enhancement characteristics of two different MRI contrast media (gadobenate dimeglumine, Gd-BOPTA and gadoterate meglumine, Gd-DOTA) at equivalent doses of 0.1 mmol/kg body weight. T1-weighted spin-echo (SE) and T2-weighted fast SE images were obtained before and T1-weighted images 0, 2, 4, 6, 8 and 15 min after injection. T1-weighted images with magnetisation transfer contrast were acquired 12 min after injection. Qualitative assessment by blinded, off-site readers (reader 1:19 patients; reader 2:21) and on-site investigators (23) revealed significant (P< or =0.005) overall preference for Gd-BOPTA over Gd-DOTA for contrast enhancement (Gd-BOPTA preferred in 18, 15 and 18 cases; Gd-DOTA in 0, 1 and 1 and no preference in 1, 5 and 4; off-site readers 1 and 2, and on-site investigators, respectively). A similar significant preference for Gd-BOPTA was expressed by off-site readers and on-site investigators for lesion-to-brain contrast, lesion delineation, internal lesion structure, and overall image preference. Quantitative assessment by off-site readers revealed significantly (p<0.05) greater lesion enhancement with Gd-BOPTA than with Gd-DOTA at all times from 2 min after injection.

Klinische MRT bei 3�Tesla: Aktueller Stand

Clinical MRI is mostly performed at field strengths up to 1.5 Tesla (T). Recently, approved clinical whole-body MR-systems with a field strength of 3 T became available. Its installation base is more rapidly growing than anticipated. While site requirements and operation of these systems do not differ substantially from systems with lower field strength, there are differences in practical applications. Imaging applications can use the gain in signal-to-noise for increased spatial resolution or gain in speed. This comes at a trade off in increased sensitivity to field inhomogeneities and changes in relaxation times, which lead to changes in image contrast. The benefit of high field for spectroscopy consists in increased signal-to-noise-ratio and improvement in frequency resolution. The increase in energy deposition necessitates the use of special strategies to reduce the specific absorption rate (SAR). This paper summarizes the current state of MR at 3 T.

Klinische Hoch- und Ultrahochfeld-MR und ihre Wechselwirkung mit biologischen Systemen

The field strength of the static field in MRI has increased from 0.015 to 12 Tesla (T) during the last 25 years, which is about an 800 fold increase. In addition to low- and high field systems (1.5-4 T), ultra-high field systems with field strengths above 4 T are now available for human MRI. The extension of non-significant risk status for clinical fields up to 8 T by the FDA in July 2003 facilitates the further growth of this technology. The increase in field strength creates the need for a better understanding of the safety challenges to ensure safety for human imaging applications. This encompasses understanding the effects of the strong magnetic field at the atomic and molecular level and from biological tissue to organ systems. Moreover, in addition to the effects of a static magnetic field, the effects of radio-frequency- and gradient-fields have to be considered. This paper reviews the safety relevant issues for high- and ultrahigh field MR.

Dynamische Magnetresonanztomographie (dMRT)

PURPOSE

With the help of dynamic magnetic resonance tomography (dMRT) the status of tissue microcirculation can be visualized.

METHODS

Dynamic MRI was performed in 13 patients with advanced, nonresectable oro- or hypopharynx carcinoma at the beginning and the end of therapy. Maximal signal intensity and exchange rate constant in the tissue of the tumor and the lymph node metastases were analyzed using a pharmacokinetic two-compartment model.

RESULTS

In all six patients with clinical complete response (CR), the maximal signal intensity increased after therapy in the tissue of the primary tumor and the lymph node metastases. Furthermore, a high decrease in the parameter k(21) was associated with a better prognosis and could be observed especially after combined radiochemotherapy.

CONCLUSION

Our first results indicate that contrast-enhanced dynamic MRI studies before and after radio- or combined radiochemotherapy offer important information about the changes of microcirculation in the tissue of the tumor and lymph node metastases. Furthermore, this information seems to be a promising predictor for clinical outcome of therapy.

Assessment of brain metastases with dynamic susceptibility-weighted contrast-enhanced MR imaging: initial results

PURPOSE

To assess if preradiation and early follow-up regional cerebral blood volume (CBV) measurements can help predict treatment outcome in patients with cerebral metastases and to evaluate regional CBV changes in tumor and normal tissue after radiosurgery.

MATERIALS AND METHODS

In 18 patients, dynamic susceptibility-weighted contrast material-enhanced magnetic resonance (MR) imaging was performed with a 1.5-T unit, which allowed an absolute quantification of the regional CBV. Measurements were performed prior to and at 6 weeks and 3 months after therapy. Treatment outcome was classified according to tumor volume changes at 6 months. The regional CBV of the metastases and the normal adjacent brain tissue were determined with a region-of-interest analysis. Regional CBV values were correlated with the patient outcome to assess the sensitivity and specificity of dynamic susceptibility-weighted contrast-enhanced MR imaging.

RESULTS

The pretherapeutic regional CBV was not able to help predict a treatment outcome; however, the method proved to be highly sensitive and specific for treatment outcome prediction at the 6-week follow-up. A decrease of the regional CBV value helped predict the treatment outcome with a sensitivity of more than 90%. The tumor volume change alone had a sensitivity of only 64%. The measured regional CBV values of normal brain tissue and their ratio were comparable to physiologic data and remained unchanged with therapy.

CONCLUSION

The results suggest that dynamic susceptibility-weighted contrast-enhanced MR imaging is a useful method for the assessment of radiosurgically treated brain metastases. The implemented technique with determination of the arterial input function enables an absolute quantification of the regional CBV and prediction of tumor response.

[Multiphasic MR angiography as an intra-individual comparison between the contrast agents Gd-DTPA, Gd-BOPTA, and Gd-BT-DO3A]

QUESTION

The availability of new MR contrast agents having either a protein binding effect or higher concentration leads to the question if they differ from standard compounds in their vascular contrasting properties.

METHODS

By intraindividual comparison five volunteers were examined (1.5 T MR system) with a multi-phasic MRA of the abdomen each receiving three different contrast agents (gadopentetate dimeglumine 0.5 M; gadobenate dimeglumine 0.5 M, and gadobutrol 1.0 M). The dose (0.15 mmol/kg body weight) and flow rate (3.0 ml/s) were kept identical. All images were quantitatively and qualitatively evaluated by blinded assessment.

RESULTS

Significantly higher maximum signal intensity was found in the arteries for the protein interacting gadobenate dimeglumine (p = 0.05). No significant difference in vascular enhancement was demonstrated in the comparison of gadobutrol to gadopentetate dimeglumine.

CONCLUSION

Gadobenate dimeglumine was shown to be a favorable contrast agent for multi-phasic MRA. A higher concentrated Gd-chelate does not automatically lead to improved vascular contrast if standard imaging protocols are used.

Evaluation of neoadjuvant chemotherapeutic response of breast cancer using dynamic MRI with high temporal resolution

The aim of this study was to evaluate changes in both size and contrast enhancement of breast tumors during neoadjuvant chemotherapy, using dynamic MRI with high temporal resolution. Patients with advanced breast cancer (n=21) underwent a 1.5-T MRI scan prior to and following neoadjuvant chemotherapy with four cycles. Dynamic contrast enhancement was measured using a fast turbo-FLASH sequence and quantified using a two-compartment model with the parameters k(ep) and amplitude. Image analysis was done on images overlayed with a color map of parameters. The correlation between tumor diameter measured by histopathology and MRI was 0.7 (p<0.003). A reduction of tumor size after chemotherapy of more than 25% was associated with a decrease of both analyzed contrast enhancement parameters (k(ep): p<0.002; amplitude: p<0.006), where k(ep) began to drop already after the first cycle of chemotherapy (p<0.008). A clear reduction of tumor size was only noted after the third cycle (p<0.008). In patients without tumor regression there was also a trend towards an early reduction of contrast enhancement. We assume that MRI with high temporal resolution and color mapping is a novel tool to assess therapeutic effects of neoadjuvant chemotherapy in breast tumors, which deserves further prospective evaluation.

Cerebral arteriovenous malformations: morphologic evaluation by ultrashort 3D gadolinium-enhanced MR angiography

The purpose of this study was to evaluate the usefulness of a new ultrashort contrast-enhanced (CE) MR angiography (MRA) for the morphologic evaluation of cerebral arteriovenous malformations (AVMs). The method was compared with conventional X-ray digital subtraction angiography (DSA) and time-of-flight (TOF) MRA in 22 patients to assess the angioarchitecture of the malformations which is essential for treatment planning and follow-up. Two experienced MR readers independently evaluated both techniques with regard to the assessment of feeding arteries, AVM nidus, and venous drainage patterns. Contrast-enhanced MRA was able to detect all AVMs seen on DSA, whereas the TOF MRA failed in 1 patient with a very small AVM. In the assessment of the different vessel components of the AVM there was no difference for the detection and delineation of feeding arteries and the AVM. The venous drainage patterns could always be clearly delineated in the CE MRA, whereas TOF MRA could demonstrate the exact venous drainage in only 9 patients. Contrast-enhanced MRA was found to be superior to conventional TOF MRA in the assessment of the angioarchitecture of cerebral AVMs especially regarding the assessment of the venous drainage patterns. The superiority is supported by the improved vessel-to-background contrast and contrast-to-noise ratios. The major limitations of this new technique consist of a low spatial resolution at the used time resolution which can be improved by further sequence modifications. Contrast-enhanced MRA is thus an important additional imaging technique for treatment planning and follow-up of AVMs.

Assessment of gadobenate dimeglumine for magnetic resonance angiography: phase I studies

RATIONALE AND OBJECTIVES

To assess the vascular contrasting properties of a new MR contrast agent (gadobenate dimeglumine [Gd-BOPTA]), which presents higher relaxivity because of reversible, weak protein interaction, and, to compare these properties with a standard gadolinium agent.

MATERIALS AND METHODS

Two phase I trials compared intraindividually: (A) the vascular contrasting properties of Gd-BOPTA at three doses (0.0125, 0.05, and 0.2 mmol/kg body weight) and two flow rates (0.5 and 2.0 mL/s) in 10 volunteers; and (B) 0.1 mmol/kg body weight doses of Gd-BOPTA and Gd-DTPA at 2.0 mL/s using a modified magnetic resonance angiography (MRA) sequence with a temporal resolution of 1 s/f. Quantitative (ROI analysis) and fully blinded qualitative (reader review) assessment of images was performed.

RESULTS

A dose of 0.2 mmol/kg resulted in higher maximum intensities, longer median peak widths, and larger areas under the curve than did the lower doses (0.0125 mmol/kg and 0.05 mmol/kg). In the intraindividual comparison, Gd-BOPTA demonstrated significantly better vascular enhancement characteristics in terms of signal peak duration (p < 0.05), maximum signal intensity (p < 0.05), and area under the enhancement curve (p < 0.01). The multireader assessment for overall vascular contrast preferred Gd-BOPTA at p < 0.03.

CONCLUSIONS

Gd-BOPTA was shown to exhibit preferential and different vascular enhancement properties as compared with Gd-DTPA for MRA.

Comparison of pharmacokinetic MRI and [18F] fluorodeoxyglucose PET in the diagnosis of breast cancer: initial experience

It was the aim of this methodology-oriented clinical pilot study to compare the potential of dynamic MRI and 2-[18F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) for the detection and characterization of breast cancer. Fourteen women with suspicious breast lesions were examined. The MRI data were acquired with a turbo fast low-angle shot sequence and analyzed using a pharmacokinetic model. Emission data were detected in the sensitive 3D modus, iteratively reconstructed, and superimposed onto corresponding transmission images. In the 14 patients, 13 breast masses with a suspicious contrast enhancement and FDG uptake were detected. For these lesions, no statistically significant correlation between evaluated MR and PET parameters was found. Of the 9 histologically confirmed carcinomas, 8 were correctly characterized with MRI and PET. Two inflammatory lesions were concordantly classified as cancer. Moreover, dynamic MRI yielded another false-positive finding. In 6 patients, PET detected occult lymph node and/or distant metastases. Although both functional imaging techniques provide independent tissue information, the results concerning the diagnosis of primary breast lesions were almost identical. An advantage of PET, however, is its ability to localize lymph node involvement and distant metastases as an integral part of the examination.

Postoperative fluid-attenuated inversion recovery MR imaging of cerebral gliomas: initial results

Fluid-attenuated inversion-recovery (FLAIR) imaging has shown to be a valuable imaging modality in the assessment of intra-axial brain tumors; however, no data are available about the role of this technique in the clinically important postoperative stage. The purpose of this study was to evaluate the diagnostic potential of FLAIR MR imaging in residual tumor after surgical resection of cerebral gliomas. Fifteen patients with residual cerebral gliomas were examined within the first 18 days after partial surgical resection of cerebral gliomas. The imaging protocol included T1-weighted spin echo, T2- and proton-density-weighted fast spin echo, and FLAIR imaging with identical slice parameters. T1 and FLAIR were repeated after contrast media application. Detection and delineation of residual tumor were the primary parameters of the image analysis. Additionally, the influence of image artifacts on the image interpretation was assessed. On FLAIR images residual signal abnormalities at the border of the resection cavities were observed in all patients, whereas T2- and T1-weighted images present residual abnormalities in 13 of 15 and 10 of 15 patients, respectively. The FLAIR imaging was found to be superior to conventional imaging sequences in the delineation of these changes and comparable to contrast enhanced T1-weighted imaging in the delineation of residual enhancing lesions. Because of protein cell components and blood byproducts within the resection cavity, FLAIR imaging was unable to suppress the cerebrospinal fluid (CSF) in 4 patients. After the decomposition of proteins and blood, CSF could again be completely suppressed and residual or recurrent tumors were clearly identified. Our preliminary study has shown that FLAIR may be a valuable diagnostic modality in the early postoperative MR imaging after resection of cerebral gliomas due to its better delineation of residual pathologic signal at the border of the resection cavity. It should therefore be integrated into the early and/or intraoperative MR imaging protocol.

Dynamic susceptibility contrast-enhanced echo-planar imaging of cerebral gliomas. Effect of contrast medium extravasation

PURPOSE

To assess the influence of the degree of contrast medium extravasation on different DSC EPI MR sequences for perfusion MR imaging.

MATERIAL AND METHODS

60 patients with cerebral gliomas were examined by either an FID EPI or an SE EPI DSC MR sequence. The acquired images were evaluated on a qualitative and quantitative basis. For qualitative assessment, the homogeneity of the signal time curve, image artifacts, the degree of signal drop and the degree of enhancement were evaluated. The quantitative assessment included the percentage of signal drop and the contrast-to-noise ratio of the different EPI sequences was analyzed.

RESULTS

FID EPI presented a more homogeneous signal time curve and a more pronounced susceptibility effect than the SE EPI sequence. Due to the lesser susceptibility effect, the SE EPI sequence was not as sensitive to contrast media extravasation. The signal returned to baseline in all patients. In patients with strongly enhancing lesions, the FID EPI sequence suffered from considerable T1 effects, causing problems in the quantification of perfusion data.

CONCLUSION

FID EPI sequences were preferred for perfusion MR imaging in patients without strong enhancing lesions, e.g. in ischemia or tumors with intact blood-brain barrier. In patients with suspected strong enhancing lesions, an SE EPI sequence should be used.