Daniel Siragusa

Selective angiographic embolization of blunt splenic traumatic injuries in adults decreases failure rate of nonoperative management.

BACKGROUND: To determine whether angioembolization (AE) in hemodynamically stable adult patients with blunt splenic trauma (BST) at high risk for failure of nonoperative management (NOM) (contrast blush [CB] on computed tomography, high-grade IV–V injuries, or decreasing hemoglobin) results in lower failure rates than reported. METHODS: The records of patients with BST from July 2000 to December 2010 at a Level I trauma center were retrospectively reviewed using National Trauma Registry of the American College of Surgeons. Failure of NOM (FNOM) occurred if splenic surgery was required after attempted NOM. Logistic regression analysis was used to identify factors associated with FNOM. RESULTS: A total of 1,039 patients with BST were found. Pediatric patients (age <17 years), those who died in the emergency department, and those requiring immediate surgery for hemodynamic instability were excluded. Of the 539 (64% of all BST) hemodynamically stable patients who underwent NOM, 104 (19%) underwent AE and 435 (81%) were observed without AE (NO-AE). FNOM for the various groups were as follows: overall NOM (4%), NO-AE (4%), and AE (4%). There was no significant difference in FNOM for NO-AE versus AE for grades I to III: grade I (1% vs. 0%, p = 1), grade II (2% vs. 0%, p = 0.318), and grade III (5% vs. 0%, p = 0.562); however, a significant decrease in FNOM was noted with the addition of AE for grades IV to V: grade IV (23% vs. 3%, p = 0.04) and grade V (63% vs. 9%, p = 0.03). Statistically significant independent risk factors for FNOM were grade IV to V injuries and CB. CONCLUSION: Application of strictly defined selection criteria for NOM and AE in patients with BST resulted in one of the lowest overall FNOM rates (4%). Hemodynamically stable BST patients are candidates for NOM with selective AE for high-risk patients with grade IV to V injuries, CB on initial computed tomography, and/or decreasing hemoglobin levels. LEVEL OF EVIDENCE: III, therapeutic study.

Skin dose mapping for fluoroscopically guided interventions

PURPOSE To introduce a new skin dose mapping software system for interventional fluoroscopy dose assessment and to analyze the benefits and limitations of patient-phantom matching. METHODS In this study, a new software system was developed for visualizing patient skin dose during interventional fluoroscopy procedures. The system works by translating the reference point air kerma to the location of the patients skin, which is represented by a computational model. In order to orient the model with the x-ray source, geometric parameters found within the radiation dose structured report (RDSR) are used along with a limited number of in-clinic measurements. The output of the system is a visual indication of skin dose mapped onto an anthropomorphic model at a resolution of 5 mm. In order to determine if patient-dependent and patient-sculpted models increase accuracy, peak skin dose was calculated for each of 26 patient-specific models and compared with doses calculated using an elliptical stylized model, a reference hybrid model, a matched patient-dependent model and one patient-sculpted model. Results were analyzed in terms of a percent difference using the doses calculated using the patient-specific model as the true standard. RESULTS Anthropometric matching, including the use of both patient-dependent and patient-sculpted phantoms, was shown most beneficial for left lateral and anterior-posterior projections. In these cases, the percent difference using a reference model was between 8 and 20%, using a patient-dependent model between 7 and 15%, and using a patient-sculpted model between 3 and 7%. Under the table tube configurations produced errors less than 5% in most situations due to the flattening affects of the table and pad, and the fact that table height is the main determination of source-to-skin distance for these configurations. In addition to these results, several skin dose maps were produced and a prototype display system was placed on the in-clinic monitor of an interventional fluoroscopy system. CONCLUSIONS The skin dose mapping program developed in this work represents a new tool that, as the RDSR becomes available through automated export or real-time streaming, can provide the interventional physician information needed to modify behavior when clinically appropriate. The program is nonproprietary and transferable, and also functions independent to the software systems already installed on the control room workstation. The next step will be clinical implementation where the workflow will be optimized along with further analysis of real-time capabilities.

At first blush: absence of computed tomography contrast extravasation in Grade IV or V adult blunt splenic trauma should not preclude angioembolization.

BACKGROUND To clarify the role, indications, and outcomes for angioembolization (AE) of nonoperatively managed (NOM) splenic trauma, the implications of absent contrast blush (CB) on computed tomography of high-grade (IV–V) blunt splenic trauma (BST) in adults were analyzed. METHODS All BST patients presenting at a single institution from July 2000 to December 2011 were retrospectively reviewed. Grade of injury (American Association for the Surgery of Trauma scale), CB on initial computed tomography, numbers of NOM and undergoing AE, and failures of NOM were analyzed. Statistical analysis was performed using &khgr;2. RESULTS Of the 1,056 total BST patients, 556 (64%) were hemodynamically stable and eligible for NOM; 95 NOM patients (17%) had CB. AE was performed in 88 of these, with angiographic extravasation found in 86 (97.7%), and 3 of these 88 (3.4%) failed NOM. The remaining 7 CBs were observed without AE, of which 5 (71.4%) failed NOM (p = 0.0004). Of all 556 NOM patients, 51 (9.5%) had high-grade injuries without CB; 20 of these (39%) underwent AE, 17 (85.0%) underwent angiographic extravasation, and there were no NOM failures in this group. The other 31 high-grade injuries without CB or AE had 8 failures of NOM (26%) (p = 0.03). CONCLUSION The strong correlation of CB with active bleeding on angiogram mandates AE for CB in all BST undergoing NOM. However, the absence of CB in high-grade (IV–V) BST does not reliably exclude active bleeding. This may be the reason for the high reported failure rates of NOM in high-grade (IV–V) BST because AE is not typically performed in the absence of CB. These data suggest that all hemodynamically stable high-grade (IV–V) BST in adults should undergo AE regardless of CB to optimize the success and safety of NOM. LEVEL OF EVIDENCE Therapeutic study, level III.

The influence of patient size on dose conversion coefficients: a hybrid phantom study for adult cardiac catheterization.

In this study, the influence of patient size on organ and effective dose conversion coefficients (DCCs) was investigated for a representative interventional fluoroscopic procedure-cardiac catheterization. The study was performed using hybrid phantoms representing an underweight, average and overweight American adult male. Reference body sizes were determined using the NHANES III database and parameterized based on standing height and total body mass. Organ and effective dose conversion coefficients were calculated for anterior-posterior, posterior-anterior, left anterior oblique and right anterior oblique projections using the Monte Carlo code MCNPX 2.5.0 with the metric dose area product being used as the normalization factor. Results show body size to have a clear influence on DCCs which increased noticeably when body size decreased. It was also shown that if patient size is neglected when choosing a DCC, the organ and effective dose will be underestimated to an underweight patient and will be overestimated to an underweight patient, with errors as large as 113% for certain projections. Results were further compared with those published for a KTMAN-2 Korean patient-specific tomographic phantom. The published DCCs aligned best with the hybrid phantom which most closely matched in overall body size. These results highlighted the need for and the advantages of phantom-patient matching, and it is recommended that hybrid phantoms be used to create a more diverse library of patient-dependent anthropomorphic phantoms for medical dose reconstruction.

Age Does Not Affect Outcomes of Nonoperative Management of Blunt Splenic Trauma

BACKGROUND The purpose of this study was to examine the effect of age on the outcomes of nonoperative management (NOM) of blunt splenic trauma (BST). STUDY DESIGN The records of patients with BST, from July 2000 to December 2010 at a level I trauma center, were retrospectively reviewed using NTRACS (National Trauma Registry of the American College of Surgeons). Patients were divided into 2 age groups: 17 to 55 years and greater than 55 years. Stepwise logistic regression analysis was used to identify risk factors associated with failure of nonoperative management (FNOM). RESULTS There were 539 hemodynamically stable patients with BST who underwent NOM. Of these, 459 were age 55 or less, and 80 were greater than 55. Overall, there was no significant difference in FNOM rate for patients age 55 or less vs greater than 55 (4% vs 5%, p = 0.73). This also held true when FNOM was analyzed by each grade: I (1% vs 3%, p = 0.38), II (2% vs 0%, p = 1.0), III (4% vs 0%, p = 1.0), IV (8% vs 20%, p = 0.33), and V (21% vs 50%, p = 0.47). The addition of angioembolization (AE) to high grade IV to V injuries significantly lowered the FNOM rate: age 55 or less (6% AE vs 28% NO-AE, p = 0.02); with a trend toward significance for age greater than 55 (0% AE vs 60% NO-AE, p = 0.2). Age was not a statistically significant independent risk factor for FNOM (p = 0.37). CONCLUSIONS Age does not affect outcomes of NOM of BST. High grade (IV to V) injuries are not a contraindication to NOM for patients older than 55. As experience with AE grows in patients with high grade injury and age greater than 55, it may prove to be a valuable adjunct to NOM in this group of patients.

Requirements for Training in Interventional Radiology

PREAMBLE In recent years, the Society of Interventional Radiology (SIR) has become aware of a growing heterogeneity in the learning experiences of radiology trainees (residents and fellows) as it pertains to the subject of interventional radiology (IR). Unfortunately, the Accreditation Council for Graduate Medical Education (ACGME) program requirements are somewhat vague as to what constitutes adequate training in this field. Therefore, a task force was created to create guidelines for training in the field of IR. Task force members included physicians who practice in academic and private-practice settings. Also, the task force contained a cross-section of thought leaders in the various clinical realms of IR (peripheral arterial disease, interventional oncology, venous disease, interventional neuroradiology, and renal insufficiency). Many members are current or past program directors of diagnostic radiology (DR) residencies or IR fellowships. The guidelines put forth in this document are intended for the training of radiology residents and IR fellows in the knowledge base and technical skills related to minimally invasive interventional procedures. As part of this education, trainees must gain an appropriate depth of understanding of the disease states being treated and their clinical management to allow for optimal clinical outcomes. It is intended that program directors in DR residencies and program directors in vascular and IR (VIR) fellowships will use this document as a basis for the creation of program-specific curricula and goals and objectives documents for trainees. In addition, this document is intended for reference by radiology chairs, designated institutional officials, and deans so they may allocate appropriate resources to training programs to meet these training requirements. Finally, although training paradigms differ around the world, it is hoped that these guidelines will also be helpful in the creation of educational curricula for international IR programs as well. SIR recognizes that the multiple levels of trainees covered by this document will require differing experiences to meet their differing needs. For example, the DR trainee who is pursuing a career in a general radiology or in a diagnostic imaging subspecialty will not require the same training as a resident planning to enter into a VIR fellowship. Therefore, four separate sets of training requirements will be set forth in this document:

To nearly come full circle: Nonoperative management of high-grade IV–V blunt splenic trauma is safe using a protocol with routine angioembolization

Introduction Nonoperative management (NOM) of hemodynamically stable high-grade (IV–V) blunt splenic trauma remains controversial given the high failure rates (19%) that persist despite angioembolization (AE) protocols. The NOM protocol was modified in 2011 to include mandatory AE of all grade (IV–V) injuries without contrast blush (CB) along with selective AE of grade (I–V) with CB. The purpose of this study was to determine if this new AE (NAE) protocol significantly lowered the failure rates for grade (IV–V) injuries allowing for safe observation without surgery and if the exclusion of grade III injuries allowed for the prevention of unnecessary angiograms without affecting the overall failure rates. Methods The records of patients with blunt splenic trauma from January 2000 to October 2014 at a Level I trauma center were retrospectively reviewed. Patients were divided into two groups and failure of NOM (FNOM) rates compared: NAE protocol (2011–2014) with mandatory AE for all grade (IV–V) injuries without CB and selective AE for grade (I–V) with CB versus old AE (OAE) protocol (2000–2010) with selective AE for grade (I–V) with CB. Results Seven hundred twelve patients underwent NOM with 522 (73%) in the OAE group and 190 (27%) in the NAE group. Evolving from the OAE to the NAE strategy resulted in a significantly lower FNOM rate for the overall group (grade I–V) (OAE vs. NAE, 4% to 1%, p = 0.04) and the grade (IV–V) group (OAE vs. NAE, 19% vs. 3%, p = 0.01). Angiograms were avoided in 113 grade (I–III) injuries with no CB; these patients had NOM with observation alone and none failed. Conclusions A protocol using mandatory AE of all high-grade (IV–V) injuries without CB and selective AE of grade (I–V) with CB may provide for optimum salvage with safe NOM of the high-grade injuries (IV–V) and limited unnecessary angiograms. LEVEL OF EVIDENCE Therapeutic study, level IV.

A hybrid phantom system for patient skin and organ dosimetry in fluoroscopically guided interventions

Purpose The purpose of this study was to investigate calibrations for improved estimates of skin dose and to develop software for computing absorbed organ doses for fluoroscopically guided interventions (FGIs) with the use of radiation dose structured reports (RDSR) and the UF/NCI family of hybrid computational phantoms. Methods and materials Institutional review board approval was obtained for this retrospective study in which ten RDSRs were selected for their high cumulative reference air kerma values. Skin doses were computed using the University of Floridas rapid in‐clinic peak skin dose algorithm (or UF‐RIPSA). Kerma‐area product (KAP) meter calibrations and attenuation of the tabletop with pad were incorporated into the UF‐RIPSA. To compute absorbed organ doses the RDSRs were coupled with software to develop Monte Carlo input decks for each irradiation event. The effects of spectrum matching were explored by modeling (a) a polychromatic x‐ray energy beam made to match measured first half‐value layers of aluminum, (b) an unmatched spectrum, (c) and a mono‐energetic beam equivalent to the effective x‐ray energy. The authors also considered the practicality of computing organ doses for each irradiation event within a RDSR. Results The KAP meter is highly dependent on the quality of the x‐ray spectra. Monte Carlo based attenuation coefficients for configurations in which the beam is transmitted through the tabletop with pad reduced the amount by which the software overestimated skin doses. For absorbed organ dose computations, the average ratios of computed organ doses for a non‐fitted to fitted spectrum and effective energy to fitted spectrum were 0.45 and 0.03, respectively. Monte Carlo simulations on average took 38 min per patient. All in‐field organ tallies converged with a relative error of less than 1% and out‐of‐field organs tallies within 10% relative error. Conclusions This work details changes to the UF‐RIPSA software that include an expanded library of computational phantoms, attenuation coefficients for tabletop with pad, and calibration curves for the KAP meter. For the computation of absorbed organ dose, it is possible to model each irradiation event separately on a patient‐dependent model that best morphometrically matches the patient, thus providing a full report of internal organ doses for FGI patients.

Imaging-guided percutaneous biopsy of hepatic masses.

Imaging-guided biopsy of hepatic masses has become the standard for diagnosis. This article reviews the computed tomography, ultrasound, and magnetic resonance imaging characteristics of the more common benign and malignant hepatic masses. This is followed by a description of the procedure from preprocedure work-up to postprocedure care, with a discussion of indications, contraindications, complications, and technique.

Physical validation of UF‐RIPSA: A rapid in‐clinic peak skin dose mapping algorithm for fluoroscopically guided interventions

Abstract Purpose The purpose of this study was to experimentally validate UF‐RIPSA, a rapid in‐clinic peak skin dose mapping algorithm developed at the University of Florida using optically stimulated luminescent dosimeters (OSLDs) and tissue‐equivalent phantoms. Methods The OSLDs used in this study were InLightTM Nanodot dosimeters by Landauer, Inc. The OSLDs were exposed to nine different beam qualities while either free‐in‐air or on the surface of a tissue equivalent phantom. The irradiation of the OSLDs was then modeled using Monte Carlo techniques to derive correction factors between free‐in‐air exposures and more complex irradiation geometries. A grid of OSLDs on the surface of a tissue equivalent phantom was irradiated with two fluoroscopic x ray fields generated by the Siemens Artis zee bi‐plane fluoroscopic unit. The location of each OSLD within the grid was noted and its dose reading compared with UF‐RIPSA results. Results With the use of Monte Carlo correction factors, the OSLDs response under complex irradiation geometries can be predicted from its free‐in‐air response. The predicted values had a percent error of −8.7% to +3.2% with a predicted value that was on average 5% below the measured value. Agreement within 9% was observed between the values of the OSLDs and RIPSA when irradiated directly on the phantom and within 14% when the beam first traverses the tabletop and pad. Conclusions The UF‐RIPSA only computes dose values to areas of irradiated skin determined to be directly within the x ray field since the algorithm is based upon ray tracing of the reported reference air kerma value, with subsequent corrections for air‐to‐tissue dose conversion, x ray backscatter, and table/pad attenuation. The UF‐RIPSA algorithm thus does not include the dose contribution of scatter radiation from adjacent fields. Despite this limitation, UF‐RIPSA is shown to be fairly robust when computing skin dose to patients undergoing fluoroscopically guided interventions.