Timothy E. Murray

Evaluation of a novel 2D perfusion angiography technique independent of pump injections for assessment of interventional treatment of peripheral vascular disease

To evaluate a novel 2D-perfusion angiography (2D-PA) technique allowing pro- and retrospective flow analysis based on a proximal reference region of interest (ROI) and distal target ROI in patients treated for peripheral arterial disease. 2D-PA allows quantifying blood flow by post-processing of digital subtraction angiography (DSA). 2D-PA was performed pre and post interventional treatment of peripheral arterial disease (PAD; n = 24; 13 angioplasties, 11 stents) in 21 patients (17 men, 72 ± 9y) with Fontaine stage IIB / III. Time-to-peak (TTP), peak density (PD) and area-under-the-curve (AUC) were calculated. Ratios reference/target ROI (TTPOUTFLOW/TTPINFLOW; PDOUTFLOW/PDINFLOW; AUCOUTFLOW/AUCINFLOW) were calculated and correlated to changes in the ankle-brachial-index (ABI). 2D-PA was technically feasible in all cases. A significant increase in ABI was seen after interventional treatment (+39%; p < 0.0001). ABI increase was accompanied by an increase of 36% of PDOUTFLOW/PDINFLOW (p < 0.0001), a 52% decrease of TTPOUTFLOW/TTPINFLOW (p = 0.0007) and a 69% increase of AUCOUTFLOW/AUCINFLOW (p < 0.0001). The difference of TTP pre- and post-intervention showed a correlation with the difference in ABI (r = −0.53, p = 0.0081). The other measured parameters failed to demonstrate significant correlation with improved ABI. The presented 2D-PA technique allows quantitative assessment of arterial flow before, during and after interventional treatment in PAD.

Two-Dimensional Perfusion Angiography of the Foot Technical Considerations and Initial Analysis

Purpose: To report the feasibility, technical considerations, and initial results of 2-dimensional (2D) perfusion angiography of the foot before and after endovascular interventions. Methods: A retrospective single-center study involved 21 patients (mean age 73.4±10.5 years; 14 men) with severe peripheral vascular disease [Fontaine stage III (n=10) or IV (n=14)] who underwent lower limb digital subtraction angiography (DSA) prior to and following endovascular treatment of above- and/or below-knee lesions. A standardized contrast administration protocol (15 mL iodixanol 320 mg I/mL at 3 mL/s via a 5/6-F antegrade sheath) was applied during DSA using a 2D perfusion–enabled image intensifier. Representative hindfoot and forefoot regions of interest were analyzed, and representative numeric density values [time to peak (TTP), peak density value (PDV), and area under the (time-density) curve (AUC)] were calculated using 2D perfusion–enabled angiographic software to assess foot perfusion. Values were compared before and after angioplasty and by level of treatment (above or below knee). The parameters were correlated with disease severity (stenosis vs occlusion) and symptom level (Fontaine stage). Results: A clinically significant improvement (29.4%) in the AUC was noted following angioplasty, reaching statistical significance within the hindfoot (p=0.03). No significant change in TTP or PDV was detected following angioplasty. Foot movement remained problematic when measuring time-density values. No statistical difference in perfusion values was appreciable between above- and below-knee angioplasty. Conclusion: Two-dimensional perfusion angiography of the foot allows quantitative evaluation using various density values with potential benefit for treatment planning and technical outcome analysis. Methodical restrictions currently remain, mainly regarding patient movement.

Erratum to: Osteoporosis, obesity, and sarcopenia on abdominal CT: a review of epidemiology, diagnostic criteria, and management strategies for the reporting radiologist

Abdominal computed tomography (CT) is a widely performed examination, with many indications. Assessment of bone, fat, and muscle on abdominal CT can be performed in a quantitative manner. Published studies have developed diagnostic cutoffs for osteoporosis, obesity, and sarcopenia, which are summarized with pictorial examples. The epidemiological and prognostic significance of these disease states are outlined. Further diagnostic steps and treatment strategies are outlined to inform both the managing clinician and reporting radiologist. This article summarizes an unglamorous yet information-rich field, which is ripe for assessment in the dawning era of personalized medicine, and one in which the radiologist is well placed to add value to patient care.

Venous Access Principles and Devices (PICC, Vascular Access Ports and Tunneled Catheters)

Venous access is a mainstay of hospital-based patient treatment, and is increasingly used in community-based treatment. Peripheral venous cannulae have a short lifespan. In addition, the limited gauge of smaller peripheral veins reduces permissible flow rates. As such, these small, low-flow vessels are more prone to venous sclerosis from certain intravenous medications and other substances compared to larger, high-flow veins. Central venous access is indicated in patients who require intermediate-long term access for treatment such as antibiotics, chemotherapy and haemodialysis. The choice of access site and type of vascular access device depends on the clinical indication, expected duration of treatment and patient status. A variety of device types are available which vary in terms of size, lumen number, catheter length, material, coating and termination (hub, port reservoir, etc.). These are tailored to the patient and the clinical indication. Additionally, some catheter designs feature both anti-microbial and heparin-impregnated materials which have additional benefits. Common venous access sites for catheter insertion include the internal jugular and femoral veins. The basilic, cephalic and brachial veins in the arm are also commonly used for placement of peripherally-inserted central catheters (PICC).

Image Guided Biopsies

Image-guided biopsy is widely performed in all organ systems for tissue sampling, either of abnormal tissue that has been identified, or indiscriminate biopsy in cases of organ dysfunction to obtain representative tissue for histological diagnosis. The use of real-time image guidance allows targeted biopsy of even small lesions, and the avoidance of adjacent organs, vessels or collecting systems. The most commonly employed imaging modality is ultrasound, which is ideal for superficial organs like the thyroid, or solid organs such as the liver or kidneys. In addition, special ultrasound probes used transrectally, transvaginally, or endoscopically allow the biopsy of lesions within genitourinary, gastrointestinal and respiratory tracts. Ultrasound is limited by poor transmission of sound waves through air and bone however. CT gives excellent visualisation of structures within aerated lung, bone, and where loops of air-filled bowel are located. This permits biopsy of lung, bone or structures deep within the abdomen or pelvis. Fluoroscopy may also be used for bone biopsy. Other techniques such as MRI or PET guided biopsy are performed on occasion, however are limited by availability and cost. The risks of biopsy depend on systemic factors such as coagulopathy, and regional factors such as adjacent organs with can be inadvertently injured. In addition, certain specific malignant lesions carry a risk of seeding along the biopsy tract, such as osteosarcomas and certain salivary gland tumours. Where such lesions are within the differential diagnosis, biopsy should be planned in conjunction with the relevant oncological surgeon to ensure the biopsy tract will be included in any primary oncological resection, thus preventing the need for additional resection. Where multiple lesions exist, such as in cases of suspected metastatic malignancy, biopsy should target the lowest-risk area, such as superficial lymph nodes. Occasionally, dedifferentiated cytology within distant metastases may necessitate additional biopsies for definitive identification of the primary tumour. The size and number of biopsy cores required vary with organ and local practice. Biopsies of solid organs such as the liver and kidney are typically performed with 16–20 G core needles, with smaller gauge needles often requiring additional cores. Certain lesions such as in the parotid or thyroid may only require fine needle aspiration for diagnosis. Traditionally, a diagnosis of lymphoma required a surgical excision of a node, however there is increasing acceptance of image-guided biopsy in the first instance (Figs. 14.1 and 14.2).

Combining Ultrasound-Guided Vascular Access With Ultrasound-Guided Analgesia for Single Skin and Vessel Puncture:

Purpose: To describe a single skin puncture technique combining subcutaneous injection of anesthetic to the depth of the vessel wall with venipuncture in the same movement. Technique: Using ultrasound guidance, controlled anesthetic instillation along the needle tract and outer vessel wall with a 21-G vascular access needle can be combined with vessel puncture. This technique reduces the number of skin punctures and ensures accurate anesthetic instillation. The maximum inadvertent intravascular dose of commercial local anesthetic preparations that can be delivered with a small syringe is far below toxicity thresholds. Conclusion: A technique for combining anesthetic administration and vascular access with a 21-G needle and ultrasound guidance is feasible.

Pragmatic considerations for medical imaging of the obese patient

Dear Editor, In contemporary clinical practice, we increasingly encounter severely obese (BMI 35–39.9), morbidly obese (BMI 40– 49.9), and super obese (BMI >50) patients. Beyond increased care requirements, this cohort of patients poses additional infrastructural challenges to hospitals. This may be particularly problematic in the performance of medical imaging, where specific modalities pose technical and mechanical challenges. Computed tomography (CT) consists of a mechanical table, which moves the patient through a fixed ring (or gantry). The maximum table weight limit is vendor-specific, but typically 180–210 kg. Above such weights, the table is at risk of breaking which may harm patients. Tables are routinely tested to four times the stated maximal weight, so individual discretion may be employed where necessary [1]. In addition to weight, CT studies are also be limited by gantry diameter. CT gantry diameter is typically 70 cm, equating to a circumference of 220 cm. As patients tend to be elliptical in crosssectional shape (as opposed to a perfect circle), and waist measurements beyond 200 cm are likely to be problematic. Magnetic resonance imaging (MRI) suffers from even more pronounced spatial limitations, due to technical factors demanding maximal magnet field strength, and minimizing distances to patients. Maximal weights are commonly between 150 and 180 kg, slightly less than CT. A typical MRI aperture diameter is 60 cm, smaller than that of CT. BWidebore^ machines are available with a similar but more capacious design, with larger apertures up to 70 cm. BOpen-bore^ scanners are available, with two flat magnets positioned parallel, although their lower magnet strength limits image quality. It should be noted that for both CT and MRI, extremities such as the limbs and head may be placed in the aperture without the remaining body, thus circumventing diameters; however, the table weight restrictions may still apply. Ultrasound (US) is often performed in the patient’s own bed and, thus, is not subject to weight restrictions. US is associated with unique technical limitations however. Softtissue adiposity reflects a high proportion of sound waves, accounting for its bright appearance of fat on sonography. With a standard abdominal probe (3–7 MHz), 50% of the beam intensity (watts/cm) is attenuated with every 1 cm of fat traversed. In an obese patient with 8 cm of subcutaneous abdominal fat, 94% of sound waves are reflected prior to the peritoneal layer of the abdominal wall [1]. This renders imaging of deeper structures challenging, due to the lack of penetrating sound waves. The use of low-frequency probes increases penetration, and additional processing techniques on newer machines (such as tissue-harmonics) can enhance resolution. In nuclear medicine, it is possible to position a flat gamma camera directly over the patient in their own bed to obtain planar images. However, newer SPECT-CT and PET-CT systems have a circular gantry similar to CT or MRI for hybrid image acquisition, thus requiring the patient to use the fixed mechanical table, and are consequently associated with diameter and weight restrictions similar to CT and MRI systems. Interventional radiology and screening tables are usually unrestricted by patient circumference, as the flat detectors can be moved up and down. They do require the patient to be positioned on the mechanical table and are therefore associated with weight restrictions. Maximal weights are vendorspecific, but typically range from 150 to 180 kg. The specific model of scanner or imaging system used in any hospital is generally displayed on all studies in the top * T. É Murray timothymurray@rcsi.ie

Comparative diagnostic test accuracy of post-esophagectomy water-soluble computed tomography and fluoroscopic swallow studies: A meta-analysis

Aims: Both fluoroscopic water-soluble contrast swallow (FWSCS) and CT water-soluble contrast swallow (CTWSCS) are widely performed as a routine in the post-esophagectomy patient to assess for anastomotic leak. Several prospective studies have compared FWSCS and CTWSCS; however, no synthesis of the data exists. Materials and Methods: Systematic review and meta-analysis of diagnostic test accuracy studies comparing FWSCS and CTWSCS in the adult patient following esophagectomy for malignancy was performed in accordance with PRISMA guidelines. Results: Three diagnostic test accuracy studies met the inclusion criteria, directly comparing FWSCS and CTWSCS in 185 patients. FWSCS demonstrated high specificity (98%), but low sensitivity (64%). CTWSCS can be categorized as normal, mediastinal gas without contrast leak, or leakage of oral contrast. Visible leakage of oral contrast demonstrated high specificity (98%) but low sensitivity (56%). The presence of mediastinal gas increased sensitivity (84%), but reduced specificity (85%). The higher sensitivity of CTWSCS over FWSCS failed to reach significance (P = 0.125). Conclusion: CTWSCS shares the high specificity of FWSCS. Its higher sensitivity increases its utility as a rule-out test in the postoperative period. Additional factors that may influence decision-making are described.

Prevalence of Incidental Findings on Multidetector Computed Tomography in Potential Nephrectomy Donors: A Prospective Observational Study

OBJECTIVES Prospective renal donors are a select population of healthy individuals who have been thoroughly screened for significant comorbidities before they undergo multidetector computed tomography. Our aim was to determine the prevalence of incidental findings on preoperative multidetector computed tomography in a healthy cohort of potential living donors for kidney transplant. MATERIALS AND METHODS A prospective study was performed of prospective living kidney transplant donors at a national kidney transplant center. Study inclusion criteria were all potential kidney donors who underwent multidetector computed tomography during the living-donor assessment process over a 5-year period (January 2012 to 2017). RESULTS Our cohort included 375 potential living donors who had multidetector computed tomography; mean age was 44.33 years (range, 21-71.5 y). In total, there were 228 incidental findings identified in 158 individuals. Of the 375 potential donors, 193 (51%) proceeded to living donor nephrectomy. On multidetector computed tomography, 97 incidental findings were identified in the donor cohort versus 131 in the cohort that did not proceed to donation. Bosniak 1 renal cysts were the most common incidental finding (n = 46) followed by liver cysts < 1.5 cm (n = 42) and urinary tract calculi (n = 21). There was 1 incidentally detected pathologically proven malignancy. CONCLUSIONS A variety of incidentally detected lesions of moderate to high importance were detected in this healthy donor cohort. Individuals undergoing assessment with multidetector computed tomography for living donor nephrectomy should be counseled on medical, financial, and psychological implications of incidentally detected lesions during the kidney transplant evaluation process.

Are We Overtreating Renal Angiomyolipoma: A Review of the Literature and Assessment of Contemporary Management and Follow-Up Strategies

Renal angiomyolipoma (AML) are benign tumours composed of fat, muscle, and disorganised blood vessels. Historic treatment algorithms for sporadic AML based on size fail to consider additional risk factors such as tumour vascularity and pseudoaneurysm formation. As AML is now predominantly incidental, rupture is rare and its mortality low. The recent publication of the largest longitudinal series to date also suggest that growth is uncommon, challenging existing surveillance paradigms. The evidence assessing treatment strategies in AML are reviewed, with particular emphasis on incidental sporadic AML. The relative merits of various AML treatments are discussed, and areas of clinical uncertainty highlighted.