Martin Jonczyk

Non-invasive ECG-triggered 2D TOF MR angiography of the pelvic and leg arteries in an open 1.0-tesla high-field MRI system in comparison to conventional DSA

Abstract Objectives: A non-contrast-enhanced 2D time-of-flight magnetic resonance angiography (TOF-MRA) protocol was compared with the gold standard of planar digital subtraction angiography (DSA) by calculating correlations of vessel diameters. Methods: A total of 1134 vascular diameters in 81 corresponding sites were prospectively measured by TOF-MRA and DSA in seven patients (four women, three men; mean age, 68 years). For a total of 162 vascular segments per patient, 81 Spearman’s ρ correlation coefficients were calculated, consolidated to 41 due to consideration of symmetry (right/left), and assessed by correlation quality. Results: In the 41 consolidated segments, correlations were good, very good, and excellent in 25 segments (n=10>0.5, n=4>0.7, and n=11>0.8), moderate to poor in seven segments (n=4>0.3 and 0<n=3≤0.3), without in two, inverse in three, and nonmeasurable in four segments. Correlations were best for the main arteries above the knee, and these arteries were most consistently visualized. Conclusion: The TOF-MRA protocol presented here can be performed in an open 1.0-T MRI system in 60–90 min. Visualization is degraded when the target artery leaves the plane orthogonal to the imaging plane (1) or signal yield is poor due to small caliber (2).

Interactive near-real-time high-resolution imaging for MR-guided lumbar interventions using ZOOM imaging in an open 1.0 Tesla MRI system – initial experience

Abstract Purpose: Different techniques for magnetic resonance-guided lumbar interventions have been introduced in recent years. Appropriate pulse sequence design is crucial since high spatial resolution often comes at the cost of lower temporal resolution. The purpose of this study was to evaluate the value of accelerated reduced field of view (ZOOM)-based imaging sequences for lumbar interventions. Methods: ZOOM imaging was used in 31 interventions (periradicular, facet joint, epidural infiltrations, and discography) performed in 24 patients (10 women, 14 men; age 43±13.3 years). Signal-to-noise ratio and contrast-to-noise ratio (CNR) were determined and retrospectively compared with standard preinterventional (T2 weighted), peri-interventional (proton density), and postinterventional (spectral presaturation with inversion recovery [SPIR]) imaging. Needle artifacts were assessed by direct measurement as well as with parallel and perpendicular needle profiles. Puncture times were compared to similar interventions previously performed in our department. Results: No significant differences in signal intensities (standard/ZOOM: 152.0/151.6; p=0.136) and CNR values (2.0/4.0; p=0.487) were identified for T2-weighted sequences. The needle artifact signal intensity was comparable (648.1/747.5; p=0.172) for peri-interventional imaging. Standard interventional (fat needle: 43.8/23.4; p<0.001; muscle needle: 6.2/2.4; p<0.001) and SPIR sequences (43.3/13.9; p=0.010) showed a higher CNR than corresponding ZOOM sequences did. Needle artifacts were larger in ZOOM (2.4 mm/2.9 mm; p=0.005). The profiles revealed that ZOOM imaging delivers more overall signal intensity. The turning points of both profiles were comparable. ZOOM reduced intervention times significantly (329.1 s/228.5 s; p=0.026). Conclusion: ZOOM imaging is a feasible interactive sequence for lumbar interventions. It ameliorates the tradeoff between image quality and temporal resolution. Moreover, the sequence design reduces intervention times significantly.

Tailored interactive sequences for continuous MR-image-guided freehand biopsies of different organs in an open system at 1.0 tesla (T) – Initial experience

Abstract Objectives: To assess the feasibility, image quality, and accuracy of freehand biopsies of liver, bone, muscle, vertebral disc, soft tissue, and other lesions using balanced steady-state free precession (SSFP, balanced fast field echo: bFFE), spoiled and nonspoiled gradient echo (FFE), and turbo spin echo (TSE) sequences for interactive continuous navigation in an open magnetic resonance imaging (MRI) system at 1.0 tesla (T). Methods: Twenty-six MR-guided biopsies (five liver, five bone, four muscle, four vertebral disc, one lung, one kidney, one suprarenal gland, and five soft or other tissue) were performed in 23 patients in a 1.0-T open magnetic resonance (MR) scanner (Panorama HFO, Philips Healthcare, Best, the Netherlands). A total of 42 samples were obtained. Depending on lesion size and location, 14–18-gauge MR-compatible biopsy sets with a length of 100 or 200 mm (Somatex Medical, Teltow, Germany), 14–18-gauge MR-compatible semiautomatic biopsy guns with a length of 100 or 150 mm (Invivo, Schwerin, Germany), or 11-gauge MR-compatible bone marrow biopsy needles with a length of 100 mm (Somatex Medical, Teltow, Germany) were employed. Results: All lesions were visible with continuous interactive imaging. Our initial results indicate that bFFE is particularly suitable for fast-moving organs (pulmonary, paracardial); moving organs are targeted better with T1-weighted (T1W) TSE, T1W FFE (liver) or T2-weighted (T2W) TSE (complicated cysts, adrenal glands), and static organs are successfully approached with proton density (PD) (spine) or T1W TSE (peripheral bones, musculoskeletal system). No adverse events related to the use of MRI were obtained. No complications occurred according to the Society of Interventional Radiology (SIR) clinical practice guidelines. Conclusion: Applying tailored interactive dynamic imaging sequences for continuous navigation to liver, bone, muscle, vertebral disc, soft tissue, and other lesions can improve the feasibility, image quality, and interventional accuracy of freehand MR-guided biopsies and may hence reduce the risk of complications.

The impact of imaging speed of MR-guided punctures and interventions in static organs—A phantom study

PURPOSE Verification of MR-guidance with image acquisitions slower than 1 image per second as it is inevitable for some interventions. Therefore, we quantified solely the effect of acquisition-time on the efficiency of MR-guided interventions in a static phantom study. MATERIALS AND METHODS We measured the duration, accuracy and error rate of simulated interventions for different acquisition-times using a simplified interventional setup. All measurements were performed in a 1.0 T open MRI scanner. Imaging was performed with a gradient-echo sequence (flipangle=20°; TR/TE=12/6 ms; voxelsize=1 mm×1 mm; slicethickness=5 mm; FOV=230 mm×200 mm; acquisition-time=1 s). Variable acquisition times were simulated with intermediate pauses of 0, 1, 2, 3, 4 and 5 s. The interventions were performed by a total of 20 volunteers including 7 experienced interventionalists. RESULTS The mean duration of the intervention was 2 min. Significant differences between experienced and unexperienced volunteers were limited to the localization of the image plane and corrections made. The mean accuracy was 5.6 mm. The time to localize the image plane increased with deceleration of imaging from 24 s to 49 s. A similar increase was observed for the intervention time (55-108 s). A significant influence of the acquisition-time on durations and corrections was only found with acquisition-times greater than 4s per image. CONCLUSION Even image rates of several seconds per image are sufficient enough for efficient interventions in static organs. Thus, the main attention has to be turned on the visibility of the needle when sequences are optimized for MR-guidance. The minimization of imaging speed is rather of secondary interest.

Primary and metastatic malignancies of the lung: Retrospective analysis of the CT-guided high-dose rate brachytherapy (CT-HDRBT) ablation in tumours <4 cm and ≥4 cm

BACKGROUND Minimal invasive local therapies are alternative treatment options in patients with primary and metastatic lung malignancies being not eligible for resection. However, thermal ablations are often limited by large tumour volumes. PURPOSE To evaluate the efficacy and safety of CT-HDRBT in pulmonary tumours ≥4 cm compared to smaller tumours. MATERIAL AND METHODS In this retrospective study, 74 consecutive patients (mean age: 63 ± 12; m: 39, w: 35) with a total of 175 tumours treated in 132 interventions were enrolled between October 2003 and September 2016. Primary and assisted local tumour control (LTC), progression free survival (PFS) and overall survival (OS) after first CT-HDBRT were identified for two subgroups with tumours <4 cm (A) as well as ≥4 cm (B) using the Kaplan-Meier-Method. Radiation parameters and side effects were recorded. Log-Rank-Test and Mann-Whitney-U-Test were performed for statistical analyses with p-values <0.05 considered as significant. RESULTS There was no statistical difference in coverage with prescribed radiation dose (A:19.78 ± 8.62 mm (range 5-39 mm), 99.56 ± 0.99%; B:61.70 ± 21.09 mm (41-100 mm), 94.81 ± 7.19%, p = 0.263). LTC rates after 0.5-,1-,2-,3- and 5-years were higher in A compared to B (A:85%/74%/63%/60%/46%, B:71%/37%/32%/32%/32%) with longer primary (A:11months, B:5months, p = 0.003) and assisted LTC (A:9months B:20months, p = 0.339). Longer OS was observed in A (A:18.5months, B:14.5months, p = 0.011) with longer OS rates (A:96%/87%/60%/48%/19%, B:92%/73%/20%/20%/0%). Complication assessment revealed no bleedings, 16.6% pneumothoraxes and 48.5% of mild radiation fibrosis without clinical symptoms. CONCLUSION In conclusion, higher LTC and OS were observed in patients with primary lung malignancies <4 cm. Nevertheless, CT-HDRBT is a safe and feasible alternative even in larger tumours ≥4 cm.

Cholangiocarcinoma: CT-guided High-Dose Rate Brachytherapy (CT-HDRBT) for Limited ( 4 cm) Tumors

Background/Aim: Thermal-ablative therapies are limited to tumors of 3-4 cm diameter. The purpose of this study was to evaluate the local tumor control (LTC) of CT-guided High-Dose-Rate-Brachytherapy (CT-HDRBT) for ablation of cholangiocarcinomas (CCA) ≥4 cm compared to smaller tumors. Patients and Methods: Sixty-one patients (tumors: 142, interventions: 91) were treated from March 2008 to January 2017. LTC, progression-free survival (PFS) and overall survival (OS) after first CT-HDRBT were identified for two subgroups (A:<4 cm, B:≥4 cm) and the influence of coverage and target-dose were evaluated. Log-Rank- and Mann-Whitney-U-Tests were performed for statistical analyses with p-values <0.05 considered as significant. Results: Better coverage was achieved for smaller tumors (A: 99.22-0.25%, B: 95.10-1.40%, p<0.001). LTC was better in subgroup A (A: 8, B: 6 months, p=0.006). Larger tumors (4-7 cm) with incomplete coverage showed the poorest LTC (p=0.032). There were no statistical significances in PFS (A: 5, B: 3 months, p=0.597) and OS (A:15.5; B:10.0 months, p=0.107). Conclusion: CT-HDRBT is sufficient in CCA ≥4 cm, if full coverage with therapeutic doses can be achieved.

Radiation exposure during TACE procedures using additional cone-beam CT (CBCT) for guidance: safety and precautions:

Background During transarterial chemoembolization (TACE), cone-beam computed tomography (CBCT) can be used for tumor and feeding vessel detection as well as postembolization CT imaging. However, there will be additional radiation exposure from CBCT. Purpose To evaluate the additional dose raised through CBCT-assisted guidance in comparison to TACE procedures guided with pulsed digital subtraction angiography (DSA) alone. Material and Methods In 70 of 140 consecutive patients undergoing TACE for liver cancer, CBCT was used to facilitate the TACE. Cumulative dose area product (DAP), cumulative kerma(air), DAP values of DSA, total and cine specific fluoroscopy times (FT) of 1375 DSA runs, and DAP of 91 CBCTs were recorded and analyzed using Spearmans correlation, Mann–Whitney U-test, and Kruskal–Wallis test. P values < 0.05 were considered significant. Results Additional CBCT increased DAP by 2% (P = 0.737), kerma(air) by 24.6% (P = 0.206), and FT by 0.02% (P = 0.453). Subgroup analysis revealed that postembolization CBCT for detection of ethiodized oil deposits added more DAP to the procedure. Performing CBCT-assisted TACE, DSA until first CBCT contributed about 38% to the total DAP. Guidance CBCT acquisitions conduced to 6% of the procedures DAP. Additional DSA for guidance after CBCT acquisition required approximately 46% of the mean DAP. The last DSA run for documentation purposes contributed about 10% of the DAP. Conclusion CBCT adds radiation exposure in TACE. However, the capability of CBCT to detect vessels and overlay in real-time during fluoroscopy facilitates TACE with resultant reduction of DAPs up to 46%.

Teleradiologische Prozess- und Untersuchungszeiten@@@Teleradiological report turnaround times: Eine institutsinterne Effizienz- und Qualitätsanalyse@@@An internal efficiency and quality control analysis

AIMS The teleradiological examinations performed at the Charité were analyzed for the purpose of internal quality and efficiency control. Data included the type and number of examinations performed, the time of day and week the examination was performed and the differences in teleradiologist report turnaround times. MATERIAL AND METHODS A retrospective analysis of the radiology information system (RIS) database of all teleradiological computed tomography examinations performed at the Charité from 2011 through 2013 was carried out. The search retrieved 10,200 teleradiological examinations which were included in the analysis. The records were analyzed for the time of the day and week the examination was performed, the interval between examination and time of reporting, the type of teleradiological examination and the campus in which they were performed. RESULTS The number of teleradiological examinations performed increased continuously during the observation period. Computed tomography of the head was the most frequently performed type of examination with 86%. Taking all forms of examination into consideration it took an average of 34 min until a report was written. Over the 3-year observation period the times remained virtually unaltered. CONCLUSION During the 3-year observation period nearly constant report times could be observed in spite of the increased numbers of examinations. This indicates an efficiency enhancement and rational integration of teleradiology into the radiological workflow.

[Teleradiological report turnaround times: An internal efficiency and quality control analysis].

AIMS The teleradiological examinations performed at the Charité were analyzed for the purpose of internal quality and efficiency control. Data included the type and number of examinations performed, the time of day and week the examination was performed and the differences in teleradiologist report turnaround times. MATERIAL AND METHODS A retrospective analysis of the radiology information system (RIS) database of all teleradiological computed tomography examinations performed at the Charité from 2011 through 2013 was carried out. The search retrieved 10,200 teleradiological examinations which were included in the analysis. The records were analyzed for the time of the day and week the examination was performed, the interval between examination and time of reporting, the type of teleradiological examination and the campus in which they were performed. RESULTS The number of teleradiological examinations performed increased continuously during the observation period. Computed tomography of the head was the most frequently performed type of examination with 86%. Taking all forms of examination into consideration it took an average of 34 min until a report was written. Over the 3-year observation period the times remained virtually unaltered. CONCLUSION During the 3-year observation period nearly constant report times could be observed in spite of the increased numbers of examinations. This indicates an efficiency enhancement and rational integration of teleradiology into the radiological workflow.

Volume comparison of radiofrequency ablation at 3- and 5-cm target volumes for four different radiofrequency generators: MR volumetry in an open 1-T MRI system versus macroscopic measurement

Abstract Introduction: In a patient, it is usually not macroscopically possible to estimate the non-viable volume induced by radiofrequency ablation (RFA) after the procedure. The purpose of this study was to use an ex vivo bovine liver model to perform magnetic resonance (MR) volumetry of the visible tissue signal change induced by RFA and to correlate the MR measurement with the actual macroscopic volume measured in the dissected specimens. Materials and methods: Sixty-four liver specimens cut from 16 bovine livers were ablated under constant simulated, close physiological conditions with target volumes set to 14.14 ml (3-cm lesion) and 65.45 ml (5-cm lesion). Four commercially available radiofrequency (RF) systems were tested (n=16 for each system; n=8 for 3 cm and n=8 for 5 cm). A T1-weighted turbo spin echo (TSE) sequence with inversion recovery and a proton-density (PD)-weighted TSE sequence were acquired in a 1.0-T open magnetic resonance imaging (MRI) system. After manual dissection, actual macroscopic ablation diameters were measured and volumes calculated. MR volumetry was performed using a semiautomatic software tool. To validate the correctness and feasibility of the volume formula in macroscopic measurements, MR multiplanar reformation diameter measurements with subsequent volume calculation and semiautomatic MR volumes were correlated. Results: Semiautomatic MR volumetry yielded smaller volumes than manual measurement after dissection, irrespective of RF system used, target lesion size, and MR sequence. For the 3-cm lesion, only 43.3% (T1) and 41.5% (PD) of the entire necrosis are detectable. For the 5-cm lesion, only 40.8% (T1) and 37.2% (PD) are visualized in MRI directly after intervention. The correlation between semiautomatic MR volumes and calculated MR volumes was 0.888 for the T1-weighted sequence and 0.875 for the PD sequence. Conclusion: After correlation of semiautomatic MR volumes and calculated MR volumes, it seems reasonable to use the respective volume formula for macroscopic volume calculation. Hyperacute MRI after ex vivo intervention may result in the underestimation of the real expansion of the produced necrosis zone. This must be kept in mind when using MRI for validating ablation success directly after RFA. One reason for the discrepancy between macroscopic and MRI appearance immediately after RFA may be that the transitional zone shows no or only partially visible MR signal change.