The role of interventional radiology and molecular imaging for near infrared photoimmunotherapy

Near infrared photoimmunotherapy (NIR-PIT) is a recently approved cancer therapy for recurrent head and neck cancer. It involves the intravenous administration of an antibody-photoabsorber (IRDye700DX: IR700) conjugate (APC) to target cancer cells, followed 24 h later by exposure to near infrared light to activate cell-specific cytotoxicity. NIR-PIT selectively targets cancer cells for destruction and activates a strong anticancer host immunity. The fluorescent signal emitted by IR700 enables the visualization of the APC in vivo using fluorescence imaging. Similarly, the activation of IR700 during therapy can be monitored by loss of fluorescence. NIR-PIT can be used with a variety of antibodies and therefore, a variety of cancer types. However, in most cases, NIR-PIT requires direct light exposure only achieved with interstitial diffuser light fibers that are placed with image-guided interventional needle insertion. In addition, the unique nature of NIR-PIT cell death, means that metabolic molecular imaging techniques such as PET and diffusion MRI can be used to assess therapeutic outcomes. This mini-review focuses on the potential implications of NIR-PIT for interventional radiology and therapeutic monitoring.

Impact of cardiac and respiratory motion on the 3D accuracy of image-guided interventions on monoplane systems

PURPOSE

Image-guided intervention (IGI) systems have the potential to increase the efficiency in interventional cardiology but face limitations from motion. Even though motion compensation approaches have been proposed, the resulting accuracy has rarely been quantified using in vivo data. The purpose of this study is to investigate the potential benefit of motion-compensation in IGS systems.

METHODS

Patients scheduled for left atrial appendage closure (LAAc) underwent pre- and postprocedural non-contrast-enhanced cardiac magnetic resonance imaging (CMR). According to the clinical standard, the final position of the occluder device was routinely documented using x-ray fluoroscopy (XR). The accuracy of the IGI system was assessed retrospectively based on the distance of the 3D device marker location derived from the periprocedural XR data and the respective location as identified in the postprocedural CMR data.

RESULTS

The assessment of the motion-compensation depending accuracy was possible based on the patient data. With motion synchronization, the measured accuracy of the IGI system resulted similar to the estimated accuracy, with almost negligible distances of the device marker positions identified in CMR and XR. Neglection of the cardiac and/or respiratory phase significantly increased the mean distances, with respiratory motion mainly reducing the accuracy with rather low impact on the precision, whereas cardiac motion decreased the accuracy and the precision of the image guidance.

CONCLUSIONS

In the presented work, the accuracy of the IGI system could be assessed based on in vivo data. Motion consideration clearly showed the potential to increase the accuracy in IGI systems. Where the general decrease in accuracy in non-motion-synchronized data did not come unexpected, a clear difference between cardiac and respiratory motion-induced errors was observed for LAAc data. Since sedation and intervention location close to the large vessels likely impacts the respiratory motion contribution, an intervention-specific accuracy analysis may be useful for other interventions.

Age-associated spinal stenosis in the turquoise killifish

Aging triggers spinal degeneration, including common spinal stenosis, which causes back and leg pain in older individuals, significantly impacting their quality of life. Here, we explored aging traits in turquoise killifish spines, potentially offering a model for age-linked spinal stenosis in humans. Aged turquoise killifish exhibited body shape deformation and increased vertebral collapse, which was further accelerated by spawning. High-resolution CT scans revealed suppressed cortical bone thickness and hemal arch area in vertebrae due to spawning, and osteophyte formation was observed in both aged and breeding fish populations. Scale mineralization mirrored these changes, increasing with age but being suppressed by spawning. The expression of sp7, sox9b, axin1, and wnt4a/b genes can be utilized to monitor age- and reproduction-dependent spine deformation. This study demonstrates that turquoise killifish and humans share certain phenotypes of age-related vertebral abnormalities, suggesting that turquoise killifish could serve as a potential model for studying human spinal stenosis.

Bimodal artificial intelligence using TabNet for differentiating spinal cord tumors-Integration of patient background information and images

We proposed a bimodal artificial intelligence that integrates patient information with images to diagnose spinal cord tumors. Our model combines TabNet, a state-of-the-art deep learning model for tabular data for patient information, and a convolutional neural network for images. As training data, we collected 259 spinal tumor patients (158 for schwannoma and 101 for meningioma). We compared the performance of the image-only unimodal model, table-only unimodal model, bimodal model using a gradient-boosting decision tree, and bimodal model using TabNet. Our proposed bimodal model using TabNet performed best (area under the receiver-operating characteristic curve [AUROC]: 0.91) in the training data and significantly outperformed the physicians' performance. In the external validation using 62 cases from the other two facilities, our bimodal model showed an AUROC of 0.92, proving the robustness of the model. The bimodal analysis using TabNet was effective for differentiating spinal tumors.

Robot Partial Prostatectomy for Anterior Cancer: Long-term Functional and Oncological Outcomes at 7 Years

Partial prostatectomy has been described as an alternative to focal ablation therapy for the management of localized low- to intermediate-risk prostate cancer. This report aims to describe the long-term outcomes in a series of 28 men (2000-2022) who underwent robotic-assisted anterior partial prostatectomy (APP) for anteriorly located tumors entirely or partially within the anterior fibromuscular stroma. The median follow-up is 7 yr (interquartile range [IQR]: 4.2-8). The median prostate-specific antigen (PSA) before APP was 9.6 (6-11). Continence remained uninterrupted in 92% of patients. Erectile function without drug remained uninterrupted in 69%. The median nadir PSA after APP was 0.36 ng/ml (IQR: 0.25-0.60). Cancer recurrence at biopsies at the margins of the primary cancer resected area in case of a PSA elevation was observed in eight patients and led to salvage completion robotic radical prostatectomy at a median time of 3.25 yr (IQR: 2.4-6). Freedom from post-APP cancer recurrence at 7 yr was 62.7% (35.0-81.3%). Pre-APP tumor volume at magnetic resonance imaging (MRI) and volume of grade 4/5 were predictive of recurrence. Freedom from biochemical recurrence after completion radical prostatectomy at 7 yr was 94.7% (68.1-99.3%). All 28 patients are alive. No one had systemic treatment or metastases. These results confirm our initial report of robotic APP with good functional results and acceptable oncological results. The use of the inclusion criteria of pre-APP tumor volume at MRI <3 cc may decrease the risk of recurrence.

Patient summary

In this report, we looked at outcomes for infrequent cases of anterior prostate cancer treated with anterior partial prostatectomy, an uncommon surgical procedure as an alternative to in situ focal ablation therapy, to better preserve functional outcomes as compared with whole gland therapy. We found that functional outcomes of uninterrupted continence and erectile function were good. Out of 28 patients, eight had recurrence in the remaining prostate and were treated with a second surgical procedure, radical prostatectomy, which was feasible. We conclude that this new technique is feasible with good functional results and acceptable oncological results, which can be shared with the patients.

Twin-S: a digital twin for skull base surgery

PURPOSE

Digital twins are virtual replicas of real-world objects and processes, and they have potential applications in the field of surgical procedures, such as enhancing situational awareness. We introduce Twin-S, a digital twin framework designed specifically for skull base surgeries.

METHODS

Twin-S is a novel framework that combines high-precision optical tracking and real-time simulation, making it possible to integrate it into image-guided interventions. To guarantee accurate representation, Twin-S employs calibration routines to ensure that the virtual model precisely reflects all real-world processes. Twin-S models and tracks key elements of skull base surgery, including surgical tools, patient anatomy, and surgical cameras. Importantly, Twin-S mirrors real-world drilling and updates the virtual model at frame rate of 28.

RESULTS

Our evaluation of Twin-S demonstrates its accuracy, with an average error of 1.39 mm during the drilling process. Our study also highlights the benefits of Twin-S, such as its ability to provide augmented surgical views derived from the continuously updated virtual model, thus offering additional situational awareness to the surgeon.

CONCLUSION

We present Twin-S, a digital twin environment for skull base surgery. Twin-S captures the real-world surgical progresses and updates the virtual model in real time through the use of modern tracking technologies. Future research that integrates vision-based techniques could further increase the accuracy of Twin-S.

Local tumor control of intermediate and advanced stage hepatocellular carcinoma after local ablative treatment with image-guided interstitial high-dose-rate brachytherapy: A subgroup analysis of 286 HCC nodules

PURPOSE

Image-guided interstitial high-dose-rate brachytherapy (iBT) has been demonstrated to offer high local tumor control rates (LTC) of >90% after local ablation of intermediate and advanced hepatocellular carcinoma (HCC; BCLC B and C). The purpose of this study was to show the efficacy of iBT stratified by subgroups and to identify clinical characteristics associated with superior local tumor control (LTC) based on a highly heterogenous patient population METHODS AND MATERIALS: A cumulative number of 286 HCC nodules in 107 patients were retrospectively analyzed. Clinical and imaging follow-ups were conducted every 3 months after treatment. Analyzed clinical factors were: etiology, presence of liver cirrhosis, radiographic features, lesion size, pretreatment, administered dose, presence of portal hypertension, portal vein thrombosis, and level of alpha-fetoprotein (AFP).

RESULTS

LTC rate was 88.8% for a median follow-up of 14.3 months (range 3-81 months; 95% CI: 85-92%). Median minimal enclosing tumor dose (D100) was 16.1 Gy (range 7.1-30.3 Gy; reference dose 15 Gy). Subgroup analysis showed significant fewer local recurrences for alcoholic liver disease (ALD)-related HCCs compared to those related to other causes of liver cirrhosis (nonalcoholic fatty liver disease, virus-related liver cirrhosis and other causes) (p = 0.015). LTC was significantly lower after prior surgical resection (p = 0.046). No significant variance was observed for the applied D100 in each group or for all other clinical factors tested.

CONCLUSIONS

IBT achieves high LTC rates across treated subgroups. However, further studies should particularly address the possible impact of underlying etiology on local recurrence with emphasis on a possible higher radiosensitivity of ALD-related HCCs.

An integrated navigation system based on a dedicated breast support device for MRI-guided breast biopsy

PURPOSE

Breast cancer is currently the cancer type with the highest incidence in the world, and it is extremely harmful to women's health. MRI-guided breast biopsy is a common method in clinical examination of breast cancer. However, traditional breast biopsy is less accurate and takes a long time. In this study, an integrated navigation system (INS) based on a dedicated breast support device (DBSD) was proposed to assist doctors in biopsy.

METHODS

The grid-shaped DBSD can reduce the displacement and deformation of the breast during the biopsy operation and is convenient for puncture. The robot system based on the DBSD is designed to assist doctors in performing puncture action. The software system has functions such as registration, path planning, and real-time tracking of biopsy needles based on the DBSD, which can assist doctors in completing the entire biopsy procedure. A series of experiments are designed to verify the feasibility and accuracy of the system.

RESULTS

Experiments prove that the robot system has reasonable structure and meets the requirements of MR compatibility. The latency of the INS during intraoperative navigation is 0.30 ± 0.03 s. In the phantom puncture experiment, the puncture error under the navigation of the INS is 1.04 ± 0.15 mm.

CONCLUSION

The INS proposed in this paper can be applied to assist doctors in breast biopsy in MR environment, improve the accuracy of biopsy and shorten the time of biopsy. The experimental results show that the system is feasible and accurate.

A neuroendoscopic navigation system based on dual-mode augmented reality for minimally invasive surgical treatment of hypertensive intracerebral hemorrhage

BACKGROUND AND OBJECTIVE

Hypertensive intracerebral hemorrhage is characterized by a high rate of morbidity, mortality, disability and recurrence. Neuroendoscopy has been utilized for treatment as an advanced technology. However, traditional neuroendoscopy allows professionals to see only tissue surfaces, and the field of vision is limited, which cannot provide spatial guidance. In this study, an AR-based neuroendoscopic navigation system is proposed to assist surgeons in locating and clearing hematoma.

METHODS

The neuroendoscope can be registered through the vector closed loop algorithm. The single-shot method is designed to register medical images with patients precisely. Real-time AR is realized based on video stream fusion. Dual-mode AR navigation is proposed to provide comprehensive guidance from catheter implantation to hematoma removal. A series of experiments is designed to validate the accuracy and significance of this system.

RESULTS

The average root mean square error of the registration between medical images and patients is 0.784 mm, and the variance is 0.1426 mm. The pixel mismatching degrees are less than 1% in different AR modes. In catheter implantation experiments, the average error of distance is 1.28 mm, and the variance is 0.43 mm, while the average error of angles is 1.34°, and the variance is 0.45°. Comparative experiments are also conducted to evaluate the feasibility of this system.

CONCLUSION

This system can provide stereo images with depth information fused with patients to guide surgeons to locate targets and remove hematoma. It has been validated to have high accuracy and feasibility.

Safety and efficacy of image-guided retrocalcaneal bursa corticosteroid injection for the treatment of retrocalcaneal bursitis

OBJECTIVE

To determine the safety and efficacy of image-guided retrocalcaneal bursa corticosteroid injection for retrocalcaneal bursitis.

MATERIALS AND METHODS

After IRB approval, all fluoroscopically guided and ultrasound-guided retrocalcaneal bursa injections (2013-2019) were retrospectively evaluated. Pre-procedure US and radiographs were scored by 2 blinded radiologists in consensus for Achilles tendinosis and retrocalcaneal bursitis (0-3 scale), Achilles enthesopathy (present/absent), and Haglund deformity (present/absent). Pre- and post-procedure pain scores (0-10 scale) evaluated short-term response at 1-4 weeks: excellent (7-10 point decline), good (4-6 point decline), fair (1-3 point decline), or no response. Paired t-test determined significance of short-term improvement. Kaplan-Meier method analyzed time to progression to surgery or complication at 6-month minimum follow-up. Logistic regression analysis evaluated for association between demographic and imaging variables and negative outcome.

RESULTS

Two hundred eighteen injections (181 female; mean 54.5 years) performed under ultrasonographic (157, 72%) or fluoroscopic (61, 28%) guidance were evaluated for complication and long-term outcomes. Injections with short-term follow-up (n = 62) yielded excellent or good response in 62.9% (p < 0.00001). Thirty patients (14%) had subsequent elective Achilles surgery. Bursal Doppler flow was associated with progression to surgery (p = 0.00042). No differences were identified in outcomes between US and fluoroscopic-guidance cohorts. Four Achilles ruptures (1.8%) were identified 15-59 days post-injection, each with immediately preceding acute injury.

CONCLUSION

Image-guided retrocalcaneal bursa corticosteroid injection yields significant short-term decrease in pain score in majority (63%) of patients. Subsequent Achilles tendon rupture rate was 1.8%. Bursa Doppler flow was significantly correlated with progression to surgery and may represent a negative prognostic indicator.

Cranial neurosurgical robotics

OBJECT

The purpose of this review is to highlight the major factors limiting the progress of robotics development in the field of cranial neurosurgery.

METHODS

A literature search was performed focused on published reports of any Neurosurgical technology developed for use in cranial neurosurgery. Technology was reviewed and assessed for strengths and weaknesses, use in patients and whether or not the project was active or closed.

RESULTS

Published reports of 24 robots are discussed going back to 1985. In total, there were 9 robots used in patients (PUMA, Robot Hand, EXPERT, Neuromate, Evolution 1, ROSA, iSYS1, NeuroArm and NeuRobot) and only 2 active today (ROSA, NeuroArm). Of all clinically active systems, only three were used in more than 30 patients (ROSA, iSYS1 & NeuroArm). Projects were limited by cost, technology adoption, and clinical utility to actually improve workflow. The most common use of developed robots is for Stereotaxis.

CONCLUSIONS

There is a clear void in the area of cranial neurosurgery regarding robotics technology despite success in other fields of surgery. Significant factors such as cost, technology limitations, market size and regulatory pathway all contribute to a steep gradient for success.

Anatomy-guided multimodal registration by learning segmentation without ground truth: Application to intraprocedural CBCT/MR liver segmentation and registration

Multimodal image registration has many applications in diagnostic medical imaging and image-guided interventions, such as Transcatheter Arterial Chemoembolization (TACE) of liver cancer guided by intraprocedural CBCT and pre-operative MR. The ability to register peri-procedurally acquired diagnostic images into the intraprocedural environment can potentially improve the intra-procedural tumor targeting, which will significantly improve therapeutic outcomes. However, the intra-procedural CBCT often suffers from suboptimal image quality due to lack of signal calibration for Hounsfield unit, limited FOV, and motion/metal artifacts. These non-ideal conditions make standard intensity-based multimodal registration methods infeasible to generate correct transformation across modalities. While registration based on anatomic structures, such as segmentation or landmarks, provides an efficient alternative, such anatomic structure information is not always available. One can train a deep learning-based anatomy extractor, but it requires large-scale manual annotations on specific modalities, which are often extremely time-consuming to obtain and require expert radiological readers. To tackle these issues, we leverage annotated datasets already existing in a source modality and propose an anatomy-preserving domain adaptation to segmentation network (APA2Seg-Net) for learning segmentation without target modality ground truth. The segmenters are then integrated into our anatomy-guided multimodal registration based on the robust point matching machine. Our experimental results on in-house TACE patient data demonstrated that our APA2Seg-Net can generate robust CBCT and MR liver segmentation, and the anatomy-guided registration framework with these segmenters can provide high-quality multimodal registrations.

Native contrast visualization and tissue characterization of myocardial radiofrequency ablation and acetic acid chemoablation lesions at 0.55 T

PURPOSE

Low-field (0.55 T) high-performance cardiovascular magnetic resonance (CMR) is an attractive platform for CMR-guided intervention as device heating is reduced around 7.5-fold compared to 1.5 T. This work determines the feasibility of visualizing cardiac radiofrequency (RF) ablation lesions at low field CMR and explores a novel alternative method for targeted tissue destruction: acetic acid chemoablation.

METHODS

N = 10 swine underwent X-ray fluoroscopy-guided RF ablation (6-7 lesions) and acetic acid chemoablation (2-3 lesions) of the left ventricle. Animals were imaged at 0.55 T with native contrast 3D-navigator gated T1-weighted T1w) CMR for lesion visualization, gated single-shot imaging to determine potential for real-time visualization of lesion formation, and T1 mapping to measure change in T1 in response to ablation. Seven animals were euthanized on ablation day and hearts imaged ex vivo. The remaining animals were imaged again in vivo at 21 days post ablation to observe lesion evolution.

RESULTS

Chemoablation lesions could be visualized and displayed much higher contrast than necrotic RF ablation lesions with T1w imaging. On the day of ablation, in vivo myocardial T1 dropped by 19 ± 7% in RF ablation lesion cores, and by 40 ± 7% in chemoablation lesion cores (p < 4e-5). In high resolution ex vivo imaging, with reduced partial volume effects, lesion core T1 dropped by 18 ± 3% and 42 ± 6% for RF and chemoablation, respectively. Mean, median, and peak lesion signal-to-noise ratio (SNR) were all at least 75% higher with chemoablation. Lesion core to myocardium contrast-to-noise (CNR) was 3.8 × higher for chemoablation. Correlation between in vivo and ex vivo CMR and histology indicated that the periphery of RF ablation lesions do not exhibit changes in T1 while the entire extent of chemoablation exhibits T1 changes. Correlation of T1w enhancing lesion volumes indicated in vivo estimates of lesion volume are accurate for chemoablation but underestimate extent of necrosis for RF ablation.

CONCLUSION

The visualization of coagulation necrosis from cardiac ablation is feasible using low-field high-performance CMR. Chemoablation produced a more pronounced change in lesion T1 than RF ablation, increasing SNR and CNR and thereby making it easier to visualize in both 3D navigator-gated and real-time CMR and more suitable for low-field imaging.

Evaluation of camera-based freehand SPECT in preoperative sentinel lymph node mapping for melanoma patients

BACKGROUND

Assessment of lymphatic status via sentinel lymph node (SLN) biopsy is an integral and crucial part of melanoma surgical oncology. The most common technique for sentinel node mapping is preoperative planar scintigraphy of an injected gamma-emitting lymphatic tracer followed by intraoperative node localization using a non-imaging gamma probe with auditory feedback. In recent years, intraoperative visualization of SLNs in 3D has become possible by coupling the probe to an external system capable of tracking its location and orientation as it is read out, thereby enabling computation of the 3D distribution of the tracer (freehand SPECT). In this project, the non-imaging probe of the fhSPECT system was replaced by a unique handheld gamma camera containing an array of sodium iodide crystals optically coupled to an array of silicon photomultipliers (SiPMs). A feasibility study was performed in which preoperative SLN mapping was performed using camera fhSPECT and the number of detected nodes was compared to that visualized by lymphoscintigraphy, probe fhSPECT, and to the number ultimately excised under non-imaging probe guidance.

RESULTS

Among five subjects, SLNs were detected in nine lymphatic basins, with one to five SLNs detected per basin. A basin-by-basin comparison showed that the number of SLNs detected using camera fhSPECT exceeded that using lymphoscintigraphy and probe fhSPECT in seven of nine basins and five of five basins, respectively. (Probe fhSPECT scans were not performed for four basins.) It exceeded the number excised under non-imaging probe guidance for seven of nine basins and equaled the number excised for the other two basins.

CONCLUSIONS

Freehand SPECT using a prototype SiPM-based gamma camera demonstrates high sensitivity for detection of SLNs in a preoperative setting. Camera fhSPECT is a potential means for efficiently obtaining real-time 3D activity distribution maps in applications such as image-guided percutaneous biopsy, and surgical SLN biopsy or radioguided tumor excision.

Therapeutic Concepts for Oligometastatic Gastrointestinal Tumours

Background

Clinical trials have proven a survival benefit from applying local therapies for oligometastatic cancers of various origin.

Summary

Today, the definition of oligometa-static disease is based on limited lesion numbers and organ systems involved. Treatment guidelines by the European Organisation for Research and Treatment of Cancer (EORTC), European Society for Medical Oncology (ESMO) and several other groups suggest a threshold of up to 5 tumours. Established biological markers indicating the aggressiveness of a given tumour (and therefore suggesting local treatment only or the addition of or complete switch to systemic therapies) are missing, except for disease-free survival, the only recommended parameter for patient selection beyond lesion count.

Key Message

The following article discusses clinical implications as well as local techniques established for the treatment of oligometastatic disease.

A "eye-in-body" integrated surgery robot system for stereotactic surgery

PURPOSE

Current stereotactic surgical robots system relies on cumbersome operations such as calibration, tracking and registration to establish the accurate intraoperative coordinate transformation chain, which makes the system not easy to use. To overcome this problem, a novel stereotactic surgical robot system has been proposed and validated.

METHODS

First, a hand-eye integrated scheme is proposed to avoid the intraoperative calibration between robot arm and motion tracking system. Second, a special reference-tool-based patient registration and tracking method is developed to avoid intraoperative registration. Third, a model-free visual servo method is used to reduce the accuracy requirement of hand-eye relationship and robot kinematic model. Finally, a prototype of the system is constructed and performance tests and a pedicle screw drilling experiment are performed.

RESULTS

The results show that the proposed system has acceptable accuracy. The target positioning error in the plane was - 0.68 ± 0.52 mm and 0.06 ± 0.41 mm. The orientation error was 0.43 ± 0.25°. The pedicle screw drilling experiment shows that the system can complete accurate stereotactic surgery.

CONCLUSIONS

The stereotactic surgical robot system described in this paper can perform stereotactic surgery without the intraoperative hand-eye calibration and nor manual registration and can achieve an acceptable position and orientation accuracy while tolerating the errors in the hand-eye coordinate transformation error and the robot kinematics model error.

An open electromagnetic tracking framework applied to targeted liver tumour ablation

PURPOSE

Electromagnetic tracking is a core platform technology in the navigation and visualisation of image-guided procedures. The technology provides high tracking accuracy in non-line-of-sight environments, allowing instrument navigation in locations where optical tracking is not feasible. EMT can be beneficial in applications such as percutaneous radiofrequency ablation for the treatment of hepatic lesions where the needle tip may be obscured due to difficult liver environments (e.g subcutaneous fat or ablation artefacts). Advances in the field of EMT include novel methods of improving tracking system accuracy, precision and error compensation capabilities, though such system-level improvements cannot be readily incorporated in current therapy applications due to the 'blackbox' nature of commercial tracking solving algorithms.

METHODS

This paper defines a software framework to allow novel EMT designs, and improvements become part of the global design process for image-guided interventions. An exemplary framework is implemented in the Python programming language and demonstrated with the open-source Anser EMT system. The framework is applied in the preclinical setting though targeted liver ablation therapy on an animal model.

RESULTS

The developed framework was tested with the Anser EMT electromagnetic tracking platform. Liver tumour targeting was performed using the tracking framework with the CustusX navigation platform using commercially available electromagnetically tracked needles. Ablation of two tumours was performed with a commercially available ablation system. Necropsy of the tumours indicated ablations within 5 mm of the tumours.

CONCLUSIONS

An open-source framework for electromagnetic tracking was presented and effectively demonstrated in the preclinical setting. We believe that this framework provides a structure for future advancement in EMT system in and customised instrument design.

Efficacy and safety of CT-guided high-dose-rate interstitial brachytherapy in primary and secondary malignancies of the pancreas

PURPOSE

To evaluate efficacy and safety of CT-guided iBT in patients with primary and secondary malignancies of the pancreas.

MATERIAL AND METHODS

13 patients with 13 lesions of the pancreatic corpus and tail were included: 8 secondary malignancies (metastatic lesions = ML) and 5 primary malignancies, including 3 primary tumors (PT) and 2 isolated locoregional recurrences (ILR) after surgical resection were treated with image-guided iBT using a 192iridium source (single fraction irradiation). Every 3 months after treatment clinical and imaging follow-up were conducted to evaluate efficacy. Peri- and postinterventional complications were assessed descriptively.

RESULTS

The median diameter of the gross tumor volume (GTV) was 3 cm (range 1-6.5 cm), treated with a median D100 (minimal enclosing tumor dose) of 15.3 Gy (range 9.2-25.4 Gy). Local tumor control (LTC) was 92.3% within a median follow-up period of 6.7 months (range 3.2-55.7 months). Cumulative median progression free survival (PFS) was 6.2 months (range 2.8-25.7 months; PFS of primary and secondary malignancies was 5.8 and 6.2 months, respectively). Cumulative median over all survival (OS) after iBT was 16.2 months (range 3.3-55.7 months; OS of primary and secondary malignancies was 7.4 months and 45.6 months, respectively). 1 patient developed mild acute pancreatits post iBT, spontanously resolved within 1 week. No severe adverse events (grade 3+) were recorded.

CONCLUSION

Image-guided iBT is a safe and particularly effective treatment in patients with primary and secondary malignancies of the pancreas and might provide a well-tolerated additional therapeutic option in the multidisciplinary management of selected patients.

Weakly-supervised convolutional neural networks for multimodal image registration

One of the fundamental challenges in supervised learning for multimodal image registration is the lack of ground-truth for voxel-level spatial correspondence. This work describes a method to infer voxel-level transformation from higher-level correspondence information contained in anatomical labels. We argue that such labels are more reliable and practical to obtain for reference sets of image pairs than voxel-level correspondence. Typical anatomical labels of interest may include solid organs, vessels, ducts, structure boundaries and other subject-specific ad hoc landmarks. The proposed end-to-end convolutional neural network approach aims to predict displacement fields to align multiple labelled corresponding structures for individual image pairs during the training, while only unlabelled image pairs are used as the network input for inference. We highlight the versatility of the proposed strategy, for training, utilising diverse types of anatomical labels, which need not to be identifiable over all training image pairs. At inference, the resulting 3D deformable image registration algorithm runs in real-time and is fully-automated without requiring any anatomical labels or initialisation. Several network architecture variants are compared for registering T2-weighted magnetic resonance images and 3D transrectal ultrasound images from prostate cancer patients. A median target registration error of 3.6 mm on landmark centroids and a median Dice of 0.87 on prostate glands are achieved from cross-validation experiments, in which 108 pairs of multimodal images from 76 patients were tested with high-quality anatomical labels.

Tissue mimicking materials in image-guided needle-based interventions: A review

Image-guided interventions are widely employed in clinical medicine, which brings significant revolution in healthcare in recent years. However, it is impossible for medical trainees to experience the image-guided interventions physically in patients due to the lack of certificated skills. Therefore, training phantoms, which are normally tissue mimicking materials, are widely used in medical research, training, and quality assurance. This review focuses on the tissue mimicking materials used in image-guided needle-based interventions. In this case, we need to investigate the microstructure characteristics and mechanical properties (for needle intervention), optical properties and acoustical properties (for imaging) of these training phantoms to compare with the related properties of human real tissues. The widely used base materials, additives and the corresponding concentrations of the training phantoms are summarized from the literatures in recent ten years. The microstructure characteristics, mechanical behavior, optical properties and acoustical properties of the tissue mimicking materials are investigated, accompanied with the common experimental methods, apparatus and theoretical algorithm. The influence of the concentrations of the base materials and additives on these characteristics are compared and classified. In this review, we assess a comprehensive overview of the existing techniques with the main accomplishments, and limitations as well as recommendations for tissue mimicking materials used in image-guided needle-based interventions.

Tomosynthesis implementation with adaptive online calibration on clinical C-arm systems

PURPOSE

Cone beam computed tomography (CBCT) systems offer physicians crucial 3D and 2D imaging capabilities during interventions. However, certain medical applications only require very specific information from the CBCTs (e.g., determination of the position of high-contrast objects). In diagnostics, tomosynthesis techniques can be used in these cases to minimize dose exposure. Therefore, integrating such techniques on CBCT systems could also be beneficial for interventions. In this paper, we investigate the performance of our implementation of circular tomosynthesis on a CBCT device.

METHODS

The tomosynthesis scan trajectory is realized with step-and-shoot on a clinical C-arm device. The online calibration algorithm uses conventionally acquired 3D CBCT of the scanned object as prior knowledge to correct the imaging geometries. The online calibration algorithm was compared to an offline calibration to test its performance. A ball bearing phantom was used to evaluate the reconstructions with respect to geometric distortions. The evaluation was done for three different scenarios to test the robustness of our tomosynthesis implementation against object deviations (e.g., pen) and different object positioning.

RESULTS

The circular tomosynthesis was tested on a ball bearing and an anthropomorphic phantom. The results show that the calibration is robust against isocenter shifts and object deviations in the CBCT. All reconstructions used 100 projections and displayed limited angle artifacts. The accuracy of the positions and shapes of high-contrast objects were, however, determined precisely. (The maximal center position deviation is 0.31 mm.) CONCLUSION: For medical procedures that primarily determine the precise position of high-contrast objects, circular tomosynthesis could offer an approach to reduce dose exposure.

Cardiovascular magnetic resonance guided ablation and intra-procedural visualization of evolving radiofrequency lesions in the left ventricle

BACKGROUND

Radiofrequency (RF) ablation has become a mainstay of treatment for ventricular tachycardia, yet adequate lesion formation remains challenging. This study aims to comprehensively describe the composition and evolution of acute left ventricular (LV) lesions using native-contrast cardiovascular magnetic resonance (CMR) during CMR-guided ablation procedures.

METHODS

RF ablation was performed using an actively-tracked CMR-enabled catheter guided into the LV of 12 healthy swine to create 14 RF ablation lesions. T2 maps were acquired immediately post-ablation to visualize myocardial edema at the ablation sites and T1-weighted inversion recovery prepared balanced steady-state free precession (IR-SSFP) imaging was used to visualize the lesions. These sequences were repeated concurrently to assess the physiological response following ablation for up to approximately 3 h. Multi-contrast late enhancement (MCLE) imaging was performed to confirm the final pattern of ablation, which was then validated using gross pathology and histology.

RESULTS

Edema at the ablation site was detected in T2 maps acquired as early as 3 min post-ablation. Acute T2-derived edematous regions consistently encompassed the T1-derived lesions, and expanded significantly throughout the 3-h period post-ablation to 1.7 ± 0.2 times their baseline volumes (mean ± SE, estimated using a linear mixed model determined from n = 13 lesions). T1-derived lesions remained approximately stable in volume throughout the same time frame, decreasing to 0.9 ± 0.1 times the baseline volume (mean ± SE, estimated using a linear mixed model, n = 9 lesions).

CONCLUSIONS

Combining native T1- and T2-based imaging showed that distinctive regions of ablation injury are reflected by these contrast mechanisms, and these regions evolve separately throughout the time period of an intervention. An integrated description of the T1-derived lesion and T2-derived edema provides a detailed picture of acute lesion composition that would be most clinically useful during an ablation case.

Partial Prostatectomy for Anterior Cancer: Short-term Oncologic and Functional Outcomes

BACKGROUND

Focal ablative therapy may be a suboptimal option for anterior prostate cancers (APCs) reaching the prostate apex due to concerns for thermal injury to the external sphincter.

OBJECTIVE

To explore the technical feasibility of anterior partial prostatectomy (APP) for isolated APCs detected by magnetic resonance imaging (MRI), and to report short-term oncologic and functional outcomes.

DESIGN, SETTING, AND PARTICIPANTS

Following institutional review board approval, over an 8-yr period (2008-2015) 17 consenting patients were enrolled in a prospective single-arm single-center Innovation, Development, Exploration, Assessment, Long-term (IDEAL) phase 2a study. Inclusion criteria comprised preurethral, low- to intermediate-risk APC diagnosed by MRI, and targeted biopsies. Robotic template APP was performed; posterolateral aspect of the submontanal urethra, peripheral zone, and periprostatic tissues were preserved intact. Median follow-up was 30 mo (interquartile range [IQR]: 25-70).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We noted the incidence of perioperative complications and examined reports of pathology, prostate-specific antigen (PSA), imaging, biopsies, and questionnaires.

RESULTS AND LIMITATIONS

Preoperatively, median PSA was 9.8 ng/ml, Gleason score was 6-7 (3 + 4), and cancer volume was 3.7cm³ (IQR: 1.7-4.6). The technique was feasible in all cases. Perioperative complications included anastomotic leak (12%; G2), urinary tract infection (6%; G2), and transient intestinal ileus in one case (6%; G2). At 3 mo, continence and potency rates were 100% and 83%, respectively. Median nadir PSA was 0.4 ng/ml (IQR: 0.3-0.7). All margins and posterolateral margins rates were 55% and 35%, respectively. APC recurrence-free survival at 2 yr was 0.86 (95% confidence interval [CI], 0.55-0.96). Four patients (24%) who recurred underwent an uncomplicated completion of robot-assisted prostatectomy. Regarding limitations, CIs are quite wide for reported outcomes.

CONCLUSIONS

Robotic partial prostatectomy for isolated APC is feasible with good functional results. While promising, much more research is needed to verify our initial outcomes and appropriately position APP in the treatment paradigms for APC.

PATIENT SUMMARY

We explored a novel approach for partial prostatic surgical ablation for prostate cancer located in the anterior part of the prostate as an alternative to other focal ablative techniques.

Real-time 6DoF pose recovery from X-ray images using library-based DRR and hybrid optimization

PURPOSE

Real-time 6 degrees of freedom (6DoF) pose recovery and tracking from X-ray images is a key enabling technology for many interventional imaging applications. However, real-time 2D/3D registration is a very challenging problem because of the heavy computation in iterative digitally reconstructed radiograph (DRR) generation. In this paper, we propose a real-time 2D/3D registration framework using library-based DRRs to achieve high computational efficiency.

METHOD

The proposed method pre-computes a library of canonical DRRs and reconstructs library-based DRRs (libDRRs) during registration without online rendering. The transformation parameters are decoupled to 2 geometry-relevant and 4 geometry-irrelevant ones so that canonical DRRs only need to cover the variation of 2 geometry-relevant parameters, making it practical to be pre-computed and stored. The 2D/3D registration using libDRRs is then solved as a hybrid optimization problem, i.e., continuous in geometry-irrelevant parameters while discrete in geometry-relevant parameters.

RESULTS

On 5 fluoroscopic sequences with 246 frames acquired during animal studies with a transesophageal echocardiography (TEE) probe in the field of view, 6DoF tracking of the TEE probe using the proposed method achieved a mean target registration error in the projection direction (mTREproj) of 0.81 mm, a success rate of 100 % (defined as mTREproj [Formula: see text]2.5 mm), and a registration frame rate of 23.1 fps on a pure CPU-based implementation executed in a single thread.

CONCLUSION

Using libDRRs with a hybrid optimization can significantly improve the computational efficiency (up to tenfold) for 6DoF pose recovery and tracking with little degradation in robustness and accuracy, compared to conventional intensity-based 2D/3D registration using ray casting DRRs with a continuous optimization.

Three-dimensional quantitative assessment of ablation margins based on registration of pre- and post-procedural MRI and distance map

PURPOSE

Contrast-enhanced MR images are widely used to confirm the adequacy of ablation margin after liver ablation for early prediction of local recurrence. However, quantitative assessment of the ablation margin by comparing pre- and post-procedural images remains challenging. We developed and tested a novel method for three-dimensional quantitative assessment of ablation margin based on non-rigid image registration and 3D distance map.

METHODS

Our method was tested with pre- and post-procedural MR images acquired in 21 patients who underwent image-guided percutaneous liver ablation. The two images were co-registered using non-rigid intensity-based registration. After the tumor and ablation volumes were segmented, target volume coverage, percent of tumor coverage, and Dice similarity coefficient were calculated as metrics representing overall adequacy of ablation. In addition, 3D distance map around the tumor was computed and superimposed on the ablation volume to identify the area with insufficient margins. For patients with local recurrences, the follow-up images were registered to the post-procedural image. Three-dimensional minimum distance between the recurrence and the areas with insufficient margins was quantified.

RESULTS

The percent tumor coverage for all nonrecurrent cases was 100 %. Five cases had tumor recurrences, and the 3D distance map revealed insufficient tumor coverage or a 0-mm margin. It also showed that two recurrences were remote to the insufficient margin.

CONCLUSIONS

Non-rigid registration and 3D distance map allow us to quantitatively evaluate the adequacy of the ablation margin after percutaneous liver ablation. The method may be useful to predict local recurrences immediately following ablation procedure.

Motion-adapted catheter navigation with real-time instantiation and improved visualisation

The improvements to catheter manipulation by the use of robot-assisted catheter navigation for endovascular procedures include increased precision, stability of motion and operator comfort. However, navigation through the vasculature under fluoroscopic guidance is still challenging, mostly due to physiological motion and when tortuous vessels are involved. In this paper, we propose a motion-adaptive catheter navigation scheme based on shape modelling to compensate for these dynamic effects, permitting predictive and dynamic navigations. This allows for timed manipulations synchronised with the vascular motion. The technical contribution of the paper includes the following two aspects. Firstly, a dynamic shape modelling and real-time instantiation scheme based on sparse data obtained intra-operatively is proposed for improved visualisation of the 3D vasculature during endovascular intervention. Secondly, a reconstructed frontal view from the catheter tip using the derived dynamic model is used as an interventional aid to user guidance. To demonstrate the practical value of the proposed framework, a simulated aortic branch cannulation procedure is used with detailed user validation to demonstrate the improvement in navigation quality and efficiency.

Magnetic Resonance Imaging-Guided Transurethral Ultrasound Ablation of Prostate Tissue in Patients with Localized Prostate Cancer: A Prospective Phase 1 Clinical Trial

BACKGROUND

Magnetic resonance imaging-guided transurethral ultrasound ablation (MRI-TULSA) is a novel minimally invasive technology for ablating prostate tissue, potentially offering good disease control of localized cancer and low morbidity.

OBJECTIVE

To determine the clinical safety and feasibility of MRI-TULSA for whole-gland prostate ablation in a primary treatment setting of localized prostate cancer (PCa).

DESIGN, SETTING, AND PARTICIPANTS

A single-arm prospective phase 1 study was performed at three tertiary referral centers in Canada, Germany, and the United States. Thirty patients (median age: 69 yr; interquartile range [IQR]: 67-71 yr) with biopsy-proven low-risk (80%) and intermediate-risk (20%) PCa were treated and followed for 12 mo.

INTERVENTION

MRI-TULSA treatment was delivered with the therapeutic intent of conservative whole-gland ablation including 3-mm safety margins and 10% residual viable prostate expected around the capsule.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Primary end points were safety (adverse events) and feasibility (technical accuracy and precision of conformal thermal ablation). Exploratory outcomes included quality of life, prostate-specific antigen (PSA), and biopsy at 12 mo.

RESULTS AND LIMITATIONS

Median treatment time was 36min (IQR: 26-44) and prostate volume was 44ml (IQR: 38-48). Spatial control of thermal ablation was ±1.3mm on MRI thermometry. Common Terminology Criteria for Adverse Events included hematuria (43% grade [G] 1; 6.7% G2), urinary tract infections (33% G2), acute urinary retention (10% G1; 17% G2), and epididymitis (3.3% G3). There were no rectal injuries. Median pretreatment International Prostate Symptom Score 8 (IQR: 5-13) returned to 6 (IQR: 4-10) at 3 mo (mean change: -2; 95% confidence interval [CI], -4 to 1). Median pretreatment International Index of Erectile Function 13 (IQR: 6-28) recovered to 13 (IQR: 5-25) at 12 mo (mean change: -1; 95% CI, -5 to 3). Median PSA decreased 87% at 1 mo and was stable at 0.8 ng/ml (IQR: 0.6-1.1) to 12 mo. Positive biopsies showed 61% reduction in total cancer length, clinically significant disease in 9 of 29 patients (31%; 95% CI, 15-51), and any disease in 16 of 29 patients (55%; 95% CI, 36-74).

CONCLUSIONS

MRI-TULSA was feasible, safe, and technically precise for whole-gland prostate ablation in patients with localized PCa. Phase 1 data are sufficiently compelling to study MRI-TULSA further in a larger prospective trial with reduced safety margins.

PATIENT SUMMARY

We used magnetic resonance imaging-guided transurethral ultrasound to heat and ablate the prostate in men with prostate cancer. We showed that the treatment can be targeted within a narrow range (1mm) and has a well-tolerated side effect profile. A larger study is under way.

TRIAL REGISTRATION

NCT01686958, DRKS00005311.

Localization of Transcranial Targets for Photoacoustic-Guided Endonasal Surgeries

Neurosurgeries to remove pituitary tumors using the endonasal, transsphenoidal approach often incur the risk of patient death caused by injury to the carotid arteries hidden by surrounding sphenoid bone. To avoid this risk, we propose intraoperative photoacoustic vessel visualization with an optical fiber attached to the surgical tool and an external ultrasound transducer placed on the temple. Vessel detection accuracy is limited by acoustic propagation properties, which were investigated with k-Wave simulations. In a two-layer model of temporal bone (3200 m/s sound speed, 1-4 mm thickness) and surrounding tissues, the localization error was ≤2 mm in the tranducer's axial dimension, while temporal bone curvature further degraded target localization. Phantom experiments revealed that multiple image targets (e.g. sphenoid bone and vessels) can be visualized, particularly with coherence-based beamforming, to determine tool-to-vessel proximity despite expected localization errors. In addition, the potential flexibility of the fiber position relative to the transducer and vessel was elucidated.

Single-Session CT-Guided Percutaneous Microwave Ablation of Bilateral Adrenal Gland Hyperplasia Due to Ectopic ACTH Syndrome

Bilateral adrenalectomy is currently the only available treatment for adrenocorticotropic hormone (ACTH)-dependent Cushing's syndrome (ectopic ACTH syndrome) that is refractory to pharmacologic therapy. We describe two patients with refractory ectopic ACTH syndrome who were treated with CT-guided percutaneous microwave ablation of both hyperplastic adrenal glands in a single session: O ne was not a surgical candidate, and the other had undergone unsuccessful surgery. Following the procedure, both patients achieved substantial decreases in serum cortisol, symptomatic improvement, and decreased anti-hypertensive medication requirements.

Meningioma of the skull base: long-term outcome after image-guided stereotactic radiotherapy

PURPOSE

The purpose of this study was to analyse the feasibility, safety, and long-term efficacy of linear accelerator-based fractionated stereotactic radiotherapy for meningiomas of the skull base. We evaluated the long-term clinical outcome of patients and identified prognostic factors after fractionated stereotactic radiotherapy.

PATIENTS AND METHODS

Between 10/1995 and 03/2009, 136 patients with a median age of 57 years with skull base meningioma received fractionated stereotactic radiotherapy. A total of 34 patients had a grade I meningioma, in 102 cases no histology was obtained (grade 0). Fractionated stereotactic radiotherapy was delivered as primary treatment for 57 patients and postoperatively for 79. The patients received a mean total dose of 56.95 (min/max 32.4/63)Gy.

RESULTS

Median follow-up was 44.9 months. Overall progression-free survival was 96.9% after 3 years, 93.8% after 5 years, and 91.5% after 10 years. Patients with unknown histology showed progression-free survival rates of 100%, 98.7%, and 93.5% at 3, 5, and 10 years and patients with biopsy-proven grade I meningioma showed rates of 100% after 3 years, 91.7% after 5 years and 85.9% after 10 years. Patients with adjuvant radiotherapy showed significantly worse progression-free survival rates than patients who had been treated with primary radiotherapy (P=0.043), progression-free survival rates were independent of tumour size. The most common acute grade I symptoms were headache, fatigue, and local alopecia. The most common chronic grade I symptoms were fatigue and headache.

CONCLUSIONS

This large study showed that fractionated stereotactic radiotherapy is an effective and safe treatment modality with high progression-free survival rates for intracranial meningioma. We identified "prior surgery" as significant poor prognostic factor.

A simple and accurate method for computer-aided transapical aortic valve replacement

BACKGROUND AND PURPOSE

Transapical aortic valve replacement (TAVR) is a recent minimally invasive surgical treatment technique for elderly and high-risk patients with severe aortic stenosis. In this paper, a simple and accurate image-based method is introduced to aid the intra-operative guidance of TAVR procedure under 2-D X-ray fluoroscopy.

METHODS

The proposed method fuses a 3-D aortic mesh model and anatomical valve landmarks with live 2-D fluoroscopic images. The 3-D aortic mesh model and landmarks are reconstructed from interventional X-ray C-arm CT system, and a target area for valve implantation is automatically estimated using these aortic mesh models. Based on template-based tracking approach, the overlay of visualized 3-D aortic mesh model, landmarks and target area of implantation is updated onto fluoroscopic images by approximating the aortic root motion from a pigtail catheter motion without contrast agent. Also, a rigid intensity-based registration algorithm is used to track continuously the aortic root motion in the presence of contrast agent. Furthermore, a sensorless tracking of the aortic valve prosthesis is provided to guide the physician to perform the appropriate placement of prosthesis into the estimated target area of implantation.

RESULTS

Retrospective experiments were carried out on fifteen patient datasets from the clinical routine of the TAVR. The maximum displacement errors were less than 2.0mm for both the dynamic overlay of aortic mesh models and image-based tracking of the prosthesis, and within the clinically accepted ranges. Moreover, high success rates of the proposed method were obtained above 91.0% for all tested patient datasets.

CONCLUSION

The results showed that the proposed method for computer-aided TAVR is potentially a helpful tool for physicians by automatically defining the accurate placement position of the prosthesis during the surgical procedure.

Effective radiation dosage of three-dimensional rotational angiography in children

AIMS

Three-dimensional rotational angiography (3DRA) is a relatively new but promising imaging technique in the paediatric catheterization laboratory. However, data on effective dose (ED) of this technique in children are lacking. The purpose of this study is to provide ED of 3DRA and to correlate this with parameters readily available in daily practice. Furthermore, the effect of dose-reducing techniques is evaluated.

METHODS AND RESULTS

Effective doses were calculated with Monte Carlo PCXMC 2.0 in 14 patients who underwent a total of 17 3DRAs at our paediatric catheterization laboratory. Median age was 5.7 years (range 1 day-16.6 years). Median ED was 1.6 milliSievert (mSv) (range 0.7-4.9). Effective dose did not correlate with age and body surface area but did correlate with dose area product (DAP) and milliGray (mGy) with r(2) of 0.75 and 0.83, respectively. Reduction of the total amount of frames from 248 to 133 per rotation resulted in further dose reduction of over 50% with preserved image quality.

CONCLUSION

The median ED of 3DRA in children is 1.6 mSv and correlates with DAP and mGy. This dose can be halved by applying frame reduction. A significant further dose reduction can be achieved by obtaining additional knowledge of the equipment used.

Recent advances in imaging-guided interventions for prostate cancers

The numbers of patients diagnosed with prostate cancers is increasing due to the widespread application of prostate-specific antigen screening and subsequent prostate biopsies. The methods of systemic administration of therapeutics are not target-specific and thus cannot efficiently destroy prostate tumour cells while simultaneously sparing the surrounding normal tissues and organs. Recent advances in imaging-guided minimally invasive therapeutic techniques offer considerable potential for the effective management of prostate cancers. An objective understanding of the feasibility, effectiveness, morbidity, and deficiencies of these interventional techniques is essential for both clinical practice and scientific progress. This review presents the recent advances in imaging-guided interventional techniques for the diagnosis and treatment of prostate cancers.

Thyroid fine needle aspiration biopsy: do we really need an on-site cytopathologist?

PURPOSE

The aim of this single center study is to evaluate the effectiveness of performing ultrasound-guided thyroid fine-needle aspiration biopsies (FNAB) performed by the radiologist alone without an on-site cytopathologist.

MATERIALS AND METHODS

In this prospective randomized study, 203 patients with single nodules measuring 10mm or more underwent ultrasound-guided FNAB: 102 patients underwent FNAB performed by the radiologist accompanied by a cytopathologist (control group); 101 patients underwent FNAB by the radiologist alone (study group). In both groups biopsy time, specimen adequacy ratio, total aspiration number, cytopathologist's cytological diagnosis time (t1), cytopathologist's total time consumption (t2) were evaluated.

RESULTS

Mean total biopsy time was 8.74 ± 2.31 min in the study group and was significantly shorter than the control group's 11.97 ± 6.75 min (p=0.004). The average number of aspirations per patient in the study group was 4.00 ± 0; compared to the control group's 3.56 ± 1.23 this was significantly higher (p=0.001). t1 of the study group was 307.48 ± 226.32s; compared to 350.14 ± 247.64 s in the control group, there was no statistically significant difference (p=0.137). t2 of the study group was 672.93 ± 270.45 s; compared to the control group (707.03 ± 258.78 s) there was no statistically significant difference (p=0.360). Diagnostic adequacy of aspirated specimens was reassessed in the pathology laboratory. In the study group, 84 out of 101 aspirations and in the control group 89 out of 102 aspirations was determined as adequate with no statistically significant difference (p=0.302).

CONCLUSIONS

We believe that in centers where a cytopathologist is not available, ultrasound-guided thyroid FNAB can be adequately performed by an experienced radiologist who was effectively trained in smear preparation.