Alexander S. Pasciak

Comments on "evaluation of a Noise Reduction Imaging Technology in Iliac Digital Subtraction Angiography: Noninferior Clinical Image Quality with Lower Patient and Scatter Dose"

2. Ikeda O, Nakasone Y, Beppu T, Masuda T, Baba H, Yamashita Y. Selective embolization of the splenic vein for shunt-preserving disconnection of the portal and systemic circulation: report of two cases. Acta Radiol Short Rep 2012;1. 3. Inoue M, Tanaka T, Nakagawa H, Yoshioka T, Kichikawa K. Splenic Vein embolization using coil anchors and prophylactic occlusion of a hepatofugal collateral for hepatic encephalopathy due to splenorenal shunt: technical note and literature review. Case Rep Radiol 2013; 2013:160653. 4. Rogal SS, Hu A, Bandi R, Shaikh O. Novel therapy for non-cirrhotic hyperammonemia due to a spontaneous splenorenal shunt. World J Gastroenterol 2014; 20:8288–8291.

The evolution of image-guided lumbosacral spine surgery

Techniques and approaches of spinal fusion have considerably evolved since their first description in the early 1900s. The incorporation of pedicle screw constructs into lumbosacral spine surgery is among the most significant advances in the field, offering immediate stability and decreased rates of pseudarthrosis compared to previously described methods. However, early studies describing pedicle screw fixation and numerous studies thereafter have demonstrated clinically significant sequelae of inaccurate surgical fusion hardware placement. A number of image guidance systems have been developed to reduce morbidity from hardware malposition in increasingly complex spine surgeries. Advanced image guidance systems such as intraoperative stereotaxis improve the accuracy of pedicle screw placement using a variety of surgical approaches, however their clinical indications and clinical impact remain debated. Beginning with intraoperative fluoroscopy, this article describes the evolution of image guided lumbosacral spinal fusion, emphasizing two-dimensional (2D) and three-dimensional (3D) navigational methods.

How Sensitive Is the Upper Gastrointestinal Tract to 90Y Radioembolization? A Histologic and Dosimetric Analysis in a Porcine Model

In 90Y radioembolization, nontarget embolization to the stomach or small bowel can result in gastrointestinal injury, a rare but difficult to manage clinical complication. However, dosimetric thresholds for toxicity to these tissues from radioembolization have never been evaluated in a controlled setting. We performed an analysis of the effect of 90Y radioembolization in a porcine model at different absorbed-dose endpoints. Methods: Six female pigs underwent transfemoral angiography and infusion of 90Y-resin microspheres into arteries supplying part of the gastric wall. Esophagogastroduodenoscopy was performed after 4 wk to assess interim gastrointestinal health. Animals were monitored for side effects for 9 wk after 90Y infusion, after which they were euthanized and their upper gastrointestinal tracts were excised for analysis. Histologic sections were used to map microsphere location, and a microdosimetric evaluation was performed to determine the absorbed-dose profile within the gastrointestinal wall. Results: 90Y radioembolization dosages from 46.3 to 105.1 MBq were infused, resulting in average absorbed doses of between 35.5 and 91.9 Gy to the gastric wall. No animal exhibited any signs of pain or gastrointestinal distress through the duration of the study. Excised tissue showed 1–2 small (<3.0 cm2) healed or healing superficial gastric lesions in 5 of 6 animals. Histologic analysis demonstrated that lesion location was superficial to areas of abnormally high microsphere deposition. An analysis of microsphere deposition patterns within the gastrointestinal wall indicated a high preference for submucosal deposition. Dosimetric evaluation at the luminal mucosa performed on the basis of microscopic microsphere distribution confirmed that 90Y dosimetry techniques conventionally used in hepatic dosimetry provide a first-order estimate of absorbed dose. Conclusion: The upper gastrointestinal tract may be less sensitive to 90Y radioembolization than previously thought. Lack of charged-particle equilibrium at the luminal mucosa may contribute to decreased toxicity of 90Y radioembolization compared with external-beam radiation therapy in gastrointestinal tissue. Clinical examples of injury from 90Y nontarget embolization have likely resulted from relatively large 90Y activities being deposited in small tissue volumes, resulting in absorbed doses in excess of 100 Gy.

Sensitivity of the diagnostic radiological index of protection to procedural factors in fluoroscopy

PURPOSEnTo evaluate the sensitivity of the diagnostic radiological index of protection (DRIP), used to quantify the protective value of radioprotective garments, to procedural factors in fluoroscopy in an effort to determine an appropriate set of scatter-mimicking primary beams to be used in measuring the DRIP.nnnMETHODSnMonte Carlo simulations were performed to determine the shape of the scattered x-ray spectra incident on the operator in different clinical fluoroscopy scenarios, including interventional radiology and interventional cardiology (IC). Two clinical simulations studied the sensitivity of the scattered spectrum to gantry angle and patient size, while technical factors were varied according to measured automatic dose rate control (ADRC) data. Factorial simulations studied the sensitivity of the scattered spectrum to gantry angle, field of view, patient size, and beam quality for constant technical factors. Average energy (Eavg) was the figure of merit used to condense fluence in each energy bin to a single numerical index.nnnRESULTSnBeam quality had the strongest influence on the scattered spectrum in fluoroscopy. Many procedural factors affect the scattered spectrum indirectly through their effect on primary beam quality through ADRC, e.g., gantry angle and patient size. Lateral C-arm rotation, common in IC, increased the energy of the scattered spectrum, regardless of the direction of rotation. The effect of patient size on scattered radiation depended on ADRC characteristics, patient size, and procedure type.nnnCONCLUSIONSnThe scattered spectrum striking the operator in fluoroscopy is most strongly influenced by primary beam quality, particularly kV. Use cases for protective garments should be classified by typical procedural primary beam qualities, which are governed by the ADRC according to the impacts of patient size, anatomical location, and gantry angle.

Bariatric Radioembolization: A Pilot Study on Technical Feasibility and Safety in a Porcine Model

PURPOSEnTo evaluate feasibility of left gastric artery (LGA) yttrium-90 ((90)Y) radioembolization as potential treatment for obesity in a porcine model.nnnMATERIALS AND METHODSnThis study included 8 young female pigs (12-13 weeks, 21.8-28.1 kg). Six animals received infusions of (90)Y resin microspheres (46.3-105.1 MBq) into the main LGA and the gastric artery arising from the splenic artery. Animal weight and serum ghrelin were measured before treatment and weekly thereafter. Animals were euthanized 69-74 days after treatment, and histologic analyses of mucosal integrity and ghrelin immunoreactive cell density were performed.nnnRESULTSnSuperficial mucosal ulcerations < 3.0 cm(2) were noted in 5 of 6 treated animals. Ghrelin immunoreactive cell density was significantly lower in treated versus untreated animals in the stomach fundus (13.5 vs 34.8, P < .05) and stomach body (11.2 vs 19.8, P < .05). Treated animals gained less weight than untreated animals over the study duration (40.2 kg ± 5.4 vs 54.7 kg ± 6.5, P = .053). Average fundic parietal area (165 cm(2) vs 282 cm(2), P = .067) and average stomach weight (297.2 g vs 397.0 g, P = .067) were decreased in treated versus untreated animals. Trichrome staining revealed significantly more fibrosis in treatment animals compared with control animals (13.0 vs 8.6, P < .05). No significant differences were identified in plasma ghrelin concentrations (P = .24).nnnCONCLUSIONSnLGA (90)Y radioembolization is promising as a potential treatment for obesity. A larger preclinical study is needed to evaluate the safety and efficacy of this procedure further.

Time to take the gloves off: the use of radiation reduction gloves can greatly increase patient dose

Sterile radiation reduction gloves have been widely used over the past several decades in an effort to reduce hand doses during fluoroscopically guided procedures. While multiple studies have quantified the potential dose reduction to the fluoroscope operator from the use of such gloves, possible effects on the patient have not yet been quantified. The aim of this study was to examine the impact on patient dose when radiation reduction gloves are used. The impact on patient dose when using radiation reduction gloves in the field of view (FOV) was evaluated by measuring patient entrance surface dose rates (ESDR) using three C‐arm fluoroscopes for a range of patient sizes and different operating and magnification modes. Multiple measuring fields were used in combination with both peripheral and central glove placement. ESDR were measured with no glove in the FOV, with one radiation reduction glove, and with double gloves in the FOV, to replicate the actions of some fluoroscope operators. Compared to an ungloved hand, the use of a single radiation reduction glove in the measuring field resulted in up to a 2.8‐fold increase in ESDR. The use of double radiation reduction gloves resulted in up to a 4.9‐fold increase in ESDR. In both cases, the increase in ESDR was dependent on the size of the patient and on the operating and magnification modes used, and ranged from no increase up to the aforementioned maximum. When used in the FOV, and particularly within the measuring field, radiation reduction gloves can substantially increase ESDR. This increase in dose, when considered against the relatively small published reduction in dose to the operators hands, may mean that the increased risks from the use of radiation reduction gloves outweigh the benefits. In any case, hands should not be placed in the FOV if not required by the goals of the procedure. PACS number: 87.59.C‐

SU‐E‐I‐175: Evaluation of Quantitative Direct PET/CT Imaging of Y‐90 Microspheres Using the Jaszczak Phantom

Purpose: Selective internal radiation therapy (SIRT) of liver metastases and hepatocellular carcinoma with radiolabeled microspheres has become a viable treatment modality in recent years. This technique uses the high‐ energy, pure beta‐emitting radioisotope of yttrium‐90 (Y‐90) embedded in a glass or resin microsphere which is infused into the liver via the hepatic artery. However, direct imaging the post‐infusion distribution of Y‐90 SIRT has been a long standing problem due to the lack of any gamma emission. Recently, however, a low‐yield branch of Y‐90 decaying by internal pair‐ production was used to perform direct PET/CT coincidence imaging. With only a few publications summarizing preliminary clinical results, we have designed a quantitative phantom analysis allowing for a detailed and portable image quality and quantitation evaluation of this new imaging technique. Methods: Owing to its wide availability, the Jaszczak PETimaging phantom is an ideal choice for Y‐90 PET/CT imaging evaluation with a few minor modifications. As the Jaszczak phantom is water filled, a major difficulty is the fast settling of the microspheres, which stay in uniform suspension for less than one minute. An aqueous linear polymer (CH2CHCONH2) can be used to produce a uniform suspension of Y‐90 microspheres which lasts for several days. Additionally, a 0.4mm inner‐ diameter capillary tube was also filled with Y‐90 and placed in the Jaszczak phantom, with no modification, to provide a quantitative resolution evaluation . Results: The modified Jaszczak phantom was scanned on a prototype Siemens molecular CT through a research agreement with Siemens medical. Results gave a good indication of the accuracy in quantitation expected as well as image quality improvement over post‐ infusion bremsstrahlung SPECT that we may see when we begin Y‐90 post‐ infusion PET/CT patient imaging. Conclusion: The proposed modifications to the Jaszczak phantom allow for accurate, portable evaluation of a PET/CT system for quantitative Y‐90 imaging.

Impact of using scatter-mimicking beams instead of standard beams to measure penetration when assessing the protective value of radiation-protective garments

PURPOSEnUse standardized methods to determine how assessment of protective value of radiation-protective garments changes under conditions employing standard beam qualities, scatter-mimicking primary beams, and a modified Hp (10) measurement.nnnMETHODSnThe shielding properties of radiation-protective garments depend on the spectrum of beam energies striking the garment and the attenuation properties of materials used to construct the garment, including x-ray fluorescence produced by these materials. In this study the primary beam spectra employed during clinical interventional radiology and cardiology procedures (clinical primary beams, CPB) were identified using radiation dose structured reports (RDSR) and fluoroscope log data. Monte Carlo simulation was used to determine the scattered radiation spectra produced by these CPB during typical clinical application. For these scattered spectra, scatter-mimicking primary beams (SMPB) were determined using numerical optimization-based spectral reconstruction that adjusted kV and filtration to produce the SMPB that optimally matched the scattered spectrum for each CPB. The penetration of a subset of SMPB through four radiation-protective garments of varying compositions and nominal thicknesses was measured using a geometry specified by the International Electrotechnical Commission (IEC). The diagnostic radiological index of protection (DRIP), which increases with increasing penetration through a garment, was calculated using these measurements. Penetration through the same garments was measured for standard beams specified by the American Society of Testing and Materials (ASTM). Finally, 10xa0mm of PMMA was affixed to the inside of each garment and the DRIP remeasured in this configuration to simulate Hp (10).nnnRESULTSnThe SMPB based on actual CPB were in general characterized by lower kV (range 60-76) and higher half-value layer (HVL, range 3.44-4.89xa0mm Al) than standard beam qualities specified by ASTM (kV range 70-85; HVL range 3.4-4.0xa0mm Al). A lead garment of nominal thickness 0.5xa0mm (D) had a DRIP of 0.8%, two lead-free garments of 0.5xa0mm nominal thickness had DRIPs of 1.2% (A) and 2.2% (B), and a lead-free bilayer (C) had a DRIP of 1.4%. When standard beam qualities specified by the ASTM were used, the DRIP for D was 2.2%, 175% higher than the DRIP measured using SMPB, and for A, B, and C was 2.8%, 3.2%, and 2.9%, respectively. This was 133%, 45%, and 107% higher than the DRIP measured using SMPB. Differences between the DRIP of lead-alternative garments and the lead garment were reduced when measured with 10xa0mm of PMMA. Using this method, the measured DRIPs were 2.2% (A), 3.1% (B), 2.5% (C), and 2.3% (D).nnnCONCLUSIONSnPenetration of radiation through radiation-protective garments depended strongly on the methods and X-ray spectra used for evaluation. The DRIP was higher (i.e., protective value was lower) for lead-alternative garments than for lead garments in this evaluation. The DRIP was lower for all garments when SMPB based on actual clinical beam quality data were used to measure penetration compared to ASTM standard beams. Differences in penetration between lead-alternative and lead garments were less when the DRIP was measured with 10xa0mm of PMMA between the garment and the chamber.

Safety and efficacy of combined micropuncture and shallow angle femoral artery access for neurovascular angiography.

Introduction The AXERA 2 low-angle vascular access device utilizes a dual arteriotomy mechanism in which the standard access tract is compressed by a vascular sheath inserted over the second, low-angle tract. It is unknown whether this device could be effectively used with 21-gauge micropuncture access, as the micropuncture introducer makes a larger arteriotomy than the 19-gauge needle provided with the AXERA 2 system. Materials and Methods A retrospective review was performed on 189 patients who underwent common femoral artery access for diagnostic cerebrovascular angiography using either combined micropuncture and AXERA 2 access or standard access with manual pressure hemostasis. Demographic and procedural data were reviewed along with complications related to vascular access and times to bed elevation, ambulation and discharge. Results Combined micropuncture and AXERA 2 access was performed on 110 patients and 79 patients had standard access. The AXERA device was successfully used in 91.8% of the cases. Demographic data, anticoagulant use and sheath sizes were similar between both subsets. Use of the AXERA 2 was associated with two bleeding complications (1.8%) compared with 10 (12.7%) with manual pressure hemostasis alone. Institution-specific protocol allowed shorter mean manual compression time, as well as shorter times to ambulation and discharge with the AXERA 2. Conclusions Use of the AXERA 2 device with micropuncture access did not infer increased bleeding risk than standard arterial access in this patient series. The considerable incidence of device use failures suggests a learning curve associated with its use.

SU-D-209-05: Sensitivity of the Diagnostic Radiological Index of Protection (DRIP) to Procedural Factors in Fluoroscopy

PURPOSEnTo evaluate the sensitivity of the Diagnostic Radiological Index of Protection (DRIP) to procedural factors in fluoroscopy in an effort to determine an appropriate set of scatter-mimicking primary beams (SMPB) to be used in measuring the DRIP.nnnMETHODSnA series of clinical and factorial Monte Carlo simulations were conducted to determine the shape of the scattered X-ray spectra incident on the operator in different clinical fluoroscopy scenarios. Two clinical evaluations studied the sensitivity of the scattered spectrum to gantry angle and patient size while technical factors were varied according to measured automatic dose rate control (ADRC) data. Factorial evaluations studied the sensitivity of the scattered spectrum to gantry angle, field of view, patient size and beam quality for constant technical factors. Average energy was the figure of merit used to condense fluence in each energy bin to a single numerical index.nnnRESULTSnBeam quality had the strongest influence on the scattered spectrum in fluoroscopy. Many procedural factors affected the scattered spectrum indirectly through their effects on primary beam quality through ADRC, e.g., gantry angle and patient size. Lateral C-arm rotation, common in interventional cardiology, increased the energy of the scattered spectrum, regardless of the direction of rotation. The effect of patient size on scattered radiation depended on ADRC characteristics, patient size, and procedure type.nnnCONCLUSIONnThe scattered spectrum striking the operator in fluoroscopy, and therefore the DRIP, is most strongly influenced by primary beam quality, particularly kV. Use cases for protective garments should be classified by typical procedural primary beam qualities, which are governed by the ADRC according to the impacts of patient size, anatomical location, and gantry angle. These results will help determine an appropriate set of SMPB to be used for measuring the DRIP.