The challenging image-guided abdominal mass biopsy: established and emerging techniques ‘if you can see it, you can biopsy it’

Ultrasound-guided biopsy of challenging abdominopelvic targets

Percutaneous ultrasound-guided biopsies have become the standard of practice for tissue diagnosis in the abdomen and pelvis for many sites including liver, kidney, abdominal wall, and peripheral nodal stations. Additional targets may appear difficult or impossible to safely biopsy by ultrasound due to interposed bowel loops/vasculature, deep positioning, association with the bowel, or concern for poor visibility; however, by optimizing technique, it is often possible to safely and efficiently use real-time ultrasound guidance for sampling targets that normally would be considered only appropriate for CT guided or surgical/endoscopic biopsy.

High presacral collection approached through the perineal route: A novel computed tomography-guided technique

For a definitive diagnosis of abdomino-pelvic lesions, percutaneous aspiration or biopsy is often necessary; however, finding a safe 'window' for access is challenging. This case report discusses a novel method to approach a deep pelvic collection and also briefly reviews the various approaches to access such lesions. A sample was obtained from a non-resolving presacral collection using a CT-guided percutaneous, trans-perineal approach with repeated sessions of hydro-dissection. Successful aspiration and analysis revealed multi-drug resistant tuberculosis, thus guiding appropriate management.

Percutaneous Transhepatic Biopsy for Extrahepatic Lesions

Purpose The purpose was to assess the diagnostic accuracy and safety of percutaneous transhepatic biopsy for extrahepatic lesions.

Materials and Methods Between January 2008 and December 2019, 26 patients (17 men and 9 women; median age, 60 years) underwent percutaneous transhepatic needle biopsy for extrahepatic lesions at our institution. Transhepatic biopsy was deemed appropriate compared with other biopsy routes or methods (i.e., endoscopic or surgical). The lesions were in the porta hepatis (n = 9), retroperitoneum (n = 6), right adrenal gland (n = 4), right kidney (n = 3), lesser omentum (n = 2), duodenum (n = 1), pleura (n = 1), and inferior vena cava (n = 1). The median maximal diameter of the lesions was 45.5 mm (range, 18–148 mm). Core-needle biopsy was performed in all patients. Eighteen-gauge and 21-G needles were used in 25 and one patient, respectively. Ultrasound was used for biopsy in 21 patients, and CT fluoroscopy was used in five patients. Postbiopsy tract embolization was performed in three patients. Technical success and diagnostic accuracy of the biopsy were evaluated. Complications were recorded using the systemic inflammation response (SIR) criteria.

Results The pathological results of biopsy were carcinoma (n = 10), lymphoma (n = 9), and other diagnoses (n = 7). Technical success was obtained in all patients. The accurate diagnosis was achieved in 24 of the 26 patients (92.3%). A major complication, a bladder tamponade, was observed in one patient (3.8%) after biopsy of a right kidney lesion. A hematoma caused by iatrogenic renal injury likely obstructed the bladder outlet. Minor complications were observed in three patients (11.5%).

Conclusions Percutaneous transhepatic biopsy for extrahepatic lesions is feasible with acceptable safety.

Hydrodissection - Practical applications in ultrasound-guided breast interventions

Hydrodissection is a procedural tactic utilized in various interventions. It is a technique which helps separate structures in order to safely perform a certain procedure. This article will provide a review of hydrodissection, how to perform this technique, and why it can be useful in breast interventions.

Contrast-Enhanced Ultrasound-Guided Interventions-The New Sheriff in Town?: A Case-Based Review of Problem Solving With Ultrasound Contrast

Ultrasound (US)-guided intervention is a well-established medical procedure and offers advantages such as real-time guidance, portability, reduced cost, shortened procedure time compared with computed tomography, and lack of ionizing radiation. Ultrasound contrast agents (UCAs) are a useful adjunct to US-guided procedures. The addition of microbubble UCAs during US-guided interventions can assist with biopsy planning and lesion selection, aid in identification of target lesions, and direct the biopsy toward viable tissue. Ultrasound contrast agents have been in use outside of the United States for many years and have been used off label at select institutions across the United States before the Food and Drug Administration approval of Lumason (Bracco Diagnostics) for liver lesion evaluation in April 2016. After Food and Drug Administration approval, the use of UCAs has expanded rapidly, and UCAs are being used for a variety of clinical applications. Ultrasound contrast agents have been shown to be safe, and there is no renal toxicity. In this article, we will discuss the indications and techniques for using contrast-enhanced ultrasound during US-guided interventions, and we will present case examples where contrast-enhanced ultrasound added value.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid

The first edition of the guidelines for the use of ultrasound contrast agents was published in 2004, dealing with liver applications. The second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some nonliver applications. The third edition of the contrast-enhanced ultrasound (CEUS) guidelines was the joint World Federation for Ultrasound in Medicine and Biology-European Federation of Societies for Ultrasound in Medicine and Biology (WFUMB-EFSUMB) venture in conjunction with other regional US societies such as Asian Federation of Societies for Ultrasound in Medicine and Biology, resulting in a simultaneous duplicate on liver CEUS in the official journals of both WFUMB and EFSUMB in 2013. However, no guidelines were described mainly for Sonazoid due to limited clinical experience only in Japan and Korea. The new proposed consensus statements and recommendations provide general advice on the use of Sonazoid and are intended to create standard protocols for the use and administration of Sonazoid in hepatic and pancreatobiliary applications in Asian patients and to improve patient management.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid

The first edition of the guidelines for the use of ultrasound contrast agents was published in 2004, dealing with liver applications. The second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some nonliver applications. The third edition of the contrast-enhanced ultrasound (CEUS) guidelines was the joint World Federation for Ultrasound in Medicine and Biology-European Federation of Societies for Ultrasound in Medicine and Biology (WFUMB-EFSUMB) venture in conjunction with other regional US societies such as Asian Federation of Societies for Ultrasound in Medicine and Biology, resulting in a simultaneous duplicate on liver CEUS in the official journals of both WFUMB and EFSUMB in 2013. However, no guidelines were described mainly for Sonazoid due to limited clinical experience only in Japan and Korea. The new proposed consensus statements and recommendations provide general advice on the use of Sonazoid and are intended to create standard protocols for the use and administration of Sonazoid in hepatic and pancreatobiliary applications in Asian patients and to improve patient management.

Biopsy of Deep Pelvic and Abdominal Targets With Ultrasound Guidance: Efficacy of Compression

OBJECTIVE. The purpose of this study was to evaluate the utility of compression of tissues with the ultrasound transducer in decreasing distance to the biopsy target and establishing a safe percutaneous biopsy route to deep abdominopelvic targets. MATERIALS AND METHODS. Ultrasound-guided biopsies of nonsolid organ abdominopelvic targets performed from 2006 to 2017 were reviewed. Skin-to-target distance was measured on preprocedure CT scans for reference standard and on procedure ultrasound images for actual real-time distance after compression. The skin-to-target CT distance groupings were 0-3 cm, 3-6 cm, 6-10, cm, and > 10 cm. Deep targets were defined as > 6 cm. Differences in skin-to-target distance between static CT and compression ultrasound were calculated. Body mass index, procedure details, diagnostic yield, and complication rate were recorded. RESULTS. The biopsies of 389 patients (167 men, 222 women; mean age, 62.4 years; mean body mass index, 28.2) were assessed. Skin-to-target distance was 0-3 cm in 108 patients, 3-6 cm in 163 patients, 6-10 cm in 99 patients, and > 10 cm in 19 patients. A total of 118 deep targets were identified. The mean skin-to-target distance in the entire cohort was 5.0 cm on CT scans and 3.6 cm on ultrasound images with a 10% mean decrease in distance with ultrasound compression. For skin-to-target distances of 6-10 cm, distance decreased 39% at ultrasound, and for skin-to-target distances > 10 cm, distance decreased 48%. Thirty-three patients (8.5%) had no safe identifiable path for CT biopsy, most commonly because of intervening bowel, displacement of which at ultrasound allowed a safe biopsy trajectory. Ultrasound-guided biopsy had a diagnostic yield of 91.5% and a favorable safety profile. The complication rate was 1.3%. CONCLUSION. Application of compression with the ultrasound transducer decreased skin-to-target distance 40% or more for deep targets in addition to displacing bowel and establishing a safe path for biopsy in approximately 8.5% of cases.

Contrast-Enhanced Ultrasound in Renal Imaging and Intervention

PURPOSE OF REVIEW

In recent years, there has been renewed interest in the use of contrast-enhanced ultrasound (CEUS) in abdominal imaging and intervention. The goal of this article is to review the practical applications of CEUS in the kidney, including renal mass characterization, treatment monitoring during and after percutaneous ablation, and biopsy guidance.

RECENT FINDINGS

Current evidence suggests that CEUS allows accurate differentiation of solid and cystic renal masses and is an acceptable alternative to either computed tomography (CT) or magnetic resonance imaging (MRI) for characterization of indeterminate renal masses. CEUS is sensitive and specific for diagnosing residual or recurrent renal cell carcinoma (RCC) following percutaneous ablation. Furthermore, given its excellent spatial and temporal resolution, CEUS is well suited to demonstrate tumoral microvascularity associated with malignant renal masses and is an effective complement to conventional grayscale ultrasound (US) for percutaneous biopsy guidance. Currently underutilized, CEUS is an important problem-solving tool in renal imaging and intervention whose role will continue to expand in coming years.

Percutaneous needle biopsy of retroperitoneal lesions: technical developments

Percutaneous Needle Biopsy (PNB) is the insertion of a needle into a suspected lesion or an organ with the aim to obtain cells or tissue for diagnosis. It’s a relatively non-invasive procedure and is performed by radiologist under guidance of imaging techniques such as ultrasound (US), computed tomography (CT), fluoroscopy, magnetic resonance imaging (MRI), and positron emission tomography CT (PET-CT). The choice of imaging technique depends on the evaluation of the target lesion and patient compliance. PNB includes two categories: fine-needle aspiration biopsy (FNAB) that is the use of a thin needle (18-25 gauge) to extract cells for cytological evaluation; and core needle biopsy (CNB) that is the use of a larger needle (9-20 gauge) to extract a piece of tissue for histological evaluation. The indications for biopsy are the characterization of nature (benign or malignant) of a lesion, diagnosis and staging of tumor, and biological or immunohistochemical/genetic analisys on tissue. Success of PNB is the procurement of sufficient material to characterize lesions and to guide the patient outcome. Major complications are rare. PNB became a useful technique in diagnosis and study of retroperitoneal lesions, because of a more suitable access to specific intra-abdominal structures, lowering the risk of injury of interposed structures (such as bowel, great vessels). (www.actabiomedica.it)

Computed tomography-guided percutaneous biopsy of abdominal lesions: indications, techniques, results, and complications

Objective

To evaluate the performance of computed tomography (CT)-guided percutaneous biopsy of abdominal lesions.

Materials and Methods

This retrospective, single-center study evaluated patients submitted to CT-guided percutaneous biopsy of abdominal lesions at a cancer center, between January 2014 and June 2015. The images and patient medical records were reviewed using a standardized data collection form.

Results

We included 225 procedures performed in 212 patients, of whom 143 (63.5%) had a prior diagnosis of cancer. Of the 225 lesions biopsied, 88 (39.1%) had a suspected primary origin and 137 (60.9%) were suspected metastatic lesions. Complications occurred in only 14 (6.2%), the most common being self-limited bleeding, which occurred in 12 (85.7%) of the 14. The occurrence of complications was not found to be significantly associated with the lesion location, age of the patient, presence of comorbidities, use of a supplementary technique, vascularization pattern, or proximity of the lesion to large vessels. The pathology findings were sufficient for making the diagnosis in 202 cases (89.8%), and the diagnosis was consistent with the clinical suspicion in 132 (58.6%).

Conclusion

The procedure demonstrated a high (approximately 90%) rate of providing a sufficient sample for the diagnosis and a low complication rate, the most common complication being self-limiting bleeding.

Contrast-enhanced ultrasound (CEUS) in abdominal intervention

The introduction of ultrasound contrast agents has rendered contrast-enhanced ultrasound (CEUS) a valuable complementary technique to address clinically significant problems. This pictorial review describes the use of CEUS guidance in abdominal intervention and illustrates such application for a range of clinical indications. Clinical application of CEUS discussed include commonly performed abdominal interventional procedures, such as biopsy, drainage, nephrostomy, biliary intervention, abdominal tumor ablation and its subsequent monitoring, and imaging of vascular complications following abdominal intervention. The purpose of this article is to further familiarize readers with the application of CEUS, particularly its specific strength over alternative imaging modalities, in abdominal intervention.

Using needle orientation sensing as surrogate signal for respiratory motion estimation in percutaneous interventions

PURPOSE

To develop and evaluate an approach to estimate the respiratory-induced motion of lesions in the chest and abdomen.

MATERIALS AND METHODS

The proposed approach uses the motion of an initial reference needle inserted into a moving organ to estimate the lesion (target) displacement that is caused by respiration. The needles position is measured using an inertial measurement unit (IMU) sensor externally attached to the hub of an initially placed reference needle. Data obtained from the IMU sensor and the target motion are used to train a learning-based approach to estimate the position of the moving target. An experimental platform was designed to mimic respiratory motion of the liver. Liver motion profiles of human subjects provided inputs to the experimental platform. Variables including the insertion angle, target depth, target motion velocity and target proximity to the reference needle were evaluated by measuring the error of the estimated target position and processing time.

RESULTS

The mean error of estimation of the target position ranged between 0.86 and 1.29 mm. The processing maximum training and testing time was 5 ms which is suitable for real-time target motion estimation using the needle position sensor.

CONCLUSION

The external motion of an initially placed reference needle inserted into a moving organ can be used as a surrogate, measurable and accessible signal to estimate in real-time the position of a moving target caused by respiration; this technique could then be used to guide the placement of subsequently inserted needles directly into the target.

Evaluation of the clinical benefit of an electromagnetic navigation system for CT-guided interventional radiology procedures in the thoraco-abdominal region compared with conventional CT guidance (CTNAV II): study protocol for a randomised controlled trial

BACKGROUND

Interventional radiology includes a range of minimally invasive image-guided diagnostic and therapeutic procedures that have become routine clinical practice. Each procedure involves a percutaneous needle insertion, often guided using computed tomography (CT) because of its availability and usability. However, procedures remain complicated, in particular when an obstacle must be avoided, meaning that an oblique trajectory is required. Navigation systems track the operator's instruments, meaning the position and progression of the instruments are visualised in real time on the patient's images. A novel electromagnetic navigation system for CT-guided interventional procedures (IMACTIS-CT®) has been developed, and a previous clinical trial demonstrated improved needle placement accuracy in navigation-assisted procedures. In the present trial, we are evaluating the clinical benefit of the navigation system during the needle insertion step of CT-guided procedures in the thoraco-abdominal region.

METHODS/DESIGN

This study is designed as an open, multicentre, prospective, randomised, controlled interventional clinical trial and is structured as a standard two-arm, parallel-design, individually randomised trial. A maximum of 500 patients will be enrolled. In the experimental arm (navigation system), the procedures are carried out using navigation assistance, and in the active comparator arm (CT), the procedures are carried out with conventional CT guidance. The randomisation is stratified by centre and by the expected difficulty of the procedure. The primary outcome of the trial is a combined criterion to assess the safety (number of serious adverse events), efficacy (number of targets reached) and performance (number of control scans acquired) of navigation-assisted, CT-guided procedures as evaluated by a blinded radiologist and confirmed by an expert committee in case of discordance. The secondary outcomes are (1) the duration of the procedure, (2) the satisfaction of the operator and (3) the irradiation dose delivered, with (4) subgroup analysis according to the expected difficulty of the procedure, as well as an evaluation of (5) the usability of the device.

DISCUSSION

This trial addresses the lack of published high-level evidence studies in which navigation-assisted CT-guided interventional procedures are evaluated. This trial is important because it addresses the problems associated with conventional CT guidance and is particularly relevant because the number of interventional radiology procedures carried out in routine clinical practice is increasing.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01896219 . Registered on 5 July 2013.

In vivo comparison of two navigation systems for abdominal percutaneous needle intervention

PURPOSE

To compare the accuracy of a Kinect-Optical navigation system with an electromagnetic (EM) navigation system for percutaneous liver needle intervention.

MATERIALS AND METHODS

Five beagles with nine artificial tumors were used for validation. The Veran IG4 EM navigation system and a custom-made Kinect-Optical navigation system were used. Needle insertions into each tumor were conducted with these two guidance methods. The target positioning error (TPE) and the time cost of the puncture procedures were evaluated.

RESULTS

A total of 18 needle insertions were performed to evaluate the navigation accuracy of the two guidance approaches. The targeting error was 6.78 ± 3.22 mm and 8.72 ± 3.5 mm for the Kinect-Optical navigation system and the EM navigation system, respectively. There is no statistically significant difference in the TPE between the Kinect-Optical navigation system and the EM navigation system (p = 0.229). The processing time with the Kinect-Optical system (10 min) is similar to that of the Veran IG4 system (12 min).

CONCLUSIONS

The accuracy of the Kinect-Optical navigation system is comparable to that of the EM navigation system.

Contrast-enhanced US-guided Interventions: Improving Success Rate and Avoiding Complications Using US Contrast Agents

Ultrasonography (US) is an established modality for intervention. The introduction of microbubble US contrast agents (UCAs) has the potential to further improve US imaging for intervention. According to licensing, UCAs are currently approved for clinical use in restricted situations, but many additional indications have become accepted as having clinical value. The use of UCAs has been shown to be safe, and there is no risk of renal toxic effects, unlike with iodinated or gadolinium contrast medium. Broadly speaking, UCAs can be injected into the bloodstream (intravascular use) or instilled into almost any accessible body cavity (endocavitary use), either in isolation or synchronously. In microvascular applications, contrast-enhanced US (CEUS) enhances delineation of necrotic areas and the vascularized target to improve real-time targeting. The ability of CEUS to allow true assessment of vascularity has also been used in follow-up of devascularizing intervention. In macrovascular applications, real-time angiographic images can be obtained with CEUS without nephrotoxic effects or radiation. In endocavitary applications, CEUS can achieve imaging similar to that of iodinated contrast medium-based fluoroscopy; follow-up to intervention (eg, tubography and nephrostography) can be performed at the bedside, which may be advantageous. The use of UCAs is a natural progression in US-guided intervention. The aim of this article is to describe the indications, contraindications, and techniques of using UCAs as an adjunctive tool for US-guided interventional procedures to facilitate effective treatment, improve complication management, and increase the overall success of interventional procedures. Online supplemental material is available for this article. ^©RSNA, 2016.

Transbiliary intravascular ultrasound-guided diagnostic biopsy of an inaccessible pancreatic head mass

Percutaneous image-guided biopsies of pancreatic malignancies may prove challenging and nondiagnostic due to a variety of anatomic considerations. For patients with complex post-surgical anatomy, such as a Roux-en-Y gastric bypass, diagnosis via endoscopic ultrasound with fine-needle aspiration may not be possible because of an inability to reach the proximal duodenum. This report describes the first diagnostic case of transbiliary intravascular ultrasound-guided biopsy of a pancreatic head mass in a patient with prior Roux-en-Y gastric bypass for which a diagnosis could not be achieved via percutaneous and endoscopic approaches. Transbiliary intravascular ultrasound-guided biopsy resulted in a diagnosis of pancreatic adenocarcinoma, allowing the initiation of chemotherapy.

Prospective Randomized Trial for Image-Guided Biopsy Using Cone-Beam CT Navigation Compared with Conventional CT

PURPOSE

To compare cone-beam computed tomography (CT) navigation vs conventional CT image guidance during biopsies.

MATERIALS AND METHODS

Patients scheduled for image-guided biopsies were prospectively and randomly assigned to conventional CT guidance vs cone-beam CT navigation. Radiation dose, accuracy of final needle position, rate of histopathologic diagnosis, and number of needle repositions to reach the target (defined as pullback to adjust position) were compared.

RESULTS

A total of 58 patients (mean age, 57 y; 62.1% men) were randomized: 29 patients underwent 33 biopsies with CT guidance and 29 patients with 33 lesions underwent biopsy with cone-beam CT navigation. The average body mass index (BMI) was similar between groups, at 28.8 kg/m(2) ± 6.55 (P = .18). There was no difference between groups in terms of patient and lesion characteristics (eg, size, depth). The average lesion size was 29.1 ± 12.7mm for CT group vs 32.1mm ±16.8mm for cone-beam CT group (P < 0.59). Location of lesions was equally divided between the 2 groups, 20 lung lesions, 18 renal lesions and 20 other abdominal lesions. Mean number of needle repositions in the cone-beam CT group was 0.3 ± 0.5, compared with 1.9 ± 2.3 with conventional CT (P < .001). The average skin entry dose was 29% lower with cone-beam CT than with conventional CT (P < .04 accounting for BMI). The average estimated effective dose for the planning scan from phantom data was 49% lower with cone-beam CT vs conventional CT (P = .018). Accuracy, defined as the difference between planned and final needle positions, was 4.9 mm ± 4.1 for the cone-beam CT group, compared with 12.2 mm ± 8.1 for conventional CT (P < .001). Histopathologic diagnosis rates were similar between groups, at 90.9% for conventional CT and 93.9% for cone-beam CT (P = .67).

CONCLUSIONS

Cone-beam CT navigation for biopsies improved targeting accuracy with fewer needle repositions, lower skin entry dose, and lower effective dose for planning scan, and a comparable histopathologic diagnosis rate.

Preliminary results of ultrasound-guided laser ablation for unresectable metastases to retroperitoneal and hepatic portal lymph nodes

BACKGROUND

Laser ablation with a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser is a minimally invasive approach which is able to achieve a precise tissue necrosis. The study was aimed to assess the feasibility and efficiency of laser ablation in the treatment of retroperitoneal and hepatic portal unresectable metastatic lymph nodes.

METHODS

Eight patients including 11 pathologically proven metastatic lymph nodes, 4 in retroperitoneal, 7 in hepatic portal region, were treated by laser ablation. Primary cancers were cholangiocarcinoma (n = 4) and hepatocellular carcinoma (n = 4). Under sonographic guidance, the laser ablation was performed percutaneously. Follow-up contrast computed tomography or magnetic resonance image was performed.

RESULTS

The treatments were completed in single process in all the patients. No severe complications occurred. Follow-up contrast computed tomography or magnetic resonance imaging at 1 and 3 months showed partial responses in 11 lymph nodes. The local response rate at the 6 month follow-up was 75.0 %. The overall response rate was 62.5 %. Abdominal pain scores decreased significantly in all patients. Tumor marker levels decreased in six patients. The Child-Pugh grade did not change.

CONCLUSIONS

The results suggest that sonographically guided laser ablation is technically feasible for the local treatment of unresectable retroperitoneal and hepatic portal lymph nodes from hepatic cancer. Although further study is needed to evaluate its long time efficacy, abdominal pain relief is prominent.

Kidney, Ureter, and Bladder Biopsy

Percutaneous urologic biopsy is a safe and effective technique and can comprise a significant proportion of the daily workload of the interventional radiologist. This article discusses the indications and rationale for the performance of renal, ureter, and bladder biopsy as well as the approach to performing such biopsies, pitfalls, and potential complications.

Practical dose reduction tips for abdominal interventional procedures using CT-guidance

Reducing the radiation dose should be an endeavor not only for diagnostic CT exams but also for interventional procedures using CT-guidance. Given that interventional procedures vary in scope and complexity, there is greater variability in radiation doses delivered during CT procedures. The goal in an interventional procedure is simply to advance the interventional instruments into the target lesions, and as such diagnostic level doses are not required and only narrow scan range scans need to be acquired. Adherence to the principles outlined in this article will allow such procedures to be performed with reduced radiation doses.

Percutaneous biopsy in the abdomen and pelvis: a step-by-step approach

Percutaneous abdominal biopsies provide referring physicians with valuable diagnostic and prognostic information that guides patient care. All biopsy procedures follow a similar process that begins with the preprocedure evaluation of the patient and ends with the postprocedure management of the patient. In this review, a step-by-step approach to both routine and challenging abdominal biopsies is covered with an emphasis on the differences in biopsy devices and imaging guidance modalities. Adjunctive techniques that may facilitate accessing a lesion in a difficult location or reduce procedure risk are described. An understanding of these concepts will help maintain the favorable safety profile and high diagnostic yield associated with percutaneous biopsies.

Difficult biopsy and drainage: just say yes

Abdominal radiologists are often asked to perform difficult percutaneous chest, abdomen, and pelvis biopsies and drainages with imaging guidance. Many of these procedures involve small target lesions far from the skin surface, in close proximity to critical structures. Organ location is changeable due to respiration, peristalsis, and pulsation, further complicating the planning process. High-level three-dimensional spatial awareness is critical to mastery of complex image-guided procedures. A comprehensive grasp of anatomy and expected changes can be exploited in certain cases to target lesions within a solid organ or to avoid injury to sensitive structures during biopsy, drain placement, or thermal ablation. In this article, we will use illustrative cases to explore the use of anatomic knowledge and the ability to synthesize this three-dimensional data dynamically during planning and execution of difficult CT- and ultrasound-guided procedures. We will discuss unusual biopsy requests-such as bowel biopsies-and the benefits of using ultrasound guidance for certain procedures in the chest. Additionally, we will describe multiple special techniques, including out of standard plane angulation and endocavitary techniques, in order to maximize chances of success.

Chronic inflammation masquerading as an appendiceal tumour with peritoneal metastasis: the challenge of diagnosis and the lessons learnt

Advanced radiological imaging has largely replaced exploratory operations and has become an essential diagnostic tool clinicians routinely rely on. However, physicians are faced with a lot of radiological findings without histological proof, and assuming a more serious diagnosis may lead to unnecessary investigations and emotional stress for patients. We report an unusual presentation of chronic appendicitis with a synchronous peritoneal nodule on CT in a 76-year-old woman who presented with poor appetite, weight loss and a mass in the right iliac fossa. The coincidental finding of the nodule in addition to the suspicious appearance of the appendix raised concerns for primary appendiceal cancer with peritoneal metastasis. The case illustrates the patient's management and reflects on the learnt lessons with regard to careful use of invasive radiology-guided biopsies and interval imaging, as these could sometimes delay the diagnosis and management of a readily treatable disease.

Body-mounted robotic instrument guide for image-guided cryotherapy of renal cancer

PURPOSE

Image-guided cryotherapy of renal cancer is an emerging alternative to surgical nephrectomy, particularly for those who cannot sustain the physical burden of surgery. It is well known that the outcome of this therapy depends on the accurate placement of the cryotherapy probe. Therefore, a robotic instrument guide may help physicians aim the cryotherapy probe precisely to maximize the efficacy of the treatment and avoid damage to critical surrounding structures. The objective of this paper was to propose a robotic instrument guide for orienting cryotherapy probes in image-guided cryotherapy of renal cancers. The authors propose a body-mounted robotic guide that is expected to be less susceptible to guidance errors caused by the patient's whole body motion.

METHODS

Keeping the device's minimal footprint in mind, the authors developed and validated a body-mounted, robotic instrument guide that can maintain the geometrical relationship between the device and the patient's body, even in the presence of the patient's frequent body motions. The guide can orient the cryotherapy probe with the skin incision point as the remote-center-of-motion. The authors' validation studies included an evaluation of the mechanical accuracy and position repeatability of the robotic instrument guide. The authors also performed a mock MRI-guided cryotherapy procedure with a phantom to compare the advantage of robotically assisted probe replacements over a free-hand approach, by introducing organ motions to investigate their effects on the accurate placement of the cryotherapy probe. Measurements collected for performance analysis included accuracy and time taken for probe placements. Multivariate analysis was performed to assess if either or both organ motion and the robotic guide impacted these measurements.

RESULTS

The mechanical accuracy and position repeatability of the probe placement using the robotic instrument guide were 0.3 and 0.1 mm, respectively, at a depth of 80 mm. The phantom test indicated that the accuracy of probe placement was significantly better with the robotic instrument guide (4.1 mm) than without the guide (6.3 mm, p<0.001), even in the presence of body motion. When independent organ motion was artificially added, in addition to body motion, the advantage of accurate probe placement using the robotic instrument guide disappeared statistically [i.e., 6.0 mm with the robotic guide and 5.9 mm without the robotic guide (p = 0.906)]. When the robotic instrument guide was used, the total time required to complete the procedure was reduced from 19.6 to 12.7 min (p<0.001). Multivariable analysis indicated that the robotic instrument guide, not the organ motion, was the cause of statistical significance. The statistical power the authors obtained was 88% in accuracy assessment and 99% higher in duration measurement.

CONCLUSIONS

The body-mounted robotic instrument guide allows positioning of the probe during image-guided cryotherapy of renal cancer and was done in fewer attempts and in less time than the free-hand approach. The accuracy of the placement of the cryotherapy probe was better using the robotic instrument guide than without the guide when no organ motion was present. The accuracy between the robotic and free-hand approach becomes comparable when organ motion was present.

Hydrodissection-assisted image-guided percutaneous biopsy of abdominal and pelvic lesions: experience with seven patients

OBJECTIVE

The purpose of this study was to evaluate the effectiveness of retroperitoneal organ displacement for image-guided percutaneous biopsy.

CONCLUSION

Organ displacement using 0.9% saline or 5% dextrose in water (D5W) can create safe access routes for targeted abdominal and pelvic biopsies.

Initial Experience of Utilizing Real-Time Intra-Procedural PET/CT Biopsy

OBJECTIVES

Nonreal-time Positron Emission Tomography/Computed Tomography (PET/CT) biopsies that use the image co-registration of a prior PET with an intra-procedural CT have been reported. The aim of this study was to report the initial experience of performing real-time intra-procedural PET/CT-guided biopsies.

MATERIALS AND METHODS

All patients (n = 4) had a prior PET/CT examination of the concerning lesion and no significant CT correlate. On the day of the biopsy, 5 mCi of 18F-fluorodeoxyglucose (FDG) or NaF18 was intravenously injected. After 60 min of biodistribution of the molecular probe, PET/CT images were obtained in a limited one bed position over the region of the concerning lesion to be biopsied.

RESULTS

One patient had a mesenteric mass and the other three had bone lesions, one located in the rib and two in the iliac bone. The pathology report revealed that two lesions (50%) were malignant and two lesions (50%) were benign. The results of the biopsy changed management in all cases. There was 0% complication rate.

CONCLUSIONS

No additional software or hardware is required to perform real-time intra-procedural PET/CT-guided biopsies. It can optimize the yield, especially in cases where there are no anatomical abnormalities. Real-time intra-procedural PET/CT biopsy may have benefits over conventional biopsy techniques in terms of accuracy.

Trans-organ versus trans-mesenteric computed tomography-guided percutaneous fine-needle aspiration biopsy of pancreatic masses: feasibility and safety

AIM

To evaluate the safety and efficacy of computed tomography (CT)-guided percutaneous fine-needle aspiration biopsy (FNAB) of pancreatic masses that traverses the gastrointestinal tract or solid viscera.

MATERIALS AND METHODS

From January 2002 to December 2012, 144 patients underwent 165 CT-guided biopsies of pancreatic masses. Biopsies were performed using a 21 or 22 G needle. Cytology reports, medical records, and procedure details for all patients were retrospectively reviewed to evaluate the biopsy route, complications, and diagnostic accuracy.

RESULTS

Trans-organ biopsies of pancreatic masses were safely performed via a direct pathway traversing the stomach (n = 45), colon (n = 14), jejunum (n = 4), or liver (n = 5). There were five self-limiting mesenteric haematomas along the biopsy route on immediate post-procedure CT and all patients remained asymptomatic. All haematomas occurred after a trans-mesenteric approach rather than passage through abdominal organs. Three patients had acute pancreatitis. There was no significant difference in complications and diagnostic yields between the groups. The sensitivity, specificity, positive predictive value, and negative predictive value of final FNAB cytology for malignancy were 98.3%, 100%, 100% and 71.4%, respectively. The overall accuracy was 98.4%.

CONCLUSION

Percutaneous FNAB using the trans-organ approach is a safe and effective technique to diagnose pancreatic malignancy.

Radiation dose optimization for CT-guided interventional procedures in the abdomen and pelvis

Radiation dose to patients can be high for some CT-guided interventional procedures in the abdomen and pelvis, especially tumor ablations. Strategies for radiation dose reduction include choosing an alternative guidance modality that does not use radiation whenever feasible, restricting the cranio-caudal length of interventional scans to the interventional target, and refinement of technical skills in order to minimize the number of scans acquired for interventional guidance. Dose optimization for these procedures is best achieved by lowering the tube current relative to the prior diagnostic scan, choosing dose efficient scanning modes, and using intermittent-mode, narrowly collimated CT fluoroscopy for interventional guidance.