A practical guide for planning pelvic bone percutaneous interventions (biopsy, tumour ablation and cementoplasty)

Design and 3D printing of pelvis phantoms for cementoplasty

BACKGROUND

Percutaneous image-guided cementoplasty is a medical procedure for strengthening bones structurally altered by disease, such as osteolytic metastasis. This procedure involves injecting biocompatible liquid bone cement, through one or more trocars into the damaged bone. Within a few minutes the bone cement hardens and restores the rigidity of the bony structure. The introduction of this technique in the case of large cancellous bones, such as the pelvis, raises some practical issues such as: how to manage the flow of cement with variable viscosity over time and how to inject a large amount of cement under fluoroscopy to effectively restore the patient's ability to bear weight?

PURPOSE

As a means of training for young practitioners to ensure maximal filling of a metastatic bone area, we have designed and manufactured a pelvic phantom capable of replicating cement diffusion in healthy and metastatic bone under fluoroscopic and computed tomography guidance.

METHODS

The preliminary stage of the study consisted of an analysis of various lattice structures, with the objective of reproducing the haptic feedback experienced during the needle insertion and diffusion of cement within the trabecular bone. Cementoplasty tests were conducted by an experienced radiologist under fluoroscopy and CT guidance to evaluate the performance of the lattice structure. The initial analysis provided the groundwork for the design of the phantom pelvis, which was then evaluated against a patient case. The phantom was divided into two distinct components: a disposable section with lattice structure, intended for the injection of cement, and a reusable part representing the pelvic bones. Two additive manufacturing methods were selected for the production of the phantom: Stereolithography (SLA) for the lattice structure and Fused Deposition Modeling (FDM) for the pelvic bones. The disposable component was composed of different lattice structures, selected to best match the anatomic conditions of both healthy and diseased areas visible on the patient images. Subsequently, the performance of the phantom was validated against patient images through a cementoplasty test.

RESULTS

A total of 12 distinct lattice structures were subjected to three tests of cementoplasty. Stochastic lattices with 500 microns beam thickness and densities varying from 15% to 5% demonstrated the most effective replication of the needle haptic feedback, as well as the diffusion of the cement into healthy and osteolytic cancellous bone. These structures were then implanted in the phantom and validated against one patient case.

CONCLUSIONS

A methodology to design and manufacture a phantom dedicated to cementoplasty from patient images is proposed. Initially, a series of lattice structures, exhibiting diverse structure types, thicknesses, and densities, were evaluated to assess their capacity to accurately reproduce the haptic feedback of the needle and the diffusion of cement in the trabecular bone. Subsequent to the outcomes of these investigations, several structures were selected for the development of a phantom capable of accurately replicating a cementoplasty procedure under fluoroscopy and CT guidance. This phantom will enable the training of future practitioners on the procedure of cementoplasty in the pelvis.

Bone Biopsies: Practical Considerations and Technical Tips

Percutaneous image-guided needle biopsies are a safe and minimally invasive method of obtaining tissue of bone lesions. Radiologists are an integral part of a multidisciplinary team (MDT) approach to patient care in obtaining tissue for both pathologic diagnosis and advanced genetic/molecular testing. By utilizing image guidance, radiologists can target bone lesions with a very low complication rate. This review will discuss our approach to image-guided biopsies of bone lesions. Radiologists should be familiar with patient selection and imaging workup prior to performing biopsies, as well as the importance of coordinating the biopsy approach and sampling with the patient's clinical team. Management of bleeding and thrombotic risk in patients undergoing bone biopsies is also an important preprocedural consideration and will be discussed. The majority of bone biopsies are performed utilizing moderate sedation for patient analgesia and comfort, but close attention should be paid to patient comorbidities and potential interacting medications. Although computed tomography guidance remains the mainstay of image-guided biopsy, there are some circumstances in which ultrasound or fluoroscopic guidance may be beneficial. New advances in powered drill technology have made tissue sampling of bone lesions particularly sclerotic bone lesions both safer and faster with increased tissue yield. Finally, we will discuss image-guided biopsy of difficult anatomic regions that require special techniques to yield tissue safely.

Clinical efficacy and safety of microwave ablation combined with percutaneous osteoplasty for palliative treatment in pelvic osteolytic metastases

OBJECTIVES

To evaluate the impact of microwave ablation (MWA) on pain relief, quality of life, mobility, and local tumour progression in adult patients with pelvic osteolytic bone metastasis and to test the safety of MWA.

METHODS

This study retrospectively analysed the data from 20 patients with pelvic osteolytic metastases who received MWA combined with percutaneous osteoplasty (POP). The visual analogue scale (VAS), musculoskeletal tumour society system (MSTS), and Quality of Life Questionnaire-Bone Metastases 22 (QLQ-BM22) were used to evaluate the pain, limb function, and quality of life. The intraoperative and postoperative complications were recorded. The tumour recurrence and survival time were analysed during the follow-up period (range 3-26 months).

RESULTS

All (n = 20) MWA and POP operations were completed successfully. Four patients (20%; 95% CI, 6%-44%) had mild bone cement leakage from surrounding tissues, and there were no obvious symptoms or serious complications. There were significant differences in VAS, MSTS, and QLQ-BM22 scores before and after the operation (P < .001). During the postoperative follow-up period, 9 patients died. The median survival time was 8 months (range 3-26 months; IQR: 4.5-13; 95% CI, 4.2-15.3 months), and the 1-year survival rate was 65% (13/20; 95% CI, 41%-85%). Tumour recurrence occurred in 4 cases (20%; 95% CI, 6%-44%) after the operation, and the median time of recurrence was 12 months (range 8-16 months; IQR: 8.25-12.75; 95% CI, 5.5-18.5 months).

CONCLUSIONS

MWA combined with POP is an effective and safe treatment for pelvic osteolytic metastases. It can significantly relieve local pain, reconstruct limb function, improve patients' quality of life, and effectively control local tumour progression.

ADVANCES IN KNOWLEDGE

So far, the experience of using microwave in the treatment of pelvic metastases is still limited. MWA combined with POP in the treatment of pelvic osteolytic metastases can provide significant clinical benefits in acceptable low-risk minimally invasive situations and should be provided to patients with appropriate pelvic metastases in a multidisciplinary approach.

Percutaneous spine biopsy: reaching those hard-to-reach places

Cancer is a leading cause of death, with the spine being the most common site for skeletal metastasis. The spine is also a site for primary malignancy, such as sarcoma and chordoma, as well as non-neoplastic pathologies. An accurate diagnosis of spinal neoplastic diseases is crucial in determining appropriate management. With the advent of personalised oncology, the need to establish a definitive histopathologic diagnosis to guide management is more important than ever. Percutaneous biopsy has proven to be safe and efficient in establishing a reliable histopathologic diagnosis. The spine, however, can be a challenging site to biopsy, due to the proximity of critical neurovascular, respiratory, and gastrointestinal structures. Successful spine biopsy depends on several factors: suspected diagnosis, size of the lesion, location within the spine, modality for best imaging guidance, operator experience, technical equipment considerations, and desired approach and associated limitations. The specimen must also be obtained with a biopsy route amenable to any future surgical intervention, with surgical input often sought, frequently in a multidisciplinary setting, to confirm procedure-specific goals and expectations. Knowledge of the requisite local anatomy, procedural and patient-specific indications, and contraindications and various approaches that may be used to access different segments of the spine, potential complications, and how to address these are keys to a successful percutaneous spinal biopsy, even in the most challenging of circumstances.

Management of the kidney transplant patient with Cancer: Report from a Multidisciplinary Consensus Conference

INTRODUCTION

Cancer is the second most common cause of mortality and morbidity in Kidney Transplant Recipients (KTRs). Immunosuppression can influence the efficacy of cancer treatment and modification of the immunosuppressive regimen may restore anti-neoplastic immune responses improving oncologic prognosis. However, patients and transplant physicians are usually reluctant to modify immunosuppression, fearing rejection and potential graft loss. Due to the lack of extensive and recognised data supporting how to manage the immunosuppressive therapy in KTRs, in the context of immunotherapy, chemotherapy, radiotherapy and loco-regional treatments, a Consensus Conference was organised under the auspices of the European Society of Organ Transplantation and the Italian Society of Organ Transplantation. The conference involved a multidisciplinary group of transplant experts in the field across Europe.

METHODS

The overall process included a) the formulation of 12 specific questions based on the PICO methodology, b) systematic literature review and summary for experts for each question, c) a two-day conference celebration and the collection of experts' agreements. The conference was articulated in three sessions: "Immunosuppressive therapy and immunotherapy", "Systemic therapy", "Integrated Therapy", while the final experts' agreement was collected with a televoting procedure and defined according to the majority criterion.

RESULTS

Twenty-six European experts attended the conference and expressed their vote. A total of 14 statements were finally elaborated and voted. Strong agreement was found for ten statements, moderate agreement for two, moderate disagreement for one and uncertainty for the last one.

CONCLUSIONS

The consensus statements provide guidance to transplant physicians caring for kidney transplant recipients with cancer and indicate key aspects that need to be addressed by future clinical research.

Development of a fluoroscopically guided robotic assistant for instrument placement in pelvic trauma surgery

Purpose: A method for fluoroscopic guidance of a robotic assistant is presented for instrument placement in pelvic trauma surgery. The solution uses fluoroscopic images acquired in standard clinical workflow and helps avoid repeat fluoroscopy commonly performed during implant guidance. Approach: Images acquired from a mobile C-arm are used to perform 3D-2D registration of both the patient (via patient CT) and the robot (via CAD model of a surgical instrument attached to its end effector, e.g; a drill guide), guiding the robot to target trajectories defined in the patient CT. The proposed approach avoids C-arm gantry motion, instead manipulating the robot to acquire disparate views of the instrument. Phantom and cadaver studies were performed to determine operating parameters and assess the accuracy of the proposed approach in aligning a standard drill guide instrument. Results: The proposed approach achieved average drill guide tip placement accuracy of 1.57 ± 0.47    mm and angular alignment of 0.35 ± 0.32    deg in phantom studies. The errors remained within 2 mm and 1 deg in cadaver experiments, comparable to the margins of errors provided by surgical trackers (but operating without the need for external tracking). Conclusions: By operating at a fixed fluoroscopic perspective and eliminating the need for encoded C-arm gantry movement, the proposed approach simplifies and expedites the registration of image-guided robotic assistants and can be used with simple, non-calibrated, non-encoded, and non-isocentric C-arm systems to accurately guide a robotic device in a manner that is compatible with the surgical workflow.

Review article: the current status of CT-guided needle biopsy of the spine

CT-guided percutaneous needle biopsy of the spine is a well-described technique for determining the nature of indeterminate vertebral lesions or establishing a diagnosis of spinal infection, the high diagnostic accuracy and the safety of the procedure having been extensively documented. The purpose of the current article is to review the literature to date on CT-guided spinal biopsy. Specifically, indications for spinal biopsy, techniques for optimising yield, detail of the approaches for various spinal levels which is dependent upon both the region within the spinal column and lesion location within the vertebra (body vs. neural arch), determinants of biopsy outcome and complications are covered. It is hoped that the review will be of particular benefit to junior radiologists who are required to perform this procedure.

Fluoroscopic Guidance of a Surgical Robot: Pre-clinical Evaluation in Pelvic Guidewire Placement

PURPOSE

A method and prototype for a fluoroscopically-guided surgical robot is reported for assisting pelvic fracture fixation. The approach extends the compatibility of existing guidance methods with C-arms that are in mainstream use (without prior geometric calibration) using an online calibration of the C-arm geometry automated via registration to patient anatomy. We report the first preclinical studies of this method in cadaver for evaluation of geometric accuracy.

METHODS

The robot is placed over the patient within the imaging field-of-view and radiographs are acquired as the robot rotates an attached instrument. The radiographs are then used to perform an online geometric calibration via 3D-2D image registration, which solves for the intrinsic and extrinsic parameters of the C-arm imaging system with respect to the patient. The solved projective geometry is then be used to register the robot to the patient and drive the robot to planned trajectories. This method is applied to a robotic system consisting of a drill guide instrument for guidewire placement and evaluated in experiments using a cadaver specimen.

RESULTS

Robotic drill guide alignment to trajectories defined in the cadaver pelvis were accurate within 2 mm and 1° (on average) using the calibration-free approach. Conformance of trajectories within bone corridors was confirmed in cadaver by extrapolating the aligned drill guide trajectory into the cadaver pelvis.

CONCLUSION

This study demonstrates the accuracy of image-guided robotic positioning without prior calibration of the C-arm gantry, facilitating the use of surgical robots with simpler imaging devices that cannot establish or maintain an offline calibration. Future work includes testing of the system in a clinical setting with trained orthopaedic surgeons and residents.

Percutaneous image-guided double oblique anterior approach to the acetabulum for cementoplasty

AIM

To report the technique of percutaneous double oblique anterior access to the acetabulum and evaluate its feasibility and safety.

MATERIALS AND METHODS

Pelvic computed tomography (CT) examinations of 60 patients (30 men and 30 women; mean age 62.6±13.2 years) were retrieved randomly from the picture archiving and communication system (PACS). A virtual intraosseous trajectory was defined on both sides on the axial CT images with the entry point marked 1 cm above the anterosuperior iliac spine and the endpoint defined just above the level of the ischial spine at the midpoint of the posterior acetabulum. Patient age, sagittal oblique angulation, axial oblique angulation, length of intraosseous trajectory, distance from the hip joint, thickness of the iliac bone cortex, and intervening structure(s) between the skin and the bone entry points were recorded.

RESULTS

The mean sagittal and axial oblique angulations were 34.2±4.5° and 31.5±6.7°, respectively, and mean length of the intraosseous trajectory was 11.8±0.9 cm. The axial oblique angle and length of the intraosseous trajectory were significantly lower in the female than the male population (p<0.05). None of the virtual trajectories traversed the hip joint. In 112/120 trajectories (93.3%), there were no cortical breaches in the iliac bones. In eight trajectories in four patients, the virtual trajectory crossed either the medial iliac cortex (4/120; 3.3%) or the medial iliac cortex and the iliacus muscle (4/120; 3.3%).

CONCLUSION

The anterosuperior iliac and ischial spines can be used safely and reliably as landmarks to perform the double oblique anterior approach.

Cementoplasty of pelvic bone metastases: systematic assessment of lesion filling and other factors that could affect the clinical outcomes

OBJECTIVES

To evaluate lesion filling and other factors that could affect the clinical outcomes of cementoplasty for pelvic bone metastases.

METHODS

We retrospectively reviewed the files of 40 patients treated for 44 pelvic bone metastases, collected the parameters related to patients (pain relief evaluated on a visual analog scale, subsequent fractures, and need for surgery), lesions (size, cortical breach score, fracture, soft-tissue extension), and cementoplasty procedures (number of needles, volume of cement, percentage of lesion filling, cement leaks, residual acetabular roof defect), and performed a statistical analysis.

RESULTS

The lesions were on average 43.2 mm in diameter and the mean cortical breach score was 2.5 out of 6, with a pathological fracture in 14 lesions. The number of needles inserted was one in 32 out of 44, two in 10 out of 44, and three in 2 out of 44. On average, the volume of cement injected per lesion was 10.3 ml and the filling was 54.8%. Mild or moderate asymptomatic cement leakage occurred in 20 lesions (45.5%). The mean pain score was 84.2 mm before the procedure (with no correlation with lesion size, cortical breach score or fracture) and 45.6 mm at follow-up. The pain relief of 38.6 mm was statistically significant (p < 0.001) and did not correlate with the filling percentage. There were no fractures of the treated lesions at a mean follow-up of 355 days.

CONCLUSIONS

Cementoplasty of pelvic bone metastases appears effective for providing pain relief and may prevent subsequent fractures. We were unable to demonstrate a correlation between the lesion filling and the degree of pain relief.

Percutaneous osteoplasty for the management of a humeral head metastasis: Two case reports

RATIONALE

Percutaneous osteoplasty (POP) has been proved effective to relieve pain in metastases of vertebral, pelvis, and femur. Nevertheless, there are few reports about the effectiveness of POP in the humeral head metastases. In this study, we described 2 patients with humeral head metastases treated with POP in our hospital.

PATIENT CONCERNS

Case 1 was a 79-year-old man with vertebral and right humeral head metastasis after radical surgery or and periods of chemotherapy for bladder cancer. He suffered constant severe back and right shoulder joint pain even if taking much non-steroidal anti-inflammatory drugs. Case 2 was a 59-year-old woman with vertebral and right humeral head metastasis from lung cancer. She received regular radiotherapy and took much painkillers to relieve pain. However, the pain could not be relieved any more after 1 month and severely affects sleeping and daily activities.

DIAGNOSIS

Both 2 patients were diagnosed as vertebral metastases and right proximal humeral head metastases.

INTERVENTIONS

POP was performed to treat the right humeral head metastases. Percutaneous vertebroplasty (PVP) was performed to treat vertebral metastases.

OUTCOMES

After surgery, the patients experienced significant decrease in pain and better motor function. Both patients did not suffer from pulmonary embolism, infection, nerve injury, and bone cement syndrome.

LESSONS

For the pain that cannot be relieved by radiotherapy and analgesic drugs, POP is a safe and beneficial minimally invasive procedure that provides immediate and substantial relief from pain for humerus head metastases.