MR-Guided Transurethral Ultrasound Ablation of Prostate Cancer: Initial Experience of Monitoring Tumor Response by Dynamic Apparent Diffusion Coefficient Measurements at 3.0 T.

INTRODUCTION: Diffusion-weighted imaging (DWI) as part of multiparametric magnetic resonance imaging (mpMRI) is an important sequence for the detection of prostate cancer (PCa). The objective of this retrospective analysis was to evaluate changes in apparent diffusion coefficient (ADC) measurements in biopsy-proven PCa undergoing TULSA-PRO (MR-guided transurethral ultrasound ablation of the prostate) at 3.0 T after 1, 3, and 6-12 months posttreatment. METHODS: Nineteen patients underwent follow-up examinations after 1, 3, and 6-12 months including mpMRI at 3.0 T and urological-clinical examinations with quantitative analysis of ADCs. RESULTS: In PCa, a significant increase of ADC values after 6-12 months was measured after TULSA-PRO treatment by 29.1% (pre-TULSA: 0.79 ± 0.16 × 10-3 mm2/s, 6-12 months: 1.02 ± 0.35 × 10-3 mm2/s), while the corresponding value in the reference tissue decreased by 48.5% (pre-TULSA: 1.20 ± 0.15 × 10-3 mm2/s, 6-12 months: 0.91 ± 0.29 × 10-3 mm2/s). The mean ADC values in the early follow-up groups at 1 and 3 months did not change significantly. CONCLUSION: DWI with ADC as part of mpMRI can serve as a biomarker to dynamically monitor the follow-up after TULSA after 6-12 months. For early posttreatment progression, it is not suitable due to too many confounding variables.

Antibody-mediated procoagulant platelets in SARS-CoV-2-vaccination associated immune thrombotic thrombocytopenia.

The COVID-19 pandemic has resulted in significant morbidity and mortality worldwide. To prevent severe infection, mass COVID-19 vaccination campaigns with several vaccine types are currently underway. We report pathological and immunological findings in 8 patients who developed vaccine-induced immune thrombotic thrombocytopenia (VITT) after administration of SARS-CoV-2 vaccine ChAdOx1 nCoV-19. We analyzed patient material using enzyme immune assays, flow cytometry and heparin-induced platelet aggregation assay and performed autopsies on two fatal cases. Eight patients (5 female, 3 male) with a median age of 41.5 years (range, 24 to 53) were referred to us with suspected thrombotic complications 6 to 20 days after ChAdOx1 nCoV-19 vaccination. All patients had thrombocytopenia at admission. Patients had a median platelet count of 46.5 x109/L (range, 8 to 92). Three had a fatal outcome and 5 were successfully treated. Autopsies showed arterial and venous thromboses in various organs and the occlusion of glomerular capillaries by hyaline thrombi. Sera from VITT patients contain high titer antibodies against platelet factor 4 (PF4) (OD 2.59±0.64). PF4 antibodies in VITT patients induced significant increase in procoagulant markers (P-selectin and phosphatidylserine externalization) compared to healthy volunteers and healthy vaccinated volunteers. The generation of procoagulant platelets was PF4 and heparin dependent. We demonstrate the contribution of antibody-mediated platelet activation in the pathogenesis of VITT.

Synovial inflammation analyzed by 3-T magnetic resonance imaging in etanercept-treated patients with rheumatoid arthritis indicates persistent disease activity despite of clinical remission: A pilot study.

OBJECTIVES: To evaluate joint inflammation using 3-T MRI in rheumatoid arthritis (RA) patients treated with conventional disease modifying anti-rheumatic drugs (cDMARDs) as compared to inhibitors for tumor necrosis factor α (TNFi) over 12 months. METHODS: Prospective epidemiologic clinical pilot study using the RA MRI system (RAMRIS), the visual analog scale (VAS, 0-100) and the Disease Activity Score 28-joint count (DAS28) at baseline, 4, and 12 months after initiation of etanercept (ETA). Ten patients with inadequate response to two cDMARDs were treated with ETA and compared to 10 patients responding to cDMARDs. RESULTS: In cDMARD patients, parameters at baseline and 12 months did not change: VAS: 21.0 ± 11.3 and 20.2 ± 24.6; DAS28: 2.1 ± 0.6 and 2.9 ± 1.0; and RAMRIS: 11.0 ± 2.3 and 11.8 ± 2.8, respectively. In contrast, in the ETA-patients the same parameters were as follows at baseline, 4, and 12 months: VAS: 46.3 ± 7.9, 23.9 ± 7.1, and 24.0 ± 6.3 (each p = .04); DAS28: 3.8 ± 0.4, 2.8 ± 0.3 (ns), and 2.5 ± 0.3 (p = .01); and RAMRIS: 28.9 ± 5.0, 25.8 ± 4.7 (ns), and 24.6 ± 4.5 (ns). Comparing ETA and cDMARD patients, RAMRIS was significantly different. CONCLUSION: The data suggest that synovial inflammation and DAS28 remission are separate entities in RA. MRI scoring before starting a treatment may therefore indicate the requirement for TNFi.

Revised PROPELLER for T2-weighted imaging of the prostate at 3 Tesla: impact on lesion detection and PI-RADS classification.

PURPOSE: To evaluate revised PROPELLER (RevPROP) for T2-weighted imaging (T2WI) of the prostate as a substitute for turbo spin echo (TSE). MATERIALS AND METHODS: Three-Tesla MR images of 50 patients with 55 cancer-suspicious lesions were prospectively evaluated. Findings were correlated with histopathology after MRI-guided biopsy. T2 RevPROP, T2 TSE, diffusion-weighted imaging, dynamic contrast enhancement, and MR-spectroscopy were acquired. RevPROP was compared to TSE concerning PI-RADS scores, lesion size, lesion signal-intensity, lesion contrast, artefacts, and image quality. RESULTS: There were 41 carcinomas in 55 cancer-suspicious lesions. RevPROP detected 41 of 41 carcinomas (100%) and 54 of 55 lesions (98.2%). TSE detected 39 of 41 carcinomas (95.1%) and 51 of 55 lesions (92.7%). RevPROP showed fewer artefacts and higher image quality (each p < 0.001). No differences were observed between single and overall PI-RADS scores based on RevPROP or TSE (p = 0.106 and p = 0.107). Lesion size was not different (p = 0.105). T2-signal intensity of lesions was higher and T2-contrast of lesions was lower on RevPROP (each p < 0.001). CONCLUSION: For prostate cancer detection RevPROP is superior to TSE with respect to motion robustness, image quality and detection rates of lesions. Therefore, RevPROP might be used as a substitute for T2WI. KEY POINTS: • Revised PROPELLER can be used as a substitute for T2-weighted prostate imaging. • Revised PROPELLER detected more carcinomas and more suspicious lesions than TSE. • Revised PROPELLER showed fewer artefacts and better image quality compared to TSE. • There were no significant differences in PI-RADS scores between revised PROPELLER and TSE. • The lower T2-contrast of revised PROPELLER did not impair its diagnostic quality.

Incidence and risk factors of early arterial blood flow stasis during first radioembolization of primary and secondary liver malignancy using resin microspheres: an initial single-center analysis.

OBJECTIVES: To retrospectively determine incidence of early arterial blood flow stasis and its influencing factors during resin-based radioembolization (RE) of liver tumours. METHODS: Data of patients undergoing resin-based RE from 06/2006-12/2013 were reviewed. Second RE procedures of the same liver lobe were excluded. 90-yttrium dose was calculated according to the body surface area method. Data were categorized according to RE without full dose application because of early stasis and with full dose application. Clinical/procedural characteristics were recorded. Logistic regression was performed to identify associations between clinical/procedural characteristics and early stasis. RESULTS: 362 patients [220 male; mean age 62 years (range 26-90)] underwent 416 RE sessions with early stasis occurring in 103 REs (24.8 %). Highest incidence and degree of stasis were observed in breast cancer metastases [42.6 % (20/47); 55.8 % of mean intended dose administered]. Independent risk factors were: metastasized breast cancer (odds ratio [OR] 2.18, p = 0.02), liver tumour-burden <25 % and 25-50 % (ORs 5.33, 15.64; p < 0.0001), tumour hypovascularity (OR 2.70, p = 0.04), previous bevacizumab therapy (OR 2.79, p = 0.0009) and concurrent chemotherapy (OR 8.69, p < 0.0001). CONCLUSION: Early stasis was observed in 24.8 % of resin-based REs. In the presence of the identified risk factors, extra care should be taken during microsphere administration. KEY POINTS: • Early arterial blood flow stasis is a known problem of resin-based RE. • The study showed that early stasis occurs in 25 % of REs. • Several clinical and procedural factors are associated with early stasis. • In patients at risk extra care should be taken during RE.

Yttrium-90 Radioembolization of Advanced, Unresectable Breast Cancer Liver Metastases-A Single-Center Experience.

PURPOSE: To determine value of transarterial radioembolization (TARE) for palliative treatment of unresectable liver-dominant breast metastases (LdBM) and to determine prognostic parameters. MATERIALS AND METHODS: Records of patients undergoing TARE for progressing LdBM between June 2006 and March 2015 were retrospectively reviewed; 44 female patients (mean age 56.1 y; range, 34.9-85.3 y) underwent 69 TAREs (56 resin-based, 13 glass-based). Of 44 patients, 42 had bilobar disease. Mean administered activity was 1.35 GBq ± 0.71. Median clinical and imaging follow-up times were 121 days (range, 26-870 d; n = 42 patients) and 93 days (range, 26-2,037 d; n = 38 patients). Clinical and biochemical toxicities, imaging response (according to Response Evaluation Criteria In Solid Tumors), time to progression, and overall survival (OS) were evaluated. Data were analyzed with stratification according to clinical and procedural parameters. RESULTS: Toxicities included 1 cholecystitis (grade 2) and 1 duodenal ulceration (grade 3); no grade ≥ 4 clinical toxicities were noted. Objective response rate (complete + partial response) was 28.9% (11/38); disease control rate (response + stable disease) was 71.1% (27/38). Median time to progression of treated liver lobe was 101 days (range, 30-2,037 d). During follow-up, 34/42 patients died (median OS after first TARE: 184 d [range 29-2,331 d]). On multivariate analysis, baseline Eastern Cooperative Oncology Group (ECOG) status of 0 (P < .0001, hazard ratio [HR] = 0.146) and low baseline γ-glutamyltransferase (GGT) levels (P = .0146, HR = 0.999) were predictors of longer OS. CONCLUSIONS: TARE can successfully delay progression of therapy-refractory LdBM with low complication rate. Nonelevated baseline ECOG status and low GGT levels were identified as prognostic factors.

Intravoxel Incoherent Motion Diffusion-Weighted MR Imaging for Prediction of Early Arterial Blood Flow Stasis in Radioembolization of Breast Cancer Liver Metastases.

PURPOSE: To retrospectively evaluate predictive value of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) for early arterial blood flow stasis during transarterial radioembolization (TARE) of liver dominant breast metastases (LdBM). MATERIALS AND METHODS: Preinterventional 1.5T DWI (b0, b1, b2 = 0, 50, 800 s/mm(2)) data for 28 liver lobes of 18 female patients treated by resin-based radioembolization (10 bilobar and 8 unilobar treatments) were analyzed. Apparent diffusion coefficient (ADC) (0, 800) and an estimation of the true diffusion coefficient D' and of the perfusion fraction f' were calculated for the 2 largest metastases. Response rate at 3 months and survival were analyzed. Procedures without full dose application because of early stasis were assigned to group A (n = 15), and procedures with full dose application were assigned to group B (n = 13). RESULTS: Metastases in group A showed significantly lower f' (0.035 ± 0.018 vs 0.076 ± 0.015, P < .0001) and a trend toward lower ADC(0, 800) with values given in 10(-6) mm(2)/s (1,066 ± 141 vs 1,189 ± 176, P = .051); no group difference was shown for D'. Groups were best discriminated by weighted mean f' values of the 2 largest metastases with accuracy of 100%. Mean tumor diameter before and after TARE was 51 mm ± 18 and 50 mm ± 24 in group A and 47 mm ± 27 and 48 mm ± 32 for group B. Imaging response did not differ between groups (P = .545). Overall survival did not differ significantly between group A (230 d) and B (155 d) (P = .124). CONCLUSIONS: Perfusion-sensitive IVIM parameter f' may predict early blood flow stasis in patients undergoing TARE for LdBM. Determination of this parameter before intervention may increase awareness of the interventionalist and increase safety of microsphere administration.

Safety of gadobutrol in more than 1,000 pediatric patients: subanalysis of the GARDIAN study, a global multicenter prospective non-interventional study.

BACKGROUND: Gadobutrol is a gadolinium-based contrast agent, uniquely formulated at 1.0 mmol/ml. Although there is extensive safety evidence on the use of gadobutrol in adults, few studies have addressed the safety and tolerability of gadobutrol in pediatric patients. OBJECTIVE: This subanalysis of data from the GARDIAN study evaluated the safety and use of gadobutrol in pediatric patients (age <18 years). MATERIALS AND METHODS: The GARDIAN study was a large phase IV non-interventional prospective multicenter post-authorization safety study performed in Europe, Asia, North America and Africa. A total of 23,708 patients were included who were scheduled to undergo cranial or spinal MRI, liver or kidney MRI, or MR angiography with gadobutrol enhancement. The primary study endpoint was the overall incidence of adverse drug reactions (ADRs) and serious adverse events (SAEs) following gadobutrol administration. RESULTS: The GARDIAN study included 1,142 children (age <18 years) who received gadobutrol at a mean dose of 0.13 (range 0.04-0.50) mmol/kg body weight. Gadobutrol was well tolerated in these children, with low rates of ADRs (0.5%) and no SAEs, consistent with results in adults enrolled in the GARDIAN study. Rates of adverse events and ADRs were unrelated to pediatric age or gadobutrol weight-adjusted dose. There were no symptoms suggestive of nephrogenic systemic fibrosis. Investigators rated the contrast quality of gadobutrol-enhanced images as good or excellent in 97.8% of pediatric patients, similar to the main study population. CONCLUSION: Gadobutrol is very well tolerated and provides excellent contrast quality at the recommended weight-adjusted dose in children (age <18 years), similar to the profile in adults.

A new robotic assistance system for percutaneous CT-guided punctures: Initial experience.

PURPOSE: To evaluate the feasibility of CT-guided bone biopsies using a novel robotic needle guide. MATERIAL AND METHODS: The robotic needle guide iSYS 1.3 (iSYS Medzintechnik, GmbH, Kitzbuehel, Austria) mounted on the standard table of a CT scanner was used for all studies. For preclinical testing, eight vertebral bodies of dead swine were biopsied, trying to place the needle in the center of the vertebral body via a transpedicular access. For clinical evaluation, bone biopsies were taken in three different patients with ambiguous bone lesions. All biopsies were performed under general anesthesia, using a 12G bone biopsy needle. RESULTS: The animal studies demonstrated that the biopsy needle could be placed accurately in the center of the vertebral body in all cases. No readjustment was necessary, the CT scans demonstrated an intrapedicular trajectory avoiding the spinal canal or the neural foramina. Subsequently, following the animal studies, all biopsies could be performed successfully. Needle placement was accurate without any need for readjustment. No complications occurred during the procedure. CONCLUSION: Using the iSYS 1.3 allows for accurate and simple stereotactic biopsies of bone lesions, avoiding the need for needle readjustment. The systems may offer even less experienced teams to take biopsies in regions which are difficult to access.

Respiratory motion artefacts in dynamic liver MRI: a comparison using gadoxetate disodium and gadobutrol.

OBJECTIVES: Our aim was to retrospectively evaluate the occurrence of respiratory motion artefacts in patients undergoing dynamic liver magnetic resonance (MR) either with gadoxetate disodium or gadobutrol. METHODS: Two hundred and thirty liver MR studies (115 with gadobutrol, 115 with gadoxetate disodium) were analysed. Respiratory motion artefacts on dynamic 3D T1-weighted MR images (pre-contrast, arterial, venous, and late-dynamic phase) were assessed using a five-point rating scale. Severe motion was defined as a score ≥ 4. Mean motion scores were compared with the Mann-Whitney-U-test. The chi-squared-test was used for dichotomous comparisons. RESULTS: Mean motion scores for gadoxetate disodium and gadobutrol showed no relevant differences for each phase of the dynamic contrast series (pre-contrast: 1.85 ± 0.70 vs. 1.88 ± 0.57, arterial: 1.85 ± 0.81 vs. 1.87 ± 0.74, venous: 1.82 ± 0.67 vs. 1.74 ± 0.64, late-dynamic: 1.75 ± 0.62 vs. 1.79 ± 0.63; p = 0.469, 0.557, 0.382 and 0.843, respectively). Severe motion artefacts had a similar incidence using gadoxetate disodium and gadobutrol (11/460 [2.4%] vs. 7/460 [1.5%]; p = 0.341). CONCLUSIONS: Gadoxetate disodium is associated with equivalent motion scores compared to gadobutrol in dynamic liver MRI. In addition, both contrast agents demonstrated a comparable and acceptable rate of severe respiratory motion artefacts. KEY POINTS: • Gadobutrol and gadoxetate disodium showed comparable motion scores in dynamic phase imaging. • The incidence of severe motion artefacts was pronounced in arterial phase imaging. • Adverse respiratory side effects were not recorded in 115 examinations with gadoxetate disodium.

Comparison between modified Dixon MRI techniques, MR spectroscopic relaxometry, and different histologic quantification methods in the assessment of hepatic steatosis.

OBJECTIVES: To compare systematically quantitative MRI, MR spectroscopy (MRS), and different histological methods for liver fat quantification in order to identify possible incongruities. METHODS: Fifty-nine consecutive patients with liver disorders were examined on a 3 T MRI system. Quantitative MRI was performed using a dual- and a six-echo variant of the modified Dixon (mDixon) sequence, calculating proton density fat fraction (PDFF) maps, in addition to single-voxel MRS. Histological fat quantification included estimation of the percentage of hepatocytes containing fat vesicles as well as semi-automatic quantification (qHisto) using tissue quantification software. RESULTS: In 33 of 59 patients, the hepatic fat fraction was >5% as determined by MRS (maximum 45%, mean 17%). Dual-echo mDixon yielded systematically lower PDFF values than six-echo mDixon (mean difference 1.0%; P < 0.001). Six-echo mDixon correlated excellently with MRS, qHisto, and the estimated percentage of hepatocytes containing fat vesicles (R = 0.984, 0.967, 0.941, respectively, all P < 0.001). Mean values obtained by the estimated percentage of hepatocytes containing fat were higher by a factor of 2.5 in comparison to qHisto. Six-echo mDixon and MRS showed the best agreement with values obtained by qHisto. CONCLUSIONS: Six-echo mDixon, MRS, and qHisto provide the most robust and congruent results and are therefore most appropriate for reliable quantification of liver fat. KEY POINTS: • Six-echo mDixon correlates excellently with MRS, qHisto, and the estimated percentage of fat-containing hepatocytes. • Six-echo mDixon, MRS, and qHisto provide the most robust and congruent results. • Dual-echo mDixon yields systematically lower PDFF values than six-echo mDixon. • The percentage of fat-containing hepatocytes is 2.5-fold higher than fat fraction determined by qHisto. • Performance characteristics and systematic differences of the various methods should be considered.

Outcome of peptide receptor radionuclide therapy with 177Lu-octreotate in advanced grade 1/2 pancreatic neuroendocrine tumours.

PURPOSE: The clinical benefit of peptide receptor radionuclide therapy (PRRT) in patients with pancreatic neuroendocrine tumours (pNET) has not yet been well described and defined in its full extent due to limited data in this tumour subgroup. This study was intended to obtain robust, comparative data on the outcome and toxicity of standardized PRRT with (177)Lu-octreotate in a well-characterized population of patients with advanced pNET of grade 1/2 (G1/2). METHODS: We retrospectively analysed a cohort of 68 pNET patients with inoperable metastatic disease consecutively treated with (177)Lu-octreotate (four intended cycles at 3-monthly intervals; mean activity per cycle 8.0 GBq). Of these 68 patients, 46 (67.6 %) had documented morphological tumour progression during the 12 months before initiation of treatment, and PRRT was the first-line systemic therapy in 35 patients (51.5 %). Response was evaluated according to modified Southwest Oncology Group (SWOG) criteria and additionally with Response Criteria in Solid Tumors (RECIST) 1.1. Survival was analysed using Kaplan-Meier curves and Cox proportional hazards model for univariate and multivariate analyses. Toxicity was assessed by standard follow-up laboratory work-up including blood count, and liver and renal function, supplemented with serial (99m)Tc-DTPA clearance measurements. RESULTS: The median follow-up period was 58 months (range 4 - 112). Reversible haematotoxicity (grade 3 or more) occurred in four patients (5.9 %). No significant nephrotoxicity (grade 3 or more) was observed. Treatment responses (SWOG criteria) consisted of a partial response in 41 patients (60.3 %), a minor response in 8 (11.8 %), stable disease in 9 (13.2 %), and progressive disease in 10 (14.7 %). Median progression-free survival (PFS) and overall survival (OS) were 34 (95 % CI 26 - 42) and 53 months (95 % CI 46 - 60), respectively. A G1 proliferation status was associated with longer PFS (p = 0.04) and OS (p = 0.044) in the multivariate analysis. Variables linked to impaired OS, on the other hand, were a reduced performance status (Karnofsky score ≤ 70 %, p = 0.007), a high hepatic tumour burden (≥ 25 % liver volume, p = 0.017), and an elevated plasma level of neuron-specific enolase (NSE >15 ng/ml, p = 0.035). CONCLUSION: The outstanding response rates and survival outcomes suggest that PRRT is highly effective in advanced G1/2 pNET when compared to data of other treatment modalities. Independent predictors of survival are the tumour proliferation index, the patient's performance status, tumour burden and baseline plasma NSE level.

Ultrafast volumetric B1 (+) mapping for improved radiofrequency shimming in 3 tesla body MRI.

PURPOSE: To evaluate the use of the recently proposed ultrafast B1 (+) mapping approach DREAM (Dual Refocusing Echo Acquisition Mode) for a refinement of patient adaptive radiofrequency (RF) shimming. MATERIALS AND METHODS: Volumetric DREAM B1 (+) calibration scans centered in the upper abdomen were acquired in 20 patients and three volunteers with written informed consent at a clinical dual source 3 Tesla (T) MR system. Based on these data, RF transmit settings were optimized by central-slice based RF-shimming (CS-RF shim) and by a refined, multi-slice adaptive approach (MS-RF shim). Simulations were performed to compare flip angle accuracy and B1 (+) homogeneity (cv = stddev/mean) achieved by CS-RF shim versus MS-RF shim for transversal and coronal slices, and for volume shimming on the spine. RESULTS: By MS-RF shim, mean deviation from nominal flip angle was reduced to less than 11% in all slices, all targets, and all subjects. Relative improvements in B1 (+) cv (MS-RF shim versus CS-RF) were up to 14%/39%/47% in transversal slices/coronal slices/ spine area. CONCLUSION: Volumetric information about B1 (+) can be used to further improve the accuracy and homogeneity of the B1 (+) field yielding higher diagnostic confidence, and will also be of value for various quantitative methods which are sensitive to flip angle imperfections.

0.125 mm(3) spatial resolution steady-state MR angiography of the thighs with a blood pool contrast agent using the quadrature body coil only at 1.5 Tesla.

PURPOSE: To implement and evaluate high spatial resolution three-dimensional MR contrast-enhanced angiography (3D-CEMRA) of the thighs using a blood pool contrast agent (BPCA) using the quadrature body coil only in patients with peripheral arterial occlusive disease (PAOD) in cases receiver coils cannot be used at 1.5 Tesla (T). MATERIALS AND METHODS: Nineteen patients (mean age: 68.7 ± 11.2 years; range, 38-83 years) with known PAOD (Fontaine stages; III: 16, IV: 3) prospectively underwent 3D-CEMRA at 1.5T with a noninterpolated voxel size of 0.49 × 0.49 × 0.48 mm(3) . Digital subtraction angiography (DSA) was available for comparison in all patients. Two readers independently evaluated movement artifacts, overall image quality of 3D-CEMRA, and grade of stenosis as compared to DSA. SNR and CNR levels were quantified. RESULTS: The 3D-CEMRA was successfully completed in all patients. Patient movement artifacts that affected stenosis grading occurred in 3/38 thighs. Overall image quality was rated excellent in 15/38, good in 12/38, and diagnostic in 8/38 thighs. Stenosis grading matched with that in DSA in 35/38 thighs. High SNR and CNR were measured in all vessels. CONCLUSION: The 0.125 mm(3) spatial resolution 3D-CEMRA of the thighs with a BPCA is feasible using a quadrature body coil exclusively with excellent image quality despite long acquisition times. J. Magn. Reson. Imaging 2014;40:996-1001. © 2014 Wiley Periodicals, Inc.

Diffusion-weighted imaging with acquisition of three b-values for response evaluation of neuroendocrine liver metastases undergoing selective internal radiotherapy.

OBJECTIVES: To evaluate diffusion-weighted MRI with acquisition of three b-values and calculation of fractioned ADCs for response evaluation of neuroendocrine liver metastases undergoing selective internal radiotherapy (SIRT). METHODS: Ten consecutive patients with neuroendocrine liver metastases underwent MRI before and following SIRT. Diffusion-weighted imaging included acquisition of the b-values 0, 50 and 800 s/mm(2) and calculation of ADC(50,800), ADC(0,50) and ADC(0,800) maps. According to therapy response, lesions were categorised into group A [≥20% reduction of the longest diameter (LD) in comparison to baseline MRI] and group B (<20% reduction of the LD). RESULTS: Twelve out of 31 metastases were categorised as group A and 19 out of 31 metastases were categorised as group B. Pretherapeutic values of ADC(0,800) and ADC(50,800) did not differ significantly between the two groups; however, ADC(0,50) was 32% lower in group A (P = 0.049). ADC(0,800) and ADC(50,800) increased significantly after therapy in both groups, however, group differences were not statistically significant. Conversely, the increase in ADC(0,50) was about a factor of 7 larger in group A than in group B (P = 0.023). CONCLUSIONS: Our study showed that the ADC(0,50) is a promising biomarker for response assessment of neuroendocrine liver metastases following SIRT. KEY POINTS: • Diffusion-weighted MRI offers new information about neuroendocrine hepatic metastases. • Evaluation of perfusion and diffusion components requires fractioned apparent diffusion coefficients (ADCs). • Perfusion effects represented by ADC (0.50) can be observed in neuroendocrine metastases. • Pretherapeutic ADC (0.50) was significantly lower in metastases with a response ≥20%. • Such biomarkers may help evaluate liver metastases in patients undergoing therapy.

Hepatobiliary magnetic resonance imaging in patients with liver disease: correlation of liver enhancement with biochemical liver function tests.

OBJECTIVES: To evaluate hepatobiliary magnetic resonance imaging (MRI) using Gd-EOB-DTPA in relation to various liver function tests in patients with liver disorders. METHODS: Fifty-one patients with liver disease underwent Gd-EOB-DTPA-enhanced liver MRI. Based on region-of-interest (ROI) analysis, liver signal intensity was calculated using the spleen as reference tissue. Liver-spleen contrast ratio (LSCR) and relative liver enhancement (RLE) were calculated. Serum levels of total bilirubin, gamma glutamyl transpeptidase (GGT), aspartate aminotransferase (AST), alanine aminotransferase (ALT), glutamate dehydrogenase (GLDH), lactate dehydrogenase (LDH), serum albumin level (AL), prothrombin time (PT), creatinine (CR) as well as international normalised ratio (INR) and model for end-stage liver disease (MELD) score were tested for correlation with LSCR and RLE. RESULTS: Pre-contrast LSCR values correlated with total bilirubin (r = -0.39; p = 0.005), GGT (r = -0.37; p = 0.009), AST (r = -0.38; p = 0.013), ALT (r = -0.29; p = 0.046), PT (r = 0.52; p < 0.001), GLDH (r = -0.55; p = 0.044), INR (r = -0.42; p = 0.003), and MELD Score (r = -0.53; p < 0.001). After administration of Gd-EOB-DTPA bilirubin (r = -0.45; p = 0.001), GGT (r = -0.40; p = 0.004), PT (r = 0.54; p < 0.001), AST (r = -0.46; p = 0.002), ALT (r = -0.31; p = 0.030), INR (r = -0.45; p = 0.001) and MELD Score (r = -0.56; p < 0.001) significantly correlated with LSCR. RLE correlated with bilirubin (r = -0.40; p = 0.004), AST (r = -0.38; p = 0.013), PT (r = 0.42; p = 0.003), GGT (r = -0.33; p = 0.020), INR (r = -0.36; p = 0.011) and MELD Score (r = -0.43; p = 0.003). CONCLUSIONS: Liver-spleen contrast ratio and relative liver enhancement using Gd-EOB-DTPA correlate with a number of routinely used biochemical liver function tests, suggesting that hepatobiliary MRI may serve as a valuable biomarker for liver function. The strongest correlation with liver enhancement was found for the MELD Score. KEY POINTS: • Relative enhancement (RLE) of Gd-EOB-DTPA is related to biochemical liver function tests. • Correlation of RLE with bilirubin, ALT, AST, GGT, INR and MELD Score is reverse. • The correlation of relative liver enhancement with prothrombin time is positive. • AST, ALT, GLDH, prothrombin time, INR and MELD Score correlate with pre-contrast liver-spleen contrast ratio. • Such biomarkers may help to evaluate liver function.

Dynamic and simultaneous MR measurement of R1 and R2* changes during respiratory challenges for the assessment of blood and tissue oxygenation.

This work presents a novel method for the rapid and simultaneous measurement of R1 and R2* relaxation rates. It is based on a dynamic short repetition time steady-state spoiled multigradient-echo sequence and baseline R1 and B1 measurements. The accuracy of the approach was evaluated in simulations and a phantom experiment. The sensitivity and specificity of the method were demonstrated in one volunteer and in four patients with intracranial tumors during carbogen inhalation. We utilized (ΔR2*, ΔR1) scatter plots to analyze the multiparametric response amplitude of each voxel within an area of interest. In normal tissue R2* decreased and R1 increased moderately in response to the elevated blood and tissue oxygenation. A strong negative ΔR2* and ΔR1 response was observed in veins and some tumor areas. Moderate positive ΔR2* and ΔR1 response amplitudes were found in fluid-rich tissue as in cerebrospinal fluid, peritumoral edema, and necrotic areas. The multiparametric approach was shown to increase the specificity and sensitivity of oxygen-enhanced MRI compared to measuring ΔR2* or ΔR1 alone. It is thus expected to provide an optimal tool for the identification of tissue areas with low oxygenation, e.g., in tumors with compromised oxygen supply.

Dual-source radiofrequency transmission with patient-adaptive local radiofrequency shimming for 3.0-T cardiac MR imaging: initial experience.

PURPOSE: To evaluate the effect of dual-source parallel radiofrequency (RF) transmission with patient-adaptive local RF shimming on image quality, image contrast, and diagnostic confidence at routine clinical cardiac magnetic resonance (MR) imaging with use of a 3.0-T dual-channel transmit whole-body MR system. MATERIALS AND METHODS: Written informed consent was obtained from all patients, and the study protocol was approved by the local institutional review board. Cardiac MR imaging was performed in 28 patients by using a 3.0-T MR unit equipped with a dual-source RF transmission system. The effect of conventional versus dual-source RF transmission on steady-state free precession (SSFP) cine sequences and turbo spin-echo (TSE) black-blood (BB) sequences was evaluated. The homogeneity of the B1 field and contrast-to-noise ratios (CNRs) were measured and tested for statistical significance with the paired t test. Images were analyzed qualitatively for homogeneity, the presence of off-resonance artifacts, and diagnostic confidence independently by two readers. Statistical significance was assessed with the Wilcoxon signed rank test. Inter- and intraobserver agreement was assessed with κ statistics. RESULTS: Quantitative image analysis revealed that B1 homogeneity and CNR were significantly improved for images acquired with dual-source RF transmission compared with conventional RF transmission (P = .005). The quality of SSFP and TSE BB images of the left and the right ventricles showed a significant improvement with respect to image homogeneity and diagnostic confidence as evaluated by the readers (P = .0001, κ > 0.74). As a side effect, off-resonance artifacts were significantly reduced on SSFP images (P = .0001, κ > 0.76). CONCLUSION: Dual-source parallel RF transmission significantly improves image homogeneity, image contrast, and diagnostic confidence compared with conventional RF transmission of cardiac SSFP and TSE BB sequences.

Diffusion-weighted whole-body MRI with background body signal suppression: technical improvements at 3.0 T.

PURPOSE: To improve image quality of diffusion-weighted body magnetic resonance imaging (MRI) with background body signal suppression (DWIBS) at 3.0 T. MATERIALS AND METHODS: In 30 patients and eight volunteers, a diffusion-weighted spin-echo echo-planar imaging sequence with short TI inversion recovery (STIR) fat suppression was applied and repeated using slice-selective gradient reversal (SSGR) and/or dual-source parallel radiofrequency (RF) transmission (TX). The quality of diffusion-weighted images and gray scale inverted maximum intensity projections (MIP) were visually assessed by intraindividual comparison with respect to the level of fat suppression and signal homogeneity. Moreover, the contrast between lesions/lymph nodes and background (C(lb)) was analyzed in the MIP reconstructions. RESULTS: By combining STIR with SSGR, fat suppression was significantly improved (P < 0.001) and C(lb) was increased two times. The use of TX allowed the reduction of acquisition time and improved image quality with regard to signal homogeneity (P < 0.001) and fat suppression (P = 0.005). CONCLUSION: DWIBS at 3.0 T can be improved by using SSGR and TX.

Simultaneous MR arteriography and venography with blood pool contrast agent detects deep venous thrombosis in suspected arterial disease.

OBJECTIVE: The purpose of this study was to investigate the prevalence of incidental deep venous thrombosis (DVT) in patients with clinically suspected peripheral arterial occlusive disease (PAOD) using contrast-enhanced MR angiography (MRA) with a blood pool contrast agent. SUBJECTS AND METHODS: Two hundred fifty-nine MRA examinations with blood pool contrast agent in 245 consecutive patients (161 men; age range, 36-92 years), yielding a total of 4102 assessable arterial and venous vessel segments, were assessed with regard to the rate of incidentally observed acute and organized DVT and arterial stenosis grades. Incidental DVT was confirmed using duplex ultrasound. Contralateral nondiseased veins served as internal controls. The relationship between PAOD stages and acute and organized DVT was investigated using chi-square tests and a Mann-Whitney U test. RESULTS: Arterial stenosis grading using MRA with blood pool contrast agent revealed less than 50% luminal stenosis in 78% of segments (3199/4102), 50% or greater stenosis in 8% of segments (317/4102), and occlusion in 14% of segments (586/4102). Incidental DVT was observed in 26 of 245 patients (11%) (acute DVT was seen in 10 patients and 26 segments; organized DVT was seen in 17 patients and 35 segments; and one patient had both acute and organized DVT). All incidentally diagnosed cases of DVT were confirmed by duplex ultrasound. Internal controls revealed no false-positive or -negative findings (26 patients and 172 segments). Incidental acute DVT was significantly more common among patients without arterial stenosis greater than 50% (p < 0.05). Otherwise, there was no significant relationship between Fontaine PAOD stages and the occurrence of acute (p = 0.688) or organized (p = 0.995) DVT. CONCLUSION: Incidental DVT was prevalent in 11% of patients with clinically suspected PAOD. MRA with blood pool contrast agent has a potential role in the simultaneous assessment of arteries and veins and can detect concomitant venous disease affecting therapeutic management.