MR Imaging Guided Percutaneous Nephrostomy using a 1.0 Tesla Open MR Scanner

Ultrasound contrast agent assisted ultrasonography guidance percutaneous nephrostomy for non-hydronephrotic kidney

BACKGROUND

Given the limited success rate and considerable challenges associated with conventional ultrasonography (US) guidance for percutaneous nephrostomy (PCN) in non-hydronephrotic kidneys, this study proposed a solution with ultrasound contrast agent to enhance the success rate and mitigate the difficulties.

MATERIALS AND METHODS

From January 2017 to August 2023, a total of thirteen patients diagnosed with non-hydronephrotic kidney were included in the study. Following routine ultrasonography examination, no significant dilatation of the renal collecting system was observed. US-guided percutaneous nephrostomy PCN was performed with the assistance of ultrasound contrast agent (UCA). The patients were subsequently monitored to assess the improvement of symptoms and postoperative recovery.

RESULTS

The success rate was found to be 100% for all patients (13/13) and kidneys (20/20). The average volume of UCA solution used was 19 ± 6.7 mL (range, 11-35 mL), while the mean duration of the operation was 18.92 ± 8.96 min (range, 7-36 min). A majority of the patients (12/13) underwent a single puncture procedure. Throughout the follow-up period, no serious complications were observed, and surgery resulted in significant alleviation of symptoms in all patients.

CONCLUSION

The use of UCA-assisted US guidance PCN has been shown to be effective in achieving urinary diversion and alleviating associated clinical symptoms in non-hydronephrotic kidneys. In comparison to traditional methods, this approach demonstrates a high success rate and safety profile, while also offering a simplified operative procedure. Consequently, it presents a novel method and concept for managing non-hydronephrotic kidneys afflicted by urine leakage.

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.

Glass-Fiber-based MR-safe Guidewire for MR Imaging-guided Endovascular Interventions: In Vitro and Preclinical in Vivo Feasibility Study

Purpose To evaluate glass-fiber-based guidewires that are safe for magnetic resonance (MR) imaging-guided endovascular interventions by using a phantom and an in vivo swine model. Materials and Methods MR imaging-safe guidewires were made from micropultruded glass and/or aramid fibers and epoxy resin with diameters of 0.89 mm (0.035 inch) for standard and stiff guidewires and 0.36 mm (0.014 inch) for micro guidewires. MR imaging visibility and mechanical properties were assessed in a pulsatile flow model. After approval was obtained from the institutional animal care and use committee, MR imaging guidewires were evaluated for standard endovascular procedures in nine pigs. Real-time steady-state free-precession sequences were used for MR imaging-guided catheterization, balloon dilation, and stent implantation into aorto-iliac/visceral arteries and the vena cava (temporal resolution, five images per second; and spatial resolution, 150-mm field of view, and 128 × 128 matrix) with a 1.5-T clinical imager. Visualization with the guidewires was rated on a four-point scale, handling was rated on a three-point scale, and catheterization times for different vessel regions were determined by two interventional radiologists. Afterward, handling ratings and catheterization times were obtained for standard nitinol guidewires during x-ray-based fluoroscopy. Cannulation times, signal intensity in each vessel region, and visualization and handling ratings were measured for the MR imaging guidewires. Bland-Altman analysis was performed for inter- and intraobserver variability of cannulation time. Spearman rank correlation was used to compare handling of MR imaging guidewires and standard nitinol guidewires. Results MR imaging guidewires were characterized by good to excellent visibility, with a continuous artifact of 2 mm in diameter and 4 × 8-mm ball-shaped tip marker. Stiffness, flexibility, and guidance reflected comparable times for all in vitro and in vivo procedures with both the MR imaging and standard nitinol guidewires. Standard and micro MR imaging guidewires were most suitable for the iliac crossover maneuver. Phantom visceral artery cannulation was easier with standard and micro MR imaging guidewires. The stiff MR imaging guidewire provided the best support for cannulation of the swine aorta and vena cava. All interventional procedures were performed successfully without complications. Conclusion Preliminary results showed that the use of glass-fiber-based guidewires for evaluation of MR imaging-guided endovascular interventions is technically feasible and safe in a swine model, and potentially, in humans. ^© RSNA, 2017 Online supplemental material is available for this article.

Hybrid Approach for Biliary Interventions Employing MRI-Guided Bile Duct Puncture with Near-Real-Time Imaging

OBJECTIVE

To assess the feasibility of a hybrid approach employing MRI-guided bile duct (BD) puncture for subsequent fluoroscopy-guided biliary interventions in patients with non-dilated (≤3 mm) or dilated BD (≥3 mm) but unfavorable conditions for ultrasonography (US)-guided BD puncture.

METHODS

A total of 23 hybrid interventions were performed in 21 patients. Visualization of BD and puncture needles (PN) in the interventional MR images was rated on a 5-point Likert scale by two radiologists. Technical success, planning time, BD puncture time and positioning adjustments of the PN as well as technical success of the biliary intervention and complication rate were recorded.

RESULTS

Visualization even of third-order non-dilated BD and PN was rated excellent by both radiologists with good to excellent interrater agreement. MRI-guided BD puncture was successful in all cases. Planning and BD puncture times were 1:36 ± 2.13 (0:16-11:07) min. and 3:58 ± 2:35 (1:11-9:32) min. Positioning adjustments of the PN was necessary in two patients. Repeated capsular puncture was not necessary in any case. All biliary interventions were completed successfully without major complications.

CONCLUSION

A hybrid approach which employs MRI-guided BD puncture for subsequent fluoroscopy-guided biliary intervention is feasible in clinical routine and yields high technical success in patients with non-dilated BD and/or unfavorable conditions for US-guided puncture. Excellent visualization of BD and PN in near-real-time interventional MRI allows successful cannulation of the BD.

Feasibility and Usefulness of Intra-Cavitary Contrast-Enhanced Ultrasound in Percutaneous Nephrostomy

The aim of this study was to evaluate the feasibility and utility of intra-cavitary contrast enhanced ultrasound (ICCEUS) in guiding percutaneous nephrostomy (PCN) and assessing complications. Forty-five ultrasound-guided PCNs were performed in 35 patients with hydronephrosis resulting from urinary tract obstruction. Ultrasound contrast agent (0.1 mL diluted in 20-30 mL saline) was injected through the puncture needle and the drainage tube to precisely locate the device and obstruction, with the fluoroscopy results considered the gold standard. ICCEUS was performed again the next day to assess complications. All 45 PCNs were successfully performed under the guidance of ultrasound. With ICCEUS, we could confirm the correct insertion of needle and catheter and locate the obstruction in all 35 patients, with fluoroscopic results as the gold standard. Catheter dislodgement was diagnosed by administration of ultrasound contrast agent in 5 patients. Hematoma (1 patient) and urine leakage (1 patient) were also observed. With the advantages of lack of exposure to radiation, performance in real time and bedside availability, ICCEUS has the potential to become a new modality to guide PCN and assess catheter-related complications.

MR-guided percutaneous biopsy of solitary pulmonary lesions using a 1.0-T open high-field MRI scanner with respiratory gating

OBJECTIVES

To prospectively evaluate the feasibility, safety and accuracy of MR-guided percutaneous biopsy of solitary pulmonary lesions using a 1.0-T open MR scanner with respiratory gating.

METHODS

Sixty-five patients with 65 solitary pulmonary lesions underwent MR-guided percutaneous coaxial cutting needle biopsy using a 1.0-T open MR scanner with respiratory gating. Lesions were divided into two groups according to maximum lesion diameters: ≤2.0 cm (n = 31) and >2.0 cm (n = 34). The final diagnosis was established in surgery and subsequent histology. Diagnostic accuracy, sensitivity and specificity were compared between the groups using Fisher's exact test.

RESULTS

Accuracy, sensitivity and specificity of MRI-guided percutaneous pulmonary biopsy in diagnosing malignancy were 96.9 %, 96.4 % and 100 %, respectively. Accuracy, sensitivity and specificity were 96.8 %, 96.3 % and 100 % for lesions 2.0 cm or smaller and 97.1 %, 96.4 % and 100 %, respectively, for lesions larger than 2.0 cm. There was no significant difference between the two groups (P > 0.05). Biopsy-induced complications encountered were pneumothorax in 12.3 % (8/65) and haemoptysis in 4.6 % (3/65). There were no serious complications.

CONCLUSIONS

MRI-guided percutaneous biopsy using a 1.0-T open MR scanner with respiratory gating is an accurate and safe diagnostic technique in evaluation of pulmonary lesions.

KEY POINTS

• MRI-guided percutaneous lung biopsy using a 1.0-T open MR scanner is feasibility. • 96.9 % differentiation accuracy of malignant and benign lung lesions is possible. • No serious complications occurred in MRI-guided lung biopsy.

[Percutaneous interventions in an open MR system: technical background and clinical indications]

The latest and therefore more efficient open magnetic resonance (MR) scanners with a field strength of 1 T allow freehand fluoroscopic interventions with excellent image quality. Specifically designed interactive software simplifies examination planning and performance. Guidance in two imaging planes allows fast and accurate device positioning and interventional procedures during free breathing. The diagnostic and therapeutic spectrum includes a wide variety of interstitial percutaneous interventions. The most important are periradicular therapy (PRT), intra-abdominal drainage and nephrostoma placement, biopsies, especially in the breasts and liver and focal ablation therapy of malignant hepatic or renal lesions. As the approach is fast and robotic devices are not needed the method is increasingly being carried out in the clinical routine. A drawback of MR-guided interventions is the limitation in verbal communication during image acquisition. Furthermore, the portfolio of MR compatible instruments needs to be extended.

Radiation-free percutaneous nephrostomy performed on neonates, infants, and preschool-age children

AIM

The aim of this study was to evaluate the effectiveness and safety of high-frequency linear probe ultrasonographic (US) guidance percutaneous nephrostomy (PN) in terms of diagnostic and therapeutic approach in preschool-age children with urological problems.

MATERIALS AND METHODS

PN was performed on 40 kidneys in 33 patients (13 girls, 20 boys) aged 3 days - 7 years (mean 4.1 years). All procedures were performed with US guidance utilizing a Shimadzu SDU 2200 Xplus 5-10 mHz probe. Complete blood count, urinalysis, bladder urine culture, blood urea, and creatinine values were obtained before PN placement on the same day. Urine cultures were obtained by nephrostomy tube and compared to bladder urine culture.

RESULTS

PN procedures were technically successful in 39 kidney units (97.5%). Two major complications were macroscopic hematuria requiring blood transfusions (1 case) and sepsis (1 case). Minor complications were displacement of the catheter (4), urinary tract infection (4), urine extravasation (1), early dislocation of the catheter (1). In three cases, the catheter was replaced. Analysis of bladder urine showed that 13 patients (39.4%) had positive cultures, but analysis of PN urine showed that 25 patients (78.1%) had positive cultures.

CONCLUSIONS

PN is an easy, safe and efficient diagnostic and therapeutic procedure with few complications even in preschool-age children. The antibiotic regimen should be revised in order to avoid sepsis and urinary tract infection.

Effectiveness of ureteroscopy-assisted retrograde nephrostomy (UARN) for percutaneous nephrolithotomy (PCNL)

Objective

To determine the impact of ureteroscopy-assisted retrograde nephrostomy (UARN) during percutaneous nephrolithotomy (PCNL).

Materials and Methods

From April 2009 to September 2011, a total of 50 patients underwent PCNL for large renal stones (stone burden >2 cm). We performed UARN in the Galdakao-modified Valdivia position for 27 patients (UARN PCNL) and ultrasonography-assisted percutaneous nephrostomy in the prone position for 23 patients (prone PCNL).

Results

UARN PCNL significantly improved the stone-free rate (81.5% vs 52.2%) and the rate of residual stones (<4 mm, 92.6% vs 65.2%, P<0.05). The median length of the operation was significantly shorter for UARN PCNL, at 160 min, compared to 299 min for prone PCNL (P<0.001). There was one intraoperative complication in prone PCNL, namely a hemorrhage that resulted in stopping the initial treatment, but it was cured conservatively. The postoperative complications included a high grade fever that persisted for three days in two UARN PCNL patients (7.4%) and six prone PCNL patients (26.1%). The Clavien grading scores showed significantly lower postoperative complications for UARN PCNL compared to prone PCNL.

Conclusion

UARN is associated with a higher stone-free rate, shorter operation time, and fewer complications during PCNL than prone PCNL.