Magnetic Resonance Imaging–Guided Percutaneous Biopsy of Mediastinal Masses: Diagnostic Performance and Safety

Efficacy of contrast-enhanced ultrasound-guided percutaneous core needle biopsy in anterior mediastinal masses

Objective

To evaluate the efficacy and safety of percutaneous core needle biopsy (PCNB) using ultrasound (US)-guided and contrast-enhanced ultrasound (CEUS)-guided procedures for anterior mediastinal masses (AMMs).

Methods

In total, 284 consecutive patients (166 men, 118 women; mean age, 43.0 ​± ​18.4 years) who underwent PCNB for AMMs were enrolled. Patients were divided into the US-guided group (n ​= ​133) and the CEUS-guided group (n ​= ​151). PCNB was performed using a core needle (16-gauge or 18-gauge). Internal necrosis, diagnostic yield, and diagnostic accuracy were compared between the two groups.

Results

The predominant final diagnosis of the cases in this study was thymoma (29.7%), lymphoma (20.5%), thymic carcinoma (13.3%), and germ cell tumour (13.3%), respectively. There was no significant difference in patient age, sex, number of percutaneous biopsies, or display rate of internal necrosis on conventional US between the two groups. The rate of internal necrosis of the lesions was significantly higher after contrast agent injection (72.2% vs. 41.7%; P ​< ​0.001). The CEUS-guided group had a higher diagnostic yield than the US-guided group (100% vs. 89.5%, P ​< ​0.001). There was no significant difference between the diagnostic accuracy of the CEUS-guided and US-guided groups (97.3% vs. 97.4%; P ​= ​1.000). None of the patients experienced adverse reactions or complications after US-guided or CEUS-guided PCNB.

Conclusions

CEUS-guided PCNB can improve the diagnostic yield by optimizing the biopsy procedure.

Magnetic Resonance Imaging for Guidance and Follow-up of Thoracic Needle Biopsies and Thermal Ablations

Magnetic resonance imaging (MRI) is used for the guidance and follow-up of percutaneous minimally invasive interventions in many body parts. In the thorax, computed tomography (CT) is currently the most used imaging modality for the guidance and follow-up of needle biopsies and thermal ablations. Compared with CT, MRI provides excellent soft tissue contrast, lacks ionizing radiation, and allows functional imaging. The role of MRI is limited in the thorax due to the low hydrogen proton density and many air-tissue interfaces of the lung, as well as respiratory and cardiac motion. Here, we review the current experience of MR-guided thoracic needle biopsies and of MR-guided thermal ablations targeting lesions in the lung, mediastinum, and the chest wall. We provide an overview of MR-compatible biopsy needles and ablation devices. We detail relevant MRI sequences and their relative advantages and disadvantages for procedural guidance, assessment of complications, and long-term follow-up. We compare the advantages and disadvantages of CT and MR for thoracic interventions and identify areas in need of improvement and additional research.

The Value of 3 Tesla Field Strength for Musculoskeletal Magnetic Resonance Imaging

ABSTRACT

Musculoskeletal magnetic resonance imaging (MRI) is a careful negotiation between spatial, temporal, and contrast resolution, which builds the foundation for diagnostic performance and value. Many aspects of musculoskeletal MRI can improve the image quality and increase the acquisition speed; however, 3.0-T field strength has the highest impact within the current diagnostic range. In addition to the favorable attributes of 3.0-T field strength translating into high temporal, spatial, and contrast resolution, many 3.0-T MRI systems yield additional gains through high-performance gradients systems and radiofrequency pulse transmission technology, advanced multichannel receiver technology, and high-end surface coils. Compared with 1.5 T, 3.0-T MRI systems yield approximately 2-fold higher signal-to-noise ratios, enabling 4 times faster data acquisition or double the matrix size. Clinically, 3.0-T field strength translates into markedly higher scan efficiency, better image quality, more accurate visualization of small anatomic structures and abnormalities, and the ability to offer high-end applications, such as quantitative MRI and magnetic resonance neurography. Challenges of 3.0-T MRI include higher magnetic susceptibility, chemical shift, dielectric effects, and higher radiofrequency energy deposition, which can be managed successfully. The higher total cost of ownership of 3.0-T MRI systems can be offset by shorter musculoskeletal MRI examinations, higher-quality examinations, and utilization of advanced MRI techniques, which then can achieve higher gains and value than lower field systems. We provide a practice-focused review of the value of 3.0-T field strength for musculoskeletal MRI, practical solutions to challenges, and illustrations of a wide spectrum of gainful clinical applications.

Computed tomography-guided lung biopsy: a randomized controlled trial of low-dose versus standard-dose protocol

OBJECTIVES

To assess the relative diagnostic utility of low- and standard-dose computed tomography (CT)-guided lung biopsy.

METHODS

In this single-center, single-blind, prospective, randomized controlled trial, patients were enrolled between November 2016 and June 2017. Enrolled study participants were randomly selected to undergo either low- or standard-dose CT-guided lung biopsy. Diagnostic accuracy was the primary study endpoint, whereas technical success, radiation dose, and associated complications were secondary study endpoints.

RESULTS

In total, 280 patients underwent study enrollment and randomization, with 271 (low-dose group, 135; standard-dose group, 136) receiving the assigned interventions. Both groups had a 100% technical success rate for CT-guided lung biopsy, and complication rates were similar between groups (p > 0.05). The mean dose-length product (36.0 ± 14.1 mGy cm vs. 361.8 ± 108.0 mGy cm, p < 0.001) and effective dose (0.5 ± 0.2 mSv vs. 5.1 ± 1.5 mSv, p < 0.001) were significantly reduced in the low-dose group participants. Sensitivity, specificity, and overall diagnostic accuracy rates in the low-dose group were 91.8%, 100%, and 94.6%, respectively, whereas in the standard-dose group, the corresponding values were 89.6%, 100%, and 92.4%, respectively. These results indicated that diagnostic performance did not differ significantly between the 2 groups. Using univariate and multivariate analyses, we found larger lesion size (p = 0.038) and procedure-related pneumothorax (p = 0.033) to both be independent predictors of diagnostic failure.

CONCLUSIONS

Our results demonstrate that low-dose CT-guided lung biopsy can yield comparable diagnostic accuracy to standard-dose CT guidance, while significantly reducing the radiation dose delivered to patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02971176 KEY POINTS: • Low-dose CT-guided lung biopsy is a safe and simple method for diagnosis of lung lesions. • Low-dose CT-guided lung biopsy can yield comparable diagnostic accuracy to standard-dose CT guidance. • Low-dose CT-guided lung biopsy can achieve a 90% reduction in radiation exposure when compared with standard-dose CT guidance.

Percutaneous needle biopsy of mediastinal masses under C-arm conebeam CT guidance: diagnostic performance and safety

The aim of this study is to evaluate the feasibility of percutaneous needle biopsy of mediastinal masses under conebeam computed tomography (CBCT) and "XperGuide" navigation guidance. From September 2013 to April 2016, 40 patients (25 men and 15 women; mean age 52.5 years; range 18.7-86.4 years) with 40 mediastinal masses underwent CBCT-/"XperGuide"-guided percutaneous needle biopsies. Technical success, sensibility, specificity, positive predictive value (ppv), negative predictive value (npv) and complications rate were evaluated. Technical success evaluated as the correct positioning of the needle inside the lesion was 100%. Based on histopathological diagnosis, 2 of 40 biopsies (5%) resulted a false negative. Diagnostic accuracy was 95%, sensitivity was 95%, specificity was 100%, ppv was 100%, and npv was 33%. The mean total procedure time was 32 min (range 15-60 min) revealing a reduction in time comparing the first group of 20 patients (mean time 45 min) with the last group of 20 patients (mean time 17 min). No major complications were recorded. Only three patients (7.5%) had mild pneumothorax as demonstrated by post-procedural CBCT, resolved spontaneously. CBCT/"XperGuide" navigation system is a new, safe and accurate technique that can be used as guidance for mediastinal mass biopsies. It also permits the use of CT machines for diagnostic examinations relieving them from interventional procedures burden.

Assessment of a needle-tracking system for bipolar radiofrequency ablation

PURPOSE

The purpose of this study was to assess the accuracy and efficacy of a needle-tracking system in phantom and clinical studies using bipolar electrodes.

METHODS

To observe the tip of the electrode, a needle-tracking system with a volume navigation system was used. In the phantom study, the electrode was inserted at various angles and the error was verified. In the clinical study, 21 nodules close to extrahepatic organs or major vessels were enrolled between May and October 2014. After puncturing with the needle-tracking system, computed tomography (CT) was performed. The distances between the electrode tip and extrahepatic organs or major vessels were measured on both B-mode ultrasound (US) and CT. By comparing these distances, the accuracy of this system was evaluated.

RESULTS

In the phantom study, the deviation between the tip of the electrode and the virtual tip of the electrode was analyzed. The median values were within 2 mm at each puncture angle. In the clinical study, the difference between B-mode US and CT was less (mean value 1.17 ± 1.76 mm; range 0-3.5 mm).

CONCLUSION

The needle-tracking system is an accurate and useful system for bipolar radiofrequency ablation.

MRI-Guided Percutaneous Biopsy of Mediastinal Masses Using a Large Bore Magnet: Technical Feasibility

OBJECTIVE

To evaluate the diagnostic accuracy and safety of magnetic resonance imaging (MRI)-guided percutaneous biopsy of mediastinal masses performed using a wide-bore high-field scanner.

MATERIALS AND METHODS

This is a retrospective study of 16 consecutive patients (8 male, 8 female; mean age 74 years) who underwent MRI-guided core needle biopsy of a mediastinal mass between February 2010 and January 2014. Size and location of lesion, approach taken, time for needle placement, overall duration of procedure, and post-procedural complications were evaluated. Technical success rates and correlation with surgical pathology (where available) were assessed.

RESULTS

Target lesions were located in the anterior (n = 13), middle (n = 2), and posterior mediastinum (n = 1), respectively. Mean size was 7.2 cm (range 3.6-11 cm). Average time for needle placement was 9.4 min (range 3-18 min); average duration of entire procedure was 42 min (range 27-62 min). 2-5 core samples were obtained from each lesion (mean 2.6). Technical success rate was 100%, with specimens successfully obtained in all 16 patients. There were no immediate complications. Histopathology revealed malignancy in 12 cases (4 of which were surgically confirmed), benign lesions in 3 cases (1 of which was false negative following surgical resection), and one inconclusive specimen (treated as inaccurate since repeat CT-guided biopsy demonstrated thymic hyperplasia). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in our study were 92.3, 100, 100, 66.7, and 87.5%, respectively.

CONCLUSION

MRI-guided mediastinal biopsy is a safe procedure with high diagnostic accuracy, which may offer a non-ionizing alternative to CT guidance.