2011 Mid-America Orthopaedic Association Dallas B. Phemister Physician in Training Award: Can musculoskeletal tumors be diagnosed with ultrasound fusion-guided biopsy?

The role of imaging in extremity sarcoma surgery

The surgical management of extremity bone and soft tissue sarcomas has evolved significantly over the last 50 years. The introduction and refinement of high-resolution cross-sectional imaging has allowed accurate assessment of anatomy and tumor extent, and in the current era more than 90% of patients can successfully undergo limb-salvage surgery. Advances in imaging have also revolutionized the clinician's ability to assess treatment response, detect metastatic disease, and perform intraoperative surgical navigation. This review summarizes the broad and essential role radiology plays in caring for sarcoma patients from diagnosis to post-treatment surveillance. Present evidence-based imaging paradigms are highlighted along with key future directions.

Ultrasound Fusion: Applications in Musculoskeletal Imaging

Ultrasound fusion is an established technique that pairs real time B-scan ultrasound (US) with other forms of cross-sectional imaging, including computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). Each of these imaging modalities has distinct advantages. CT provides superior anatomic resolution, with improved imaging of bone and calcified structures; MRI has superior contrast resolution; and PET provides physiologic information, identifying processes that are metabolically active (i.e., tumor, inflammatory conditions). However, these modalities are static. A key highlight of ultrasound is its capability of dynamic, real-time scanning. The ability to pair CT, MRI or PET with ultrasound can have significant advantages, both in diagnostic evaluation and when performing difficult or challenging image-guided interventions. Percutaneous interventions using ultrasound fusion have been described in the abdominal imaging literature; however, there have been very few musculoskeletal applications detailed in the literature. The purpose of this article is to review the basic concepts of real-time ultrasound fusion, and to detail, through the use of multiple case examples, its potential use as a safe and effective method for performing image-guided musculoskeletal interventions.

Ultrasound-Guided Percutaneous Bone Biopsy: Feasibility, Diagnostic Yield and Technical Notes

While nowadays, CT-guided bone biopsy represents the gold standard tool for histopathological and microbiological diagnosis of skeletal lesions, the role of US-guided bone biopsy has not yet been fully explored. US-guided biopsy offers several advantages, such as the absence of ionizing radiation, fast acquisition time, as well as good intra-lesional echo, and structural and vascular characterization. Despite that, a consensus in regard to its applications in bone neoplasms has not been established. Indeed CT-guided technique (or fluoroscopic ones) still represents the standard choice in clinical practice. This review article aims to review the literature data about US-guided bone biopsy, underlying clinical-radiological indications, advantages of the procedure and future perspectives. Bone lesions taking the best advantages of the US-guided biopsy are osteolytic, determining the erosion of the overlying bone cortex and/or with an extraosseous soft-tissue component. Indeed, osteolytic lesions with extra-skeletal soft-tissue involvement represent a clear indication for US-guided biopsy. Moreover, even lytic bone lesions with cortical thinning and/or cortical disruption, especially located in the extremities or pelvis, can be safely sampled with US guidance with very good diagnostic yield. US-guided bone biopsy is proven to be fast, effective and safe. Additionally, it offers real-time needle evaluation, an advantage when compared to CT-guided bone biopsy. In the current clinical settings, it seems relevant to select the exact eligibility criteria for this imaging guidance since the effectiveness can vary depending on the type of lesion and body site involved.

Technical Feasibility of Electromagnetic US/CT Fusion Imaging and Virtual Navigation in the Guidance of Spine Biopsies

PURPOSE

 To test the technical feasibility of electromagnetic computed tomography (CT) + ultrasound fusion (US)-guided bone biopsy of spinal lesions.

MATERIALS AND METHODS

 This retrospective study included 14 patients referred for biopsy of spinal bone lesions without cortical disruption or intervertebral disc infection. Lesions were located in the sacrum (n = 4), lumbar vertebral body (n = 7) or intervertebral disc (n = 3). Fusion technology matched a pre-procedure CT scan with real-time ultrasound. The first six procedures were performed under both standard CT and CT + US fusion guidance (group 1). In the last eight procedures, the needle was positioned under fusion imaging guidance alone, and CT was only used at the end of needle placement to confirm correct positioning (group 2). Additionally, we retrieved 8 patients (controls) with location-matched lesions as group 2, which were biopsied in the past with the standard CT-guided technique. The procedure duration and number of CT passes were recorded.

RESULTS

 Mean procedure duration and median CT pass number were significantly higher in group 1 vs. group 2 (45 ± 5 vs. 26 ± 3 minutes, p = 0.002 and 7; 5.25-8.75 vs. 3; 3-3.25, p = 0.001). In controls, the mean procedure duration was 47 ± 4 minutes (p = 0.001 vs. group 2; p = 0.696 vs. group 1) and the number of CT passes was 6.5 (5-8) (p = 0.001 vs. group 2; p = 0.427 vs. group 1). No complications occurred and all specimens were adequate overall. In one case in group 2, the needle position was modified according to CT assessment before specimen withdrawal.

CONCLUSION

 Electromagnetic CT+US fusion-guided bone biopsy of spinal lesions is feasible and safe. Compared to conventional CT guidance, it may reduce procedural time and the number of CT passes.

Ultrasound-guided Biopsy of Musculoskeletal Soft-tissue Tumors: Basic Principles, Usefulness and Limitations

The aim of this article is to provide a short review of the literature concerning the basic principles, usefulness and limitations of ultrasound-guided biopsy of musculoskeletal soft-tissue tumors, with particular focus on core needle biopsies. Musculoskeletal soft-tissue tumors represent a rare and complex group of heterogeneous lesions. Prompt diagnosis of these uncommon lesions can improve the outcome and increase the patient survival rate. A biopsy examination of soft-tissue tumors with imaging modalities is necessary in all cases of aggressive or undetermined lesions. Although fine needle aspiration can be helpful for the biopsy of certain tumor types, core needle biopsy is a standard procedure in most tertiary sarcoma centers. It has a high diagnostic accuracy, low complication rate and lower price in comparison to open biopsy, and can replace it in the majority of cases of soft-tissue tumor assessment. However, the examining physician has to be familiar with the technique, and the strengths and potential difficulties in performing ultrasound-guided biopsy, as well as possible solutions to obstacles. Several recently developed ultrasound techniques can be helpful and improve the outcome of imaging-guided biopsies of musculoskeletal lesions.

Role of Fusion Imaging in Image-Guided Thermal Ablations

Thermal ablation (TA) procedures are effective treatments for several kinds of cancers. In the recent years, several medical imaging advancements have improved the use of image-guided TA. Imaging technique plays a pivotal role in improving the ablation success, maximizing pre-procedure planning efficacy, intraprocedural targeting, post-procedure monitoring and assessing the achieved result. Fusion imaging (FI) techniques allow for information integration of different imaging modalities, improving all the ablation procedure steps. FI concedes exploitation of all imaging modalities’ strengths concurrently, eliminating or minimizing every single modality’s weaknesses. Our work aims to give an overview of FI, explain and analyze FI technical aspects and its clinical applications in ablation therapy and interventional oncology.

Ultrasound-Guided Biopsies of Bone Lesions Without Cortical Disruption Using Fusion Imaging and Needle Tracking: Proof of Concept

OBJECTIVE

To assess the technical feasibility and safety of combined fusion imaging and needle tracking under ultrasound guidance to target bone lesions without cortical disruption.

MATERIALS AND METHODS

Between January 2016 and March 2016, seven patients underwent US-guided biopsy of bone lesions without cortical disruption. Targeted bone lesions were measuring more than 1.5 cm with a thin cortex, a trans-osseous pathway not exceeding 2 cm and without any adjacent vulnerable structures. First three procedures were performed in the CT suite to aid the needle tracking where necessary (group 1), the remaining four procedures were performed in the US suite (group 2). In group 1, deviation from the real position of the bone trocar (estimated on CT) was compared to the virtual position (estimated on the fusion CT-US images). In both group, procedure data and histopathological results were collected, and compared to the suspected diagnosis and follow-up.

RESULTS

Mean procedure duration was 44 min. Total number of synchronisation points for combined fusion imaging were 3.3 on average. In group 1, mean deviation between the virtual and real CT coordinates was 5.3 mm on average. All biopsies yielded adequate quality analysable bone sample. Histopathological analysis revealed malignancy in three cases, non-specific inflammation in two cases, and normal bone in two cases. The four benign results were confirmed as true negative results. There were no immediate or post-procedural complications.

CONCLUSION

The use of combined fusion imaging and needle tracking ultrasound guidance to target bone lesions without cortical disruption seems technically feasible, provided the patient and lesion selection is appropriate.

Percutaneous guided biopsy for diagnosing suspected primary malignant bone tumors in pediatric patients: a safe, accurate, and cost-saving procedure

BACKGROUND

Percutaneous biopsy is the reference diagnostic procedure for adult musculoskeletal tumors. Its place in pediatrics is controversial and open biopsy remains recommended.

OBJECTIVE

To assess diagnostic performance and feasibility of percutaneous biopsy performed on children and young adults for suspected malignant bone tumors.

MATERIALS AND METHODS

We conducted a 5-year retrospective study including patients ≤21 years who underwent a bone biopsy for a suspected malignant bone tumor. We assessed diagnostic yield (percentage of analyzable biopsies), accuracy (percentage of accurate diagnoses among all analyzable biopsies) and efficacy (percentage of accurate diagnoses among all biopsies), costs, anesthetic requirements and sample availability for biomedical research. Patients diagnosed with an open biopsy were used to compare diagnostic performances, anesthetic requirements and costs.

RESULTS

We included 90 percutaneous and 27 open biopsies in 117 patients. For percutaneous biopsy, diagnostic yield was 95.5% (95% confidence interval [CI] 88.8-98.7%), accuracy was 96.2% (95% CI 86.8-99.5%) and efficacy was 89.3% (95% CI 78.1-96.0%). There was no statistical difference with open biopsy (Fisher exact test, P > 0.05). Mean costs were reduced with percutaneous biopsy: €1,937 (standard deviation [SD] €2,408) versus €6,362 (SD €5,033; Mann-Whitney, P < 0.0001). Thirty-two of the 48 (67%) patients included in clinical trials and diagnosed with percutaneous biopsy had suitable samples for ancillary analyses.

CONCLUSION

Percutaneous biopsy is a valid alternative to open biopsy for diagnosing pediatric and young adult primary malignant bone tumors.

The Potential Use of Ultrasound-Magnetic Resonance Imaging Fusion Applications in Musculoskeletal Intervention

We sought to assess the potential use of an application allowing real-time ultrasound spatial registration with previously acquired magnetic resonance imaging in musculoskeletal procedures. The ultrasound fusion application was used to perform a range of outpatient procedures including piriformis, sacroiliac joint, pudendal and intercostal nerve perineurial injections, hamstring-origin calcific tendonopathy barbotage, and 2 soft tissue biopsies at our institution in 2015. The application was used in a total of 7 procedures in 7 patients, all of which were technically successful. The ages of patients ranged from 19 to 86 years. Particular use of the fusion application compared to sonography alone was noted in the biopsy of certain soft tissue lesions and in perineurial therapeutic injections.

Is Ultrasound Fusion a Reasonable Replacement for Computed Tomography in Guiding Abdominal Interventions?

OBJECTIVES

To compare the diagnostic yield, complication rate, and procedure length of ultrasound fusion-guided liver biopsy to the diagnostic yield, complication rate, and procedure length of computed tomography (CT)-guided liver biopsy; to measure the average ionizing radiation dose that patients are exposed to during a typical CT-guided liver biopsy procedure; and to present relevant and interesting cases of ultrasound fusion-guided abdominal interventions to describe the efficacious use of the technology.

METHODS

A retrospective analysis of 63 patients who had image-guided liver biopsies performed at our institution was completed. Patient records were divided into 2 groups according to the type of image guidance used during the procedure (ultrasound fusion versus CT), and data were compared by the χ(2) test, Student t test, and Mann-Whitney U test.

RESULTS

The diagnostic yields and complication rates were not statistically significantly different between the modalities. The average procedure durations were significantly different: ultrasound fusion-guided biopsy, 31.63 minutes; compared to CT-guided biopsy, 61.67 minutes (P = .003).

CONCLUSIONS

Diagnostic yields and complication rates were comparable for ultrasound fusion and CT. However, the average procedure duration for an ultrasound fusion-guided liver biopsy was approximately half that of CT-guided liver biopsy, likely increasing both cost-effectiveness and patient satisfaction.

Fusion imaging for evaluation of deep infiltrating endometriosis: feasibility and preliminary results

OBJECTIVE

Magnetic resonance imaging (MRI) and ultrasound scanning complement each other in screening for and diagnosis of endometriosis. Fusion imaging, also known as real-time virtual sonography, is a new technique that uses magnetic navigation and computer software for the synchronized display of real-time ultrasound and multiplanar reconstructed MR images. Our aim was to evaluate the feasibility and ability of fusion imaging to assess the main anatomical sites of deep infiltrating endometriosis (DIE) in patients with suspected active endometriosis.

METHODS

This prospective study was conducted over a 1-month period in patients referred to a trained radiologist for an ultrasound-based evaluation for endometriosis. Patients with a prior pelvic MRI examination within the past year were offered fusion imaging, in addition to the standard evaluation. All MRI examinations were performed on a 1.5-T MRI machine equipped with a body phased-array coil. The MRI protocol included acquisition of at least two fast spin-echo T2-weighted orthogonal planes. The Digital Imaging Communications in Medicine dataset acquired at the time of the MRI examination was loaded into the fusion system and displayed together with the ultrasound image on the same monitor. The sets of images were then synchronized manually using one plane and one anatomical reference point. The ability of this combined image to identify and assess the main anatomical sites of pelvic endometriosis (uterosacral ligaments, posterior vaginal fornix, rectum, ureters and bladder) was evaluated and compared with that of standard B-mode ultrasound and MRI.

RESULTS

Over the study period, 100 patients were referred for ultrasound examination because of endometriosis. Among them were 20 patients (median age, 35 (range, 27-49) years) who had undergone MRI examination within the past year, with a median (range) time interval between MRI and ultrasound examination of 171 (1-350) days. All 20 patients consented to undergo additional evaluation by fusion imaging. However, in three (15%) cases, fusion imaging was not technically possible because of changes since the initial MRI examination resulting from either interval surgery (n = 2; 10%) or pregnancy (n = 1; 5%). Data acquisition, matching and fusion imaging were performed in under 10 min in each of the other 17 cases. The overall ability of each technique to identify and assess the main anatomical landmarks of endometriosis was as follows: uterosacral ligaments: ultrasound, 88% (30/34); MRI, 100% (34/34); fusion imaging, 100% (34/34); posterior vaginal fornix: ultrasound, 88% (30/34); MRI, 100% (34/34); fusion imaging, 100% (34/34); rectum: ultrasound, 100% (17/17); MRI, 82.3% (14/17); fusion imaging, 100% (17/17); ureters: ultrasound, 0%; MRI, 100% (34/34); fusion imaging, 100% (34/34); and bladder: ultrasound, 100%; MRI, 100%; fusion imaging, 100%.

CONCLUSION

Fusion imaging is feasible for the assessment of endometriotic lesions. Because it combines information from both ultrasound and MRI techniques, fusion imaging allows better identification of the main anatomical sites of DIE and has the potential to improve the performance of ultrasound and MRI examination.

Development of a hybrid magnetic resonance and ultrasound imaging system

A system which allows magnetic resonance (MR) and ultrasound (US) image data to be acquired simultaneously has been developed. B-mode and Doppler US were performed inside the bore of a clinical 1.5 T MRI scanner using a clinical 1-4 MHz US transducer with an 8-metre cable. Susceptibility artefacts and RF noise were introduced into MR images by the US imaging system. RF noise was minimised by using aluminium foil to shield the transducer. A study of MR and B-mode US image signal-to-noise ratio (SNR) as a function of transducer-phantom separation was performed using a gel phantom. This revealed that a 4 cm separation between the phantom surface and the transducer was sufficient to minimise the effect of the susceptibility artefact in MR images. MR-US imaging was demonstrated in vivo with the aid of a 2 mm VeroWhite 3D-printed spherical target placed over the thigh muscle of a rat. The target allowed single-point registration of MR and US images in the axial plane to be performed. The system was subsequently demonstrated as a tool for the targeting and visualisation of high intensity focused ultrasound exposure in the rat thigh muscle.

MRI and ultrasound fusion imaging for prenatal diagnosis

OBJECTIVE

A combination of magnetic resonance imaging (MRI) images with real time high-resolution ultrasound known as fusion imaging may improve prenatal examination. This study was undertaken to evaluate the feasibility of using fusion of MRI and ultrasound (US) in prenatal imaging.

STUDY DESIGN

This study was conducted in a tertiary referral center. All patients referred for prenatal MRI were offered to undergo fusion of MRI and US examination. All cases underwent 1.5 Tesla MRI protocol including at least 3 T2-weighted planes. The Digital Imaging and Communications in Medicine volume dataset was then loaded into the US system for manual registration of the live US image and fusion imaging examination.

RESULTS

Over the study period, 24 patients underwent fusion imaging at a median gestational age of 31 (range, 24-35) weeks. Data registration, matching and then volume navigation was feasible in all cases. Fusion imaging allowed superimposing MRI and US images therefore providing with real time imaging capabilities and high tissue contrast. It also allowed adding a real time Doppler signal on MRI images. Significant fetal movement required repeat-registration in 15 (60%) cases. The average duration of the overall additional scan with fusion imaging was 10 ± 5 minutes.

CONCLUSION

The combination of fetal real time MRI and US image fusion and navigation is feasible. Multimodality fusion imaging may enable easier and more extensive prenatal diagnosis.