Feasibility study of 2D Dixon-Magnetic Resonance Fingerprinting (MRF) of breast cancer.

Purpose: Application of MRF to evaluate the feasibility of 2D Dixon blurring-corrected MRF (2DDb-cMRF) to differentiate breast cancer (BC) from normal fibroglandular tissue (FGT). Methods: Prospective study on 14 patients with unilateral BC on 1.5 T system/axial T2w-TSE sequence, 2DDb-cMRF, B1 map, dynamic contrast-enhanced (DCE) T1-w GE-series. Mean T1 and T2 values and standard deviations were computed in the BC-/FGT-ROI on pre-/post-contrast MRF-maps and their differences were tested by two-tailed student t-test.Accuracy and repeatability of MRF were evaluated in a phantom experiment with gelatin with Primovist surrounded by fat.The T1 reduction between pre-/post-contrast MRF-maps was correlated to DCE signal enhancement in the last image post-contrast through the Pearson´s correlation coefficient (r) and for the phantom validation experiment through the Lin's concordance correlation coefficient (CCC).Visual evaluation of cancers on MRF-Maps was performed by rating each MRF-Map by 3 radiologists. Results: T1- and T2-MRF values of BC vs. FGT were for T1 and T2 pre-contrast respectively: 1147 ± 1 ms vs. 1052 ± 9 ms (p = 0.007) and 83 ± 1 ms vs. 73 ± 1 ms (p = 0.03); post-contrast respectively: 367.3 ± 121.5 ms vs. 690.3 ± 200.3 ms (p = 0.0005) and 76.9 ± 11.5 ms vs. 69.8 ± 15.2 ms (p = 0.12). r was positive (FGT r = 0.7; BC r = 0.6). CCC was 0.999 for T1 and 0.994 for T2. In the T1- and T2-MRF-Maps before contrast respectively (7,7,8)/14 and (5,9,8)/14 cancers were visible to the readers; afterwards, (11,12,12)/14 and (5,6,11)/14. Conclusions: MRF is promising for distinction between BC and FGT as well as for analyzing pre-/post-contrast T1 changes. However, its potential for differential diagnosis warrants further studies.

Recurrent Colorectal Liver Metastases in the Liver Remnant After Major Liver Surgery-IRE as a Salvage Local Treatment When Resection and Thermal Ablation are Unsuitable.

PURPOSE: To examine the safety and short-term oncologic outcomes of computer-tomography-guided (CT-guided) irreversible electroporation (IRE) of recurrent, irresectable colorectal liver metastases (CRLM) after major hepatectomy deemed unsuitable for thermal ablation. PATIENTS AND METHODS: Twenty-three patients undergoing CT-guided IRE of recurrent CRLM after major hepatectomy were included in this study. All tumors were located adjacent to sole remaining intrahepatic blood vessels and bile ducts, precluding thermal ablation. Patients underwent systematic clinical and imaging follow-up, including magnetic resonance imaging of the liver at 1-month and 3-month intervals thereafter. Time to local and intrahepatic tumor progression within 12 and 36 months and associated risk factors were assessed using Kaplan Meier and Cox regression analysis, respectively. RESULTS: Complete ablation with a safety margin of at least 0.5 cm was achieved in 22/23 (95.6%) patients. No vessel injury or thrombosis occurred. Five patients developed moderate biliary stenosis after a median of 4 weeks, without requiring treatment. Local tumor-progression-free rates within 12/36 months were 64%/57.4%, respectively. Intrahepatic-progression-free rate within 12/36 months was 36.4%/19.5%, respectively. Five (23%) patients were tumor-free at the end of follow-up. Multivariate Cox regression analysis did not show any association between local tumor-progression-free rates and patient age, target tumor size, primary tumor side or synchronicity of liver metastases. CONCLUSION: In this highly selected patient population with local recurrences of CRLM after major surgery, IRE was shown to be a safe salvage treatment option when thermal ablation is unsuitable.

Midterm Safety and Efficacy of Irreversible Electroporation of Malignant Liver Tumors Located Close to Major Portal or Hepatic Veins.

Purpose To investigate the efficacy and safety of irreversible electroporation (IRE) in the treatment of hepatic tumors not suitable for thermal ablation (radiofrequency ablation [RFA] or microwave ablation). Materials and Methods This was an institutional review board-approved prospective study in 29 patients (15 men, 14 women; mean age, 63 years ± 12 [standard deviation]) with 43 primary (n = 8) or secondary (n = 35) malignant liver tumors who underwent computed tomography (CT)-guided IRE. All target tumors were located immediately adjacent to major hepatic veins, portal veins, or both; thus, they were not considered suitable for RFA or microwave ablation. Patients underwent postinterventional CT and magnetic resonance (MR) imaging. Systematic follow-up MR imaging was performed for 24 months on average to assess complete ablation, intrahepatic tumor recurrence, and complications. The 95% confidence intervals (CIs) were determined for the rate of bile duct strictures, incomplete ablation, and tumor recurrence. Results Complete ablation was achieved in 40 (93%; 95% CI: 85, 100) of 43 target tumors, with a safety margin of 5-10 mm, and was confirmed at immediate postinterventional CT and MR imaging. In 13 (33%; 95% CI: 18, 47) of 40 completely ablated tumors, intrahepatic tumor recurrence was observed at 2-18 months. However, only two (15%; 95% CI: 0, 35) of these 13 tumors were observed within the ablation zone. In the remaining 11 (85%; 95% CI: 65, 100), tumor growth was observed alongside the needle tract. None of the two true local recurrences occurred at the site of the vessel. All adjacent vessels remained perfused at follow-up. Five (24%; 95% CI: 5, 39) of 21 patients with target tumors adjacent to portal veins developed mild to moderate cholestasis 2-6 weeks after IRE. Conclusion IRE is useful to avoid incomplete ablation secondary to heat-sink effects and damage to major blood vessels; however, needle tract seeding is observed in 26% of treated tumors, and IRE induces sufficient local heating to bile ducts in 24% of ablations. © RSNA, 2017.

Magnetic Resonance Imaging Findings After Percutaneous Irreversible Electroporation of Liver Metastases: A Systematic Longitudinal Study.

OBJECTIVE: The aim of this study was to systematically investigate the course of magnetic resonance (MR) signal intensity (SI) changes that occur in noncirrhotic livers after irreversible electroporation (IRE) of liver metastases. METHODS: This study is an institutional review board-approved prospective longitudinal follow-up study on 27 patients with 37 liver metastases who underwent computed tomography-guided percutaneous IRE and a standardized follow-up protocol by serial hepatic MR imaging studies that consisted of a gadobutrol-enhanced dynamic series, axial T2-weighted (T2w) turbo spin echo, and diffusion-weighted imaging (b = 0/50/800), acquired before, within 2, and at 24 hours after IRE; at 1, 2, 4, 6, 8, and 12 weeks after IRE; and every 3 months thereafter for a follow-up of at least 12 months. RESULTS: The ablated target lesion remained visible within the ablation zone in 23 (62%) of 37 of cases for a mean time of 21 ± 20 weeks (median, 12 weeks). The ablation zone appeared homogeneously hyperintense on T2w turbo spin echo images on the day of IRE in 37 of 37 cases. By 24 hours after IRE, the ablation zone inverted its SI in 35 of 37 cases to intermediately hypointense, with a rim of T2w bright SI that exhibited arterial phase enhancement; this persisted for 7 ± 5 weeks (median, 4 weeks). The rim resolved in 35 (95%) of 37 cases within 3 months. The ablation zone increased slightly over the first 48 hours, then shrank progressively. Complete healing of the ablation zone was observed in 57% (21/37) after an average of 14 ± 15 (median, 8 weeks).Average apparent diffusion coefficient values of the ablation zone decreased from 0.74 ± 0.36 × 10 mm/s pre-IRE to 0.63 ± 0.27 × 10 mm/s within the first 24 hours (P < 0.05), followed by a progressive normalization to 0.91 ± 0.30 × 10 mm/s at 2 months. CONCLUSIONS: Knowledge of the broad spectrum of MR imaging findings after IRE is important to avoid diagnostic errors in the follow-up of patients after IRE.

Digital breast tomosynthesis-guided vacuum-assisted breast biopsy: initial experiences and comparison with prone stereotactic vacuum-assisted biopsy.

PURPOSE: To use digital breast tomosynthesis (DBT)-guided vacuum-assisted biopsy (VAB) to sample target lesions identified at full-field digital screening mammography and compare clinical performance with that of prone stereotactic (PS) VAB. MATERIALS AND METHODS: In this institutional review board-approved study, 205 patients with 216 mammographic findings suspicious for cancer were scheduled to undergo mammography-guided VAB. Written informed consent was obtained. PS VAB was performed in 159 patients with 165 target lesions. DBT VAB was performed in 46 consecutive patients with 51 target lesions. Tissue-sampling methods and materials (9-gauge needles) were the same with both systems. For calcifications, specimen radiographs were obtained, and for masses or architectural distortions, control mammography or DBT was performed to confirm adequate target lesion sampling. χ(2) and Student t tests were used to compare biopsy time, and the Fisher exact test was used to compare lesion type distribution for DBT versus PS VAB. RESULTS: Technical success was achieved in 51 of 51 lesions (100%) with DBT VAB versus 154 of 165 lesions (93%) with PS VAB. In one of 11 lesions in which PS VAB failed, DBT VAB was performed successfully. Mean time to complete VAB was 13 minutes ± 3.7 for DBT VAB versus 29 minutes ± 10.1 for PS VAB (P < .0001). Reidentifying and targeting lesions during PS VAB took longer than it did during DBT VAB (P < .0001). Tissue sampling took about the same time for PS VAB and DBT VAB (P = .067). Significantly more "low-contrast" (ie, uncalcified) target lesions were biopsied with DBT VAB (13 of 51 lesions) versus PS VAB (nine of 165 lesions) (P < .0002). No major complications were observed with either system. One patient who underwent DBT VAB in the sitting position and one patient who underwent PS VAB developed self-limiting vasovagal reactions. CONCLUSION: Clinical performance of DBT VAB was significantly superior to PS VAB. Because DBT VAB allows use of the full detector size for imaging and provides immediate lesion depth information without requiring triangulation, it facilitates target lesion reidentification and sampling of even low-contrast targets, such as uncalcified masses.

First in-human magnetic resonance visualization of surgical mesh implants for inguinal hernia treatment.

OBJECTIVES: Until today, there have been no conventional imaging methods available to visualize surgical mesh implants and related complications. In a new approach, we incorporated iron particles into polymer-based implants and visualized them by magnetic resonance imaging (MRI).After clinical approval of such implants, the purposes of this study were to evaluate the MRI conspicuity of such iron-loaded mesh implants in patients treated for inguinal hernias and to assess the immediate postsurgical mesh configuration. MATERIALS AND METHODS: Approved by the ethics committee, in this prospective cohort study, 13 patients (3 patients with bilateral hernia treatment) were surgically treated for inguinal hernia receiving iron-loaded mesh implants between March and October 2012. The implants were applied via laparoscopic technique (transabdominal preperitoneal technique; n = 8, 3 patients with bilateral hernia treatment) or via open surgical procedure (Lichtenstein surgery; n = 5). Magnetic resonance imaging was performed 1 day after the surgery at a 1.5-T scanner (Achieva; Philips, Best, The Netherlands) with a 16-channel receiver coil using 3 different gradient echo sequences (first gradient echo sequence, second gradient echo sequence, and third gradient echo sequence [GRE1-3]) and 1 T2-weighted turbo spin-echo sequence (T2wTSE). Three radiologists independently evaluated mesh conspicuity and diagnostic value with respect to different structures using a semiquantitative scoring system (1, insufficient; 2, sufficient; 3, good; 4, optimal). Mesh deformation and coverage of the hernia were visually assessed and rated using a 5-point semiquantitative scoring system. Statistical analysis was performed using mixed models and linear contrast. RESULTS: All 16 implants were successfully visualized by MRI. On gradient echo sequences, the mesh is clearly delineated as a thick hypointense line. On T2wTSE, the mesh was depicted as a faint hypointense line, which was difficult to identify. The first gradient echo sequence was rated best for visual conspicuity (mean [SD], 3.8 [0.4]). T2-weighted turbo spin-echo sequence was preferred for evaluation of the surrounding anatomy (mean [SD], 3.7 [0.3]). For the combined assessment of both mesh and anatomy, GRE3 was rated best (mean [SD], 2.9 [0.7]). Local air slightly reduced mesh delineation (lowest mean [SD] rating, 2.9 [0.7] for GRE3). Overall, in both implantation techniques, the meshes exhibited mild to moderate deformations (mean [SD], 3.3 [0.4], 3.1 [0.3], and 2.8 [0.3] on average with open technique, 2.7 [0.3], 2.7 [0.2], and 2.3 [0.3] with laparoscopic technique). Coverage of the hernia was achieved in 15 of the 16 implants. CONCLUSIONS: Combining iron-loaded implants and MRI, we achieved mesh visualization for the first time in patients. For MRI protocol, we propose a combination of different gradient echo sequences and T2-weighted turbo spin-echo sequences: first gradient echo sequence for mesh configuration, T2wTSE for anatomy assessment, and GRE3 for evaluation of hernia coverage and mesh localization. Using our approach, MRI could become a noninvasive alternative to open surgical exploration if mesh-related complications were suspected.

Early detection of acute mesenteric ischemia using diffusion-weighted 3.0-T magnetic resonance imaging in a porcine model.

PURPOSE: The aim of this study was to investigate if 3.0-T diffusion-weighted magnetic resonance imaging (MRI) can be used for early detection of acute occlusive and nonocclusive mesenteric ischemia. MATERIALS AND METHODS: In this study, approved by the official committee on animal affairs, proximal (occlusive) mesenteric ischemia and peripheral (nonocclusive) mesenteric ischemia were induced in 8 and 2, respectively, female domestic pigs. Proximal mesenteric ischemia was induced by intra-arterial injection of n-butyl-cyanoacrylate in the superior mesenteric artery or 1 of its main branches; peripheral mesenteric ischemia was induced by intra-arterial injection of microparticles. Before embolization and at 30-, 60-, and 90-minute intervals after embolization, diffusion-weighted imaging was performed, and apparent diffusion coefficient (ADC) maps were calculated on a clinical 3.0-T system. Immediately after the last MRI session, animals were killed to provide a pathological correlation for mesenteric ischemia. RESULTS: Ischemic bowel parts appeared hyperintense on diffusion-weighted images and hypointense on the corresponding ADC maps. Mean diffusion-weighted imaging signal intensity increased and ADC decreased significantly within 30 minutes after embolization (P < 0.001) and remained unchanged until 90 minutes after injury, independent of the embolization method. CONCLUSIONS: 3.0-Tesla diffusion-weighted MRI may help detect acute mesenteric ischemia as early as 30 minutes after vessel occlusion.