MR-guided core biopsies using a closed 1.0 T imager. First clinical results.

OBJECTIVE: High soft-tissue contrast and multiplanar imaging capabilities of MRI may be advantageous in biopsy guidance compared to CT. We report our first results with MR-guided core biopsies using a closed 1.0 T MR imager. METHODS AND PATIENTS: In ten patients, seven liver lesions and one lesion each in the muscle of the back, the gluteal muscle and in the breast were biopsied under MR guidance using MR-compatible needles (Tru-Cut type, 18G and 14G). For control scans T1-weighted turbo-spin-echo (TSE), gradient-echo and T2-weighted TSE sequences were used. RESULTS: In all patients, the suspicious lesions and the biopsy needle were exactly delineated in MR control scans. In nine out of ten patients, the suspicious lesion was clarified histologically. Controls of needle position in a second plane were performed twice. Pushing the inner stylet alone resulted in a distortion of the needle in several cases in its flat area. The small diameter of the MR gantry was inconvenient for a few patients. One complication (intrahepatic bleeding) was observed, which healed up without consequences. CONCLUSION: Using a closed 1.0 T MR imager MR-guided core biopsies can be conducted efficiently. Core biopsies should be taken by pulling and pushing the outer cannula. Advantageous compared to CT are the multiplanar imaging capabilities, while the smaller gantry is disadvantageous.     

MR-guided biopsies with a newly designed cordless coil in an open low-field system: Initial findings

The purpose of this study was to examine the feasibility and safety of MR-guided biopsies with a newly designed cordless coil in an open low-field magnetic resonance (MR) system. Eleven patients were biopsied using a low-field system (0.2 T, Magnetom Concerto, Siemens) by using the new cordless coil (Siemens). The biopsies were performed in different organ systems [liver (n=7), abdomen (n=1), shoulder (n=1), pelvis (n=1) and hip (n=1)]. The procedures were guided using T1-weighted FLASH (fast low-angle shot) sequences. The lesions were biopsied using the coaxial technique through a 15-gauge puncture needle with a 16-gauge biopsy handy. Coil handling, image quality and complications were evaluated. Imaging quality and visualization of the lesions were optimal up to a penetration depth of 9 cm. In all cases the biopsy procedures were successfully performed with MR guidance without any complications. Pathological findings revealed seven cases of malignant tissue and four cases of non-malignant tissue. The use of the cordless coil allows improved patient access during the biopsy and an improved handling of the coil system. MR-guided biopsy using the novel cordless coil system can be performed safely and precisely with easy handling of the coil. This coil concept, however, is restricted to special indications.     

MRT-gezielte interventionelle Verfahren zur Abkl?rung des Prostatakarzinoms

In recent years magnetic resonance imaging (MRI) has been increasingly established in the diagnosis of prostate cancer in addition to transrectal ultrasonography (TRUS). The use of T2-weighted imaging allows an exact delineation of the zonal anatomy of the prostate and its surrounding structures. Other MR imaging tools, such as dynamic contrast-enhanced T1-weighted imaging or diffusion-weighted imaging allow an inference of the biochemical characteristics (multiparametric MRI). Prostate cancer, which could only be diagnosed using MR imaging or lesions suspected as being prostate cancer, which are localized in the anterior aspect of the prostate and were missed with repetitive TRUS biopsy, need to undergo MR guided biopsy. Recent studies have shown a good correlation between MR imaging and histopathology of specimens collected by MR-guided biopsy. Improved lesion targeting is therefore possible with MR-guided biopsy. So far data suggest that MR-guided biopsy of the prostate is a promising alternative diagnostic tool to TRUS-guided biopsy.     

Dynamic contrast-enhanced MR imaging and MR-guided bone biopsy on a 0.23 T open imager

OBJECTIVE: To assess the feasibility of MR (magnetic resonance)-guided bone biopsies. DESIGN AND PATIENTS: Thirty-six consecutive patients with known or suspected benign or malignant bone lesions underwent comprehensive MR imaging. A dynamic contrast-enhanced sequence followed by stationary T1-weighted sequences were obtained and MR-guided bone biopsy of the tumor at the site with fastest enhancement was performed using an open 0.23 T MR imager. RESULTS: All MR-guided bone biopsies samples were estimated to be sufficient by the pathologists. The biopsy specimens were diagnostic in 34 of 36 cases. CONCLUSION: MR-guided bone biopsies combined with dynamic contrast-enhanced imaging are feasible and safe for the diagnostic investigation of equivocal bone lesions.     

MR-guided biopsies of lesions in the retroperitoneal space: technique and results

The purpose of this study was to evaluate the safety and precision of MRI-guided biopsies of retroperitoneal space-occupying tumors in an open low-field system. In 30 patients with indistinct retroperitoneal tumors [paraaortic lesion (n=20), kidney (n=2), suprarenal gland (n=3) and pancreas (n=5)] MR-guided biopsies were performed using a low-field system (0.2 T, Magnetom Concerto, Siemens, Germany). For the monitoring of the biopsies T1-weighted FLASH sequences (TR/TE=160/5 ms; 90°) were used in all patients and modified FLASH sequences (TR/TE=160/13 ms; 90°) in ten patients. After positioning of the needle in the tumors 114 biopsy specimens were acquired in coaxial technique with 16-gauge cutting needles (Somatex, Germany). The biopsies were successfully performed in all patients without vascular or organ injuries. The visualization of the aortic blood flow with MRI facilitated the biopsy procedures of paraaortic lesions. The size of the lesions ranged from 1.6 to 7.5 cm. The median distance of the biopsy access path was 10.4 cm. Adequate specimens were obtained in 28 cases (93.3%) resulting in a correct histological classification of 27 lesions (90%). In conclusion, MR-guided biopsies of retroperitoneal lesions using an open low-field system can be performed safely and accurately and is an alternative to CT-guided biopsies.     

Diagnostic yield of MR-guided liver biopsies compared with CT- and US-guided liver biopsies

PURPOSE: To compare diagnostic yield and complication rates of magnetic resonance (MR)-guided versus computed tomography (CT)- and ultrasound (US)-guided liver biopsies. MATERIALS AND METHODS: MR-, CT-, and US-guided liver biopsies performed between 9/96 and 9/98 were compared. Sixty patients (21 men and 39 women, mean age 60 years) underwent MR-guided biopsy of liver lesions. Thirty patients (16 men and 14 women, mean age 59 years) underwent CT-guided biopsy. Eighteen patients (seven men and 11 women, mean age 50 years) underwent US-guided biopsy. MR procedures were performed in an open-configuration 0.5-T Signa SP MR unit. Lesion localization used standard T1 and T2 sequences, whereas biopsies were performed with multiplanar spoiled gradient recalled echo and fast gradient recalled echo sequences. A coaxial system with an MR-compatible 18-gauge stabilizing needle and a 21-gauge aspiration needle was used to obtain all samples. In CT and US procedures, a 19-gauge stabilizing needle and a 21-gauge aspiration or a 20-gauge core biopsy needle were used. A cytotechnologist was present to determine the adequacy of samples. RESULTS: MR had a diagnostic yield of 61%. CT and US had diagnostic yields of 67% and 61%, respectively. No serious complications were reported for MR and US procedures. Two CT biopsies resulted in postprocedural hemorrhage. One patient required surgical exploration and died. CONCLUSIONS: MR-guided biopsy of liver lesions with use of a 0.5-T open-configuration magnet is safe and accurate when compared with CT and US. No statistical difference was observed between the diagnostic yield of biopsies performed with MR, CT, and US guidance. MR enabled biopsy of a number of lesions in the hepatic dome and lesions with low contrast, which would normally be difficult to sample safely with use of CT or US.     

Prostate cancer localization with dynamic contrast-enhanced MR imaging and proton MR spectroscopic imaging

PURPOSE: To prospectively determine the accuracies of T2-weighted magnetic resonance (MR) imaging, dynamic contrast material-enhanced MR imaging, and quantitative three-dimensional (3D) proton MR spectroscopic imaging of the entire prostate for prostate cancer localization, with whole-mount histopathologic section findings as the reference standard. MATERIALS AND METHODS: This study was approved by the institutional review board, and informed consent was obtained from all patients. Thirty-four consecutive men with a mean age of 60 years and a mean prostate-specific antigen level of 8 ng/mL were examined. The median biopsy Gleason score was 6. T2-weighted MR imaging, dynamic contrast-enhanced MR imaging, and 3D MR spectroscopic imaging were performed, and on the basis of the image data, two readers with different levels of experience recorded the location of the suspicious peripheral zone and central gland tumor nodules on each of 14 standardized regions of interest (ROIs) in the prostate. The degree of diagnostic confidence for each ROI was recorded on a five-point scale. Localization accuracy and ROI-based receiver operating characteristic (ROC) curves were calculated. RESULTS: For both readers, areas under the ROC curve for T2-weighted MR, dynamic contrast-enhanced MR, and 3D MR spectroscopic imaging were 0.68, 0.91, and 0.80, respectively. Reader accuracy in tumor localization with dynamic contrast-enhanced imaging was significantly better than that with quantitative spectroscopic imaging (P < .01). Reader accuracy in tumor localization with both dynamic contrast-enhanced imaging and spectroscopic imaging was significantly better than that with T2-weighted imaging (P < .01). CONCLUSION: Compared with use of T2-weighted MR imaging, use of dynamic contrast-enhanced MR imaging and 3D MR spectroscopic imaging facilitated significantly improved accuracy in prostate cancer localization.     

MR-compatible assistance system for punction in a high-field system: device and feasibility of transgluteal biopsies of the prostate gland

We present the first cadavic study results concerning the feasibility of the use of an MR-guided assistance system, Innomotion (Innomedic, Herxheim, Germany), for accurate and consistent placement of percutaneous needles in the prostate gland. The MR-compatible assistance system consists of a C-arch, guiding arm and application module (AMO). T1-weighted fast low angle shot (FLASH) 2-D-GRE sequence (TR/TE=110/4 ms) and T2-weighted turbo spin-echo (TSE)-sequences (TR/TE=3200/97 ms) in transversal orientation were used for the monitoring of the punction of the prostate gland. Planning and control of the intervention is to be made outside the scanner room on a desktop computer that receives DICOM images from the scanner. Servopneumatic drives move the AMO to the insertion point. The physician has to introduce the punction needle manually. The mean deviation of the needle tip to the target in a gel phantom was 0.35 mm. An accurate punction of the prostate gland can easily be performed using this system with a transgluteal access. The T2-weighted images are superior for the evaluation of the prostate anatomy and the needle position during the interventions. In conclusion, our preliminary results indicate that this MR-guided assistance system is suitable for an accurate transgluteal needle placement in the prostate.     

MR-guided vacuum-assisted breast biopsy using a non-titanium needle

Biopsy is required for definitive diagnosis of lesions detected by magnetic resonance (MR) imaging that are suspicious or highly suggestive of malignancy. We performed MR-guided vacuum-assisted biopsy (VAB) using a commercially available biopsy device without a nonmagnetic needle in 5 patients with 5 lesions that were occult according to mammographic and sonographic findings. Complete removal was seen in 3 cases and partial removal in two. The VAB procedures were very well tolerated, and no important side effects were observed. MR-guided VAB can be performed safely with a nonmagnetic needle.     

Interactive MR-guided biopsies of maxillary and skull-base lesions in an open-MR system: first clinical results

The purpose of this study was to explore the potential of interactive MR-guided biopsies in the maxillary and skull base region using a 0.5-T open-configuration scanner in patients with tumours affecting the maxilla or skull base. Ten patients with cystic or solid tumours affecting the maxillary and skull base regions underwent MR-guided biopsy in a superconducting, open 0.5-T MR system equipped with an optical frameless stereotaxic system. T2-weighted spin-echo images were acquired prior to and following biopsy, which was performed with 18- or 22-G needles using an enoral or percutaneous approach following infiltration of the skin, mucosa and periosteum with local anaesthetics. The position of the needle tip was continuously updated on fast T1-weighted gradient-recalled-echo images (TR 19 ms, TE 7.1 ms, flip angle 30 °, slice thickness 1 cm, field of view 24 × 24 cm) using the frameless stereotaxic system. In addition, the needle was identified based on the associated susceptibility artefact in all three planes. Once the target lesion had been reached, cytology material was aspirated. All ten patients tolerated the interactive MR-guided biopsies well without complications. Vital structures, including the brain, neurovascular bundles, vessels and eyes, were visualized on MR imaging and could be spared. There was no difference in the use of 18- or 22-G non-ferromagnetic needles concerning the susceptibility artefact. Sufficient material for cytological analysis was obtained in nine of ten cases. The mean biopsy time was 15 min. Interactive MR-guided biopsies of the head and neck in an open system are technically feasible and safe. Monitoring of the needle path in multiple planes permits the interactive adjustment of the needle course in near real time. Interactive MR-guided biopsies may well replace open surgical procedures in the maxillary region in selected patients. Received: 26 May 1998; Revision received: 18 August 1998; Accepted: 7 September 1998     

Prostate cancer transrectal HIFU ablation: detection of local recurrences using T2-weighted and dynamic contrast-enhanced MRI

The objective was to evaluate T2-weighted (T2w) and dynamic contrast-enhanced (DCE) MRI in detecting local cancer recurrences after prostate high-intensity focused ultrasound (HIFU) ablation. Fifty-nine patients with biochemical recurrence after prostate HIFU ablation underwent T2-weighted and DCE MRI before transrectal biopsy. For each patient, biopsies were performed by two operators: operator 1 (blinded to MR results) performed random and colour Doppler-guided biopsies (“routine biopsies”); operator 2 obtained up to three cores per suspicious lesion on MRI (“targeted biopsies”). Seventy-seven suspicious lesions were detected on DCE images (n?=?52), T2w images (n?=?2) or both (n?=?23). Forty patients and 41 MR lesions were positive at biopsy. Of the 36 remaining MR lesions, 20 contained viable benign glands. Targeted biopsy detected more cancers than routine biopsy (36 versus 27 patients, p?=?0.0523). The mean percentages of positive cores per patient and of tumour invasion of the cores were significantly higher for targeted biopsies (p?<?0.0001). The odds ratios of the probability of finding viable cancer and viable prostate tissue (benign or malignant) at targeted versus routine biopsy were respectively 3.35 (95% CI 3.05–3.64) and 1.38 (95% CI 1.13–1.63). MRI combining T2-weighted and DCE images is a promising method for guiding post-HIFU biopsy towards areas containing recurrent cancer and viable prostate tissue.     

Dynamic contrast-enhanced MR imaging and MR-guided bone biopsy on a 0.23T open imager

Objective:To assess the feasibility of MR-guided bone biopsies.Methods::Thirty-six consecutive patients with known or suspected benign or malignant bone lesions underwent comprehensive MR imaging.A dynamic contrast-enhanced sequence followed by stationary Ti-weighted sequences were obtained and MR-guided bone biopsy of the tumor at the site with fastest enhancement was performed using an open 0.23 T MR imager.Results:All MR-guided bone biopsies samples were estimated to be sufficient by the pathologists.The biopsy specimens were diagnostic in 34 of 36 cases.Conclusion:MR-guided bone biopsies combined with dynamic contrast-enhanced imaging are feasible and safe for the diagnostic investigation of equivocal bone lesions.     

MR-guided vacuum-assisted breast biopsy in the management of incidental enhancing lesions detected by breast MR imaging

Purpose

The objective of this study was to determine the clinical value and accuracy of magnetic resonance (MR)-guided vacuum-assisted breast biopsy (VAB).

Materials and methods

We retrospectively analysed 106 incidental breast lesions detected on MR imaging in 98 patients. Patients with nonpalpable suspicious lesions that were only MR visible were referred for MR-VAB performed with a 10-gauge needle. All patients with a VAB diagnosis of infiltrating carcinoma, carcinoma in situ or atypical epithelial hyperplasia were referred for surgery. Histopathology of the surgical specimen was considered the reference standard.

Results

MR-guided VAB was attempted in 29/106 lesions (27%); in 2/29 patients, the procedure could not be performed owing to failure to visualise the lesion. Lesions with clearly malignant features and borderline lesions (atypical ductal hyperplasias) were identified in 12 cases (44%) and benign entities in 15 (56%). Seven of 12 (58%) malignant lesions were <10 mm. Among the 27 successful MR-VAB procedures, VAB yielded one false-negative diagnosis (4%) and underestimation (4%). MR-guided VAB sensitivity and specificity were 92% and 100%, respectively, with a positive predictive value of 100% and a negative predictive value of 93%.

Conclusions

The results of this study indicate that MR-guided VAB offers good accuracy in characterising nonpalpable breast lesions visible on MR imaging alone. Small lesion size (<1 cm) did not prove to be a limitation for the success of the procedure.     

MR-guided vacuum-assisted breast biopsy with a handheld biopsy system: clinical experience and results in postinterventional MR mammography after 24 h

This prospective study evaluates the feasibility of the magnetic resonance (MR)-guided vacuum-assisted breast biopsy with a handheld vacuum-biopsy system and documents the biopsy results with MR mammography 24 h after the procedure. MR-guided biopsy was undertaken in 33 patients with 34 lesions on dynamic MR mammography. The interventions were performed with the handheld 10-gauge Vacora vacuum-biopsy system. In all cases, dynamic MR mammography was performed 24 h after the procedure to determine the extent of the lesion removal and to identify the lesions that were missed. In 5/34 (14.7%) lesions, biopsy was not performed because no suspicious lesion was identified on the day of biopsy. In 25/29 (86.2%) lesions, the biopsy was successfully performed with a complete removal in 4/29 (13.8%) and a partial removal of 21/29 (72.4%) lesions. In 4/29 (13.8%) interventions the lesion was missed with the biopsy. In one case, histopathology after surgical excision revealed ductal carcinoma in situ. Histopathology revealed 9/29 (31%) malignant and 20/29 (68.9%) benign lesions. MR-guided vacuum-assisted breast biopsy with the handheld Vacora vacuum-biopsy system is technically feasible in most cases. MR mammography 24 h after the biopsy should be performed in those cases in which the biopsy success is unclear immediately after the procedure.     

Real-time virtual sonography (RVS)-guided vacuum-assisted breast biopsy for lesions initially detected with breast MRI

Purpose

To report on our initial experiences with a new method of real-time virtual sonography (RVS)-guided 11-gauge vacuum-assisted breast biopsy for lesions that were initially detected with breast MRI.

Materials and methods

RVS-guided 11-gauge vacuum-assisted biopsy is performed when a lesion with suspicious characteristics is initially detected with breast MRI and is occult on mammography, sonography, and physical examination. Live sonographic images were co-registered to the previously loaded second-look spine contrast-enhanced breast MRI volume data to correlate the sonography and MR images.

Results

Six lesions were examined in six consecutive patients scheduled to undergo RVS-guided 11-gauge vacuum-assisted biopsy. One patient was removed from the study because of non-visualization of the lesion in the second-look spine contrast-enhanced breast MRI. Five patients with non-mass enhancement lesions were biopsied. The lesions ranged in size from 9 to 13 mm (mean 11 mm). The average procedural time, including the sonography and MR image co-registration time, was 25 min. All biopsies resulted in tissue retrieval. One was fibroadenomatous nodules, and those of four were fibrocystic changes. There were no complications during or after the procedures.

Conclusion

RVS-guided 11-gauge vacuum-assisted breast biopsies provide a safe and effective method for the examination of suspicious lesions initially detected with MRI.     

MR-guided intervention in women with a family history of breast cancer

OBJECTIVE: A study was undertaken to assess the clinical value of magnetic resonance (MR) imaging-guided interventions in women with a family history, but no personal history of breast cancer. METHODS AND PATIENTS: Retrospective review was performed on 63 consecutive women who had a family history, but no personal history of breast cancer. A total of 97 lesions were referred for an MR-guided intervention. Standardized MR examinations (1.0 T, T1-weighted 3D FLASH, 0.15 mmolGd-DTPA/kg body weight, prone position) were performed using a dedicated system which allows vacuum assisted breast biopsy or wire localization. RESULTS: Histologic findings in 87 procedures revealed 9 (10%) invasive carcinomas, 12 (14%) ductal carcinomas in situ, 2 atypical ductal hyperplasias (2.5%) and 2 atypical lobular hyperplasias (2.5%). Sixty-two (71%) benign histologic results are verified by an MR-guided intervention, retrospective correlation of imaging and histology and by subsequent follow-up. In ten lesions the indication dropped since the enhancing lesion was no longer visible. Absent enhancement was confirmed by short-term re-imaging of the noncompressed breast and by follow-up. CONCLUSION: Malignancy was found in 24%, high-risk lesions in 5% of successfully performed MR-guided biopsy procedures. A 57% of MR-detected malignancies were ductal carcinoma in situ. In 10% of the lesions the intervention was not performed, since no enhancing lesion could be reproduced at the date of anticipated intervention. Such problems may be avoided if the initial MRI is performed in the appropriate phase of the menstrual cycle and without hormonal replacement therapy.     

Adrenal masses: characterization with T1-weighted MR imaging

The ability of a T1-weighted spin-echo magnetic resonance (MR) sequence to allow differentiation of benign from malignant adrenal masses at 0.5 T was investigated in 28 patients with 35 adrenal masses. All nine lesions with an adrenal mass-liver signal intensity ratio of 0.71 or less were metastases, and all 15 with a ratio of 0.78 or more were adenomas. Eleven masses (31%)--including six adenomas, three metastases, a pheochromocytoma, and a neuroblastoma--had ratios between these values. Nine of ten masses with adrenal mass-fat intensity ratios of 0.35 or less were metastases, and all 12 with ratios of 0.42 or more were benign. Eleven masses (31%), four malignant and one benign, had ratios between these values. The ratios for two masses could not be calculated due to lack of fat. The specificity of T1-weighted MR imaging in differentiating benign from malignant adrenal masses appears similar to that reported for T2-weighted imaging. However, significant overlap occurred, as has also been reported for T2-weighted imaging. While both imaging sequences may help distinguish benign from malignant adrenal masses in some cases, biopsy is still necessary when an accurate histologic diagnosis is essential.     

MR imaging-guided prostate biopsy with a closed MR unit at 1.5 T: initial results

The authors evaluated a magnetic resonance (MR) imaging-compatible biopsy device comprising a needle guide that can be visualized with MR imaging and manipulated mechanically from outside the MR unit. With approval from the local ethics committee and patient consent, this device was tested in 12 patients by using a closed 1.5-T MR unit and a body phased-array coil. Patients had elevated prostate-specific antigen levels (6-60 ng/mL) and one or more areas in the prostate that were suspicious for carcinoma at prebiopsy MR imaging. Biopsy was performed with transrectal access and with the patient prone. A 16-gauge MR imaging-compatible needle was successfully positioned with the device, and between six and nine tissue cores were obtained in each patient. In one patient, two suspicious basal areas could not be reached with the device. Histologic analysis showed prostate cancer in five patients and prostatitis in six. No complications were observed. The device enabled MR imaging-guided core-needle biopsy of prostate areas suspicious for cancer on MR images.     

Magnetic resonance of the prostate: critical evaluation of diagnostic possibilities

The authors retrospectively reviewed 140 MR examinations of the prostate to assess the presence of similar findings in the different patients affected with the same prostatic disease. In 35 patients with acute phlogosis, MR imaging showed enlargement of peripheral gland, with increased signal intensity on T2-weighted images, while reduced peripheral gland with low signal intensity was demonstrated in chronic phlogosis. Five patients presented roundish cystic lesions, with clear-cut outlines, clearly distinguishable from the surrounding parenchyma. Benign Prostatic Hyperplasia (BPH) was observed in 32 cases. 52% of them had multiple nodules with high signal intensity, 40% had hyperintense enlarged central glands, with no evidence of BPH nodules, and the remaining 8% presented single/multiple nodules with low signal intensity. In 56 patients with prostatic carcinoma the tumor extent ranged from 18-20 mm nodules to 5-6 cm masses with involvement of periprostatic adipose tissue or surrounding organs. The smallest lesions were always found in the peripheral gland and had low signal intensity on T2-weighted sequences. In spite of the different findings in the patients affected with BPH, the study proved MR imaging to be able to distinguish the various patterns of the different prostatic diseases.     

Follow-up of breast lesions detected by MRI not biopsied due to absent enhancement of contrast medium

Our objective was to follow-up patients in whom scheduled MR-guided vacuum biopsies for suspicious lesions were aborted due to absent enhancement of contrast medium. Thirty-seven of 291 scheduled MR-guided vacuum biopsies were aborted. Six cases were lost to follow-up. Two could be unequivocally identified and were nevertheless biopsied. In 25 of 29 patients absent enhancement was confirmed on subsequent studies without compression. Varying hormonal or inflammatory changes between initial MRI and MR-guided vacuum biopsy most probably explain the findings. Enhancement re-appeared on short-term follow-up <6 months without compression in 4 of the 29 patients. Too strong compression during MR-guided vacuum biopsy explains the absence of enhancement in these patients. Of note, on histology, three of these cases proved malignant. We conclude that short-term follow-up without compression is necessary and recommended for all lesions not visible during scheduled MR-guided vacuum biopsy. Electronic Publication