BACKGROUND: This study assessed the feasibility of acquiring single-attempt access to the pelvicalyceal system during percutaneous nephrolithotomy (PCNL) using stereotactic optical navigation combined with cone-beam CT (CBCT) imaging.
METHODS: Patients with a PCNL indication were prospectively included in this IRB approved study. After sterile preparation, fiducial markers were attached to patients\' skin. An initial intraprocedural CBCT scan was acquired, on which the urologist planned the needle trajectory using the navigation software. After verifying that no critical structures were crossed, the needle guide was aligned with the plan. A needle was manually inserted through the needle guide to the indicated depth and a second CBCT scan was performed for needle position confirmation. Both, scanning and needle insertion, were performed under apnea. The study evaluated technical success, accuracy, procedure time, complication rate, and radiation dose.
RESULTS: Between June 2022 and April 2023, seven patients were included. In all patients, the navigation system allowed safe puncture. However, the technical success rate was only 29%. In 42% of the cases, pelvicalyceal access was achieved by a small manual adjustment. In the remaining 29%, the needle was retracted and positioned per clinical standard. The average deviation between the needle and target was 5.9 ± 2.3 mm. The average total procedure time was 211 ± 44 min. The average radiation exposure was 6.4 mSv, with CBCT scanning contributing to 82% of this exposure.
CONCLUSIONS: The optical navigation system facilitated safe needle insertion but did not consistently ensure accurate one-attempt needle positioning for PCNL. Real-time visualization and trajectory correction may improve the technical success rate.

Microwave ablation (MWA) has gained relevance in the treatment of hepatic malignancies and especially in hepatocellular carcinoma (HCC), and it is an important alternative to surgery. The purpose of the study was to evaluate whether the minimal ablative margin (MAM) or the initial tumor size has a greater effect on the success of stereotactic MWA of HCC regarding the time to local tumor progression (LTP) and overall survival (OS).
88 patients, who received stereotactic MWA of 127 tumor lesions with a curative intention were included in this single-center, retrospective study. The MAM was evaluated in a side-by-side comparison of pre- and post-ablative, contrast-enhanced slice imaging. A Cox proportional hazard model with a frailty term was computed to assess the influence of the MAM and the maximum tumor diameter on the time to LTP and the OS.
The maximum tumor diameter was identified as a significant positive predictor for LTP (hazard ratio 1.04, 95% CI 1.00-1.08, p = 0.03), but it was not a significant positive predictor for the OS (p = 0.20). The MAM did not have a significant influence on LTP-free survival (p = 0.23) and OS (p = 0.67).
For the successful stereotactic MWA of HCC, the MAM and maximum tumor diameter might not have an influence on the OS, but the maximum tumor diameter seems to be an independent predictor of the time to LTP.

UNASSIGNED: Degenerative lumbar scoliosis is a prominent cause of adult spinal deformity with an increasing prevalence as the population ages. This pathology is associated with debilitating symptoms, including radicular back pain and lower extremity claudication. Surgical realignment of the spine and restoration of sagittal imbalance can reduce low back pain. Chronic sacroiliac dysfunction commonly causes low back radicular pain. We present a complicated case where stereotactic navigation facilitated an extensive fusion and decompression procedure for adult spinal deformity in an obese patient with multiple prior surgeries for scoliosis and sacroiliac joint pathology.
METHODS: A 69-year-old, obese female with scoliosis refractory to multiple interventions presented with severe, radicular lower back pain. On examination of the right lower extremity (RLE), she had mild weakness (3/5 strength) and reduced sensation to light touch over its anterolateral aspect (dermatome L4). She was unable to perform single leg stance or tandem walk. Imaging revealed moderate mid-lumbar levoscoliosis, severe degenerative disc disease and facet hypertrophy changes in the setting of prior multilevel lumbar fusion, and consecutive nerve root impingement between L1 and L5 (worst at L3-4). DEXA scan was consistent with osteoporosis. The patient underwent lumbar laminectomy with posterior fusion of T10-ilium, transforaminal lumbar interbody fusion, osteotomy, and decompression using stereotactic navigation. The presence of SI titanium dowels from her previous SI fusion procedure posed a challenge with respect to achieving pelvic fixation.
UNASSIGNED: Iliac screw placement is a critical adjunctive to lumbosacral fusion, notably for prevention of pseudoarthrosis; however, patients with prior SI fusion may present a biomechanical challenge to surgeons due to obstruction of the surgical site. The O-arm neuronavigation system was successfully used to bypass this obstruction and provide sacroiliac fixation in this procedure.
CONCLUSIONS: Stereotactic navigation (The O-arm Surgical Imaging System) can effectively be used to circumvent prior SI fusion in osteoporotic bone.

BACKGROUND: We carried out robot-assisted lateral pelvic lymph node dissection (LPLND) for rectal cancer with a stereotactic navigation system. The purpose of this study was to evaluate the accuracy and feasibility of the system.
METHODS: We constructed a navigation system based on the Polaris Spectra optical tracking device (Northern Digital Inc., Canada) and the open-source software 3D Slicer (version 3.8.1; http://www.slicer.org ). We used the landmark-based registration method for patient-to-image registration. Body surface landmarks and intra-abdominal landmarks were used. We evaluated the time required for registration and target registration error (TRE; the distance between corresponding points after registration) for the root of the superior gluteal artery the root of the obturator or superior vesical artery, and the obturator foramen during minimally invasive LPLND for rectal cancer. Five patients who had LPLND for rectal cancer at the University of Tokyo Hospital between September 2020 and May 2021 were enrolled.
RESULTS: The mean time required for registration was 49 s with the body surface landmarks and 88 s with the intra-abdominal landmarks. The mean TRE improved markedly when the registration was performed using intra-abdominal landmarks. The mean TRE of the root of the superior gluteal artery, the root of the obturator or superior vesical artery, and the obturator foramen were 55.8 mm, 53.4 mm, and 55.2 mm with the body surface landmarks and 11.8 mm, 10.0 mm, and 12.6 mm with the intra-abdominal landmarks, respectively. There were no adverse events related to the registration process.
CONCLUSIONS: When stereotactic navigation systems are used for minimally invasive LPLND, the use of intra-abdominal landmarks for registration is feasible and may allow simpler and more accurate navigation than the use of body surface landmarks.

OBJECTIVE: Stereotactic navigation is being increasingly used for orbital decompression (OD). Recent studies have cited clinical benefits of navigation including greater proptosis reduction but have differed regarding effects on operative time. This study aimed to evaluate navigated vs. non-navigated OD with respect to operative time and proptosis reduction.
METHODS: Retrospective nonrandomized comparative trial of navigated vs. nonnavigated OD. Operative time and proptosis reduction were recorded and analyzed for all patients.
RESULTS: A total of 30 orbital decompressions were included; 14 were performed with stereotactic navigation (SN), and 16 were performed without SN. On average, the SN group took 19 minutes longer for 3-wall decompressions (p = 0.185), 25 minutes shorter for balanced decompressions (p = 0.025), and 18 minutes longer (p = 0.067) for lateral wall decompressions. Mean proptosis reduction (PR) in 3-wall decompressions was greater in the SN group (p = 0.02). Among balanced wall decompressions, mean PR was 4.25 mm and 3.67 mm for the SN and non-SN groups (p = 0.30), respectively. For lateral wall decompressions, mean PR was 2.63 mm with SN and 2.50 mm without SN (p = 0.45).
CONCLUSIONS: This study showed no difference in operative times between navigated and non-navigated OD, although empirical experience showed variable times required for registration and intraoperative troubleshooting of the navigation system. This study also found that navigation increased proptosis reduction for all types of OD. Further randomized controlled trials are needed to better understand the impact of navigation technology on operative times and surgical outcomes.

Endoscopic fenestration is best as it is minimally invasive and does not require hardware in the surgical site (Figure 1). This case shows the safety of endoscopic fenestration and the utility of operative adjuncts (J Korean Med Sci. 1999;14:443; Neurosurg Focus. 2005;19:E7).

A 73-year-old woman presented with progressive symptoms of cranial nerve (V, VI, VIII) palsies, ataxia and gait disturbance due to a rapidly growing atypical trigeminocavernous mass. Percutaneous stereotactic transoval biopsy via Hartel\'s route revealed an exceedingly rare solitary trigeminal metastasis of a clear cell renal cell carcinoma, treated 16 years earlier without any other evidence of systemic disease. A minimally invasive, intra-operatively navigated approach is presented with detailed description of the stereotactic technique and technical considerations. The transoval biopsy expands the surgical repertoire for atypical Meckel cave lesions with diagnostic uncertainty. A frameless navigated technique should be state-of-the-art in contemporary neurosurgical practice.

Image-guided robotics for biopsy and ablation aims to minimize procedure times, reduce needle manipulations, radiation, and complications, and enable treatment of larger and more complex tumors, while facilitating standardization for more uniform and improved outcomes. Robotic navigation of needles enables standardized and uniform procedures which enhance reproducibility via real-time precision feedback, while avoiding radiation exposure to the operator. Robots can be integrated with computed tomography (CT), cone beam CT, magnetic resonance imaging, and ultrasound and through various techniques, including stereotaxy, table-mounted, floor-mounted, and patient-mounted robots. The history, challenges, solutions, and questions facing the field of interventional radiology (IR) and interventional oncology are reviewed, to enable responsible clinical adoption and value definition via ergonomics, workflows, business models, and outcome data. IR-integrated robotics is ready for broader adoption. The robots are coming!

Accurate stereotactic biopsies of brain tumors are imperative for diagnosis and tailoring of the therapy. Repetitive needle insertions enhance risks of brain lesioning, hemorrhage, and complications due to prolonged procedure.
To investigate clinical benefits of a combined 5-aminolaevulinic acid (5-ALA) fluorescence and laser Doppler flowmetry system for the detection of malignant brain tumor and blood vessels in stereotactic biopsies.
Planning of targets and trajectories was followed by optical measurements in 20 patients, using the Leksell Stereotactic System and a manual insertion device. Fluorescence spectra, microvascular blood flow, and tissue grayness were recorded each millimeter along the paths. Biopsies were taken at preplanned positions. The diagnoses were compared with the fluorescence signals. The recordings were plotted against measurement positions and compared. Sites indicating a risk of hemorrhage were counted as well as the time for the procedures.
Signals were recorded along 28 trajectories, and 78 biopsies were collected. The final diagnosis showed 17 glioblastomas, 2 lymphomas, and 1 astrocytoma grade III. Fluorescence was seen along 23 of the paths with 4 having the peak of 5-ALA fluorescence 3 mm or more from the precalculated target. There was increased microcirculation in 40 of 905 measured positions. The measurement time for each trajectory was 5 to 10 min.
The probe provided direct feedback of increased blood flow along the trajectory and of malignant tissue in the vicinity of the target. The method can increase the precision and the safety of the biopsy procedure and reduce time.

Electrochemotherapy (ECT) is a novel non-thermal ablative technique that combines chemotherapy and the application of electric pulses for reversible cell membrane electroporation. This method was recently performed in the treatment of deep-seated liver tumors during open surgery but experience about percutaneous ECT is rare and further developments like combination of percutaneous ECT with stereotactic navigated devices may be very promising. We report on a case of a 4.7 × 4.5 × 3.5 cm unresectable HCC at the hepatic hilum adjacent to the major vessels and the bile duct that was successfully treated using percutaneous ECT in combination with stereotactic navigation. Follow-up imaging 6 weeks and 6 months after ECT showed complete response.