Adrenal Biopsy under Wide-Bore MR Imaging Guidance

Clinical benefits of MRI-guided freehand biopsy of small focal liver lesions in comparison to CT guidance

OBJECTIVES

To compare clinical success, procedure time, and complication rates between MRI-guided and CT-guided real-time biopsies of small focal liver lesions (FLL) < 20 mm.

METHODS

A comparison of a prospectively collected MRI-guided cohort (n = 30) to a retrospectively collected CT-guided cohort (n = 147) was performed, in which patients underwent real-time biopsies of small FLL < 20 mm in a freehand technique. In both groups, clinical and periprocedural data, including clinical success, procedure time, and complication rates (classified according to CIRSE guidelines), were analyzed. Wilcoxon rank sum test, Pearson's chi-squared test, and Fisher's exact test were used for statistical analysis. Additionally, propensity score matching (PSM) was performed using the following criteria for direct matching: age, gender, presence of liver cirrhosis, liver lobe, lesion diameter, and skin-to-target distance.

RESULTS

The median FLL diameter in the MRI-guided cohort was significantly smaller compared to CT guidance (p < 0.001; 11.0 mm vs. 16.3 mm), while the skin-to-target distance was significantly longer (p < 0.001; 90.0 mm vs. 74.0 mm). MRI-guided procedures revealed significantly higher clinical success compared to CT guidance (p = 0.021; 97% vs. 79%) as well as lower complication rates (p = 0.047; 0% vs. 13%). Total procedure time was significantly longer in the MRI-guided cohort (p < 0.001; 38 min vs. 28 min). After PSM (n = 24/n = 38), MRI-guided procedures still revealed significantly higher clinical success compared to CT guidance (p = 0.039; 96% vs. 74%).

CONCLUSION

Despite the longer procedure time, freehand biopsy of small FLL < 20 mm under MR guidance can be considered superior to CT guidance because of its high clinical success and low complication rates.

CLINICAL RELEVANCE STATEMENT

Biopsy of small liver lesions is challenging due to the size and conspicuity of the lesions on native images. MRI offers higher soft tissue contrast, which translates into a higher success of obtaining enough tissue material with MRI compared to CT-guided biopsies.

KEY POINTS

• Image-guided biopsy of small focal liver lesions (FLL) is challenging due to inadequate visualization, leading to sampling errors and false-negative biopsies. • MRI-guided real-time biopsy of FLL < 20 mm revealed significantly higher clinical success (p = 0.021; 97% vs. 79%) and lower complication rates (p = 0.047; 0% vs. 13%) compared to CT guidance. • Although the procedure time is longer, MRI-guided biopsy can be considered superior for small FLL < 20 mm.

Percutaneous needle biopsy under 1.2 Tesla open MRI guidance

PURPOSE

To evaluate the feasibility of percutaneous needle biopsy using a 1.2 Tesla open magnetic resonance imaging (MRI) system, which has the highest field strength among the currently available open MRI systems.

MATERIALS AND METHODS

This single-center prospective study included 10 patients. The primary endpoint was the feasibility of biopsy needle insertion into a target lesion under 1.2 Tesla open MRI guidance. The secondary endpoints included adverse events, device failures, and success of tissue specimen acquisition. Biopsy was performed for targets in various organs using an MRI-compatible coaxial needle system consisting of a 16G introducer needle and 18G semi-automatic biopsy needle. A newly developed body coil with a suitable design for intervention was used for intraprocedural imaging.

RESULTS

Biopsy procedures were performed for six musculoskeletal masses, two retroperitoneal masses, one renal mass, and one liver mass. The median diameter of the targets was 4.9 cm (range 2.1-22.8 cm). MRI-guided biopsy needle insertion was feasible in all 10 patients. In total, four grade 1 adverse events (as per Common Terminology Criteria for Adverse Events version 4.0) occurred in three patients. Adequate biopsy specimens for pathological diagnosis were successfully obtained from all 10 patients.

CONCLUSION

Percutaneous needle biopsy using a 1.2 Tesla open MRI system was feasible for relatively large targets, especially in the musculoskeletal region.

Diagnostic accuracy and safety of percutaneous MRI-guided biopsy of solid renal masses: single-center results after 4.5 years

OBJECTIVES

To retrospectively evaluate diagnostic accuracy and complications of magnetic resonance imaging (MRI)-guided biopsy of radiologically indeterminate solid renal masses (RM).

METHODS

Electronic records of all consecutive patients undergoing MRI-guided biopsy of solid RM (using free-breathing T2-BLADE and BEAT-IRTTT sequences) between April 2014 and October 2018 were reviewed; 101 patients (69 men, 32 women; median age 68 years; range 32-76) were included. Patient and RM characteristics, procedural details/complications, pathologic diagnosis, and clinical management were recorded. Diagnostic accuracy was calculated on an intention-to-diagnose basis. Diagnostic yield was also evaluated. Multi-variable analysis was performed for variables with p < .20, including patient age/sex; RM size/location/contact with vascular pedicle, RENAL score, number and total length of biopsy samples, and biopsy tract embolization, to determine factors associated with diagnostic samples, diagnostic accuracy, and complications.

RESULTS

Median RM size was 2.4 cm (range 1-8.4 cm). There were 86 (85%; 95%CI 77-91%) diagnostic and 15 (15%; 95%CI 9-23%) non-diagnostic samples; 6/15 (40%) non-diagnostic biopsies were repeated with 50% malignancy rate. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 96% (95%CI 89-99%), 100% (95%CI 77-100%), 100% (95%CI 95-100%), 82% (95%CI 57-96%), and 97% (95%CI 90-99%), respectively. Primary and secondary diagnostic yields were 85% (95%CI 77-91%) and 91% (95%CI 84-96%), respectively. Seven (7%; 95%CI 1-10%) complications were observed. No tested variables were associated with diagnostic samples, diagnostic accuracy, or complications.

CONCLUSIONS

MRI-guided biopsy of solid RM is associated with high diagnostic accuracy and low complication rate. The technique might be helpful for inaccessible tumors.

KEY POINTS

• MRI-guided biopsy of radiologically indeterminate solid renal masses (RM) appears safe, with a low rate of minor self-limiting hemorrhagic complications. • Diagnostic accuracy and primary/secondary diagnostic yield are high and appear similar to reported estimates for US- and CT-guided RM biopsy. • MRI guidance may be particularly useful for RM with poor conspicuity on US and CT, for relatively inaccessible tumors (e.g., tumors requiring double-oblique steep-angled approaches), and for young patients or those with renal failure.

Safety of percutaneous renal cryoablation: an international multicentre experience from the EuRECA retrospective percutaneous database

OBJECTIVE

To investigate the safety profile of percutaneous cryoablation of renal tumours < 7 cm, utilising data extracted from an international multicentre registry.

MATERIALS AND METHODS

A retrospective review of all immediate and delayed complications from a multicentre database was performed and was categorised according to the Clavien-Dindo classification. Statistical analysis was performed for both overall complications (all Clavien-Dindo) and major complications (Clavien-Dindo 3 to 5). The following criteria were identified as potential predictive factors for complications: centre number, modality of image guidance, tumour size (≤ 4 cm vs. > 4 cm), number of tumours treated in the same session (1 vs. > 1) and tumour histology.

RESULTS

A total of 713 renal tumours underwent ablation in 647 individual sessions. In 596 of the cases, one tumour was treated; in the remaining 51 cases, several tumours were treated per session. Mean lesion size was 2.8 cm. Fifty-four complications (Clavien-Dindo 1 to 5) occurred as a result of the 647 procedures, corresponding to an overall complication rate of 8.3%. The most frequent complication was bleeding (3.2%), with 9 cases (1.4%) requiring subsequent treatment. The rate of major complication was 3.4%. The only statistically significant prognostic factor for a major complication was a tumour size > 4 cm.

CONCLUSION

Percutaneous renal cryoablation is associated with a low rate of complications. Tumours measuring more than 4 cm are associated with a higher risk of major complications.

KEY POINTS

• Percutaneous kidney cryoablation has a low rate of complications. • Bleeding is the most frequent complication. • A tumour size superior to 4 cm is a predictive factor of major complication.