Roger Y. Shifrin

The UF family of hybrid phantoms of the developing human fetus for computational radiation dosimetry

Historically, the development of computational phantoms for radiation dosimetry has primarily been directed at capturing and representing adult and pediatric anatomy, with less emphasis devoted to models of the human fetus. As concern grows over possible radiation-induced cancers from medical and non-medical exposures of the pregnant female, the need to better quantify fetal radiation doses, particularly at the organ-level, also increases. Studies such as the European Unions SOLO (Epidemiological Studies of Exposed Southern Urals Populations) hope to improve our understanding of cancer risks following chronic in utero radiation exposure. For projects such as SOLO, currently available fetal anatomic models do not provide sufficient anatomical detail for organ-level dose assessment. To address this need, two fetal hybrid computational phantoms were constructed using high-quality magnetic resonance imaging and computed tomography image sets obtained for two well-preserved fetal specimens aged 11.5 and 21 weeks post-conception. Individual soft tissue organs, bone sites and outer body contours were segmented from these images using 3D-DOCTOR™ and then imported to the 3D modeling software package Rhinoceros™ for further modeling and conversion of soft tissue organs, certain bone sites and outer body contours to deformable non-uniform rational B-spline surfaces. The two specimen-specific phantoms, along with a modified version of the 38 week UF hybrid newborn phantom, comprised a set of base phantoms from which a series of hybrid computational phantoms was derived for fetal ages 8, 10, 15, 20, 25, 30, 35 and 38 weeks post-conception. The methodology used to construct the series of phantoms accounted for the following age-dependent parameters: (1) variations in skeletal size and proportion, (2) bone-dependent variations in relative levels of bone growth, (3) variations in individual organ masses and total fetal masses and (4) statistical percentile variations in skeletal size, individual organ masses and total fetal masses. The resulting series of fetal hybrid computational phantoms is applicable to organ-level and bone-level internal and external radiation dosimetry for human fetuses of various ages and weight percentiles.

Responsible Use of Computed Tomography in the Evaluation of Coronary Artery Disease and Chest Pain

Many options are available to clinicians for the noninvasive evaluation of the cardiovascular system and patient concerns about chest discomfort. Cardiac computed tomography (CT) is a rapidly advancing field of noninvasive imaging. Computed tomography incorporates coronary artery calcium scoring, coronary angiography, ventricular functional analysis, and information about noncardiac thoracic anatomy. We searched the PubMed database and Google from inception to September 2009 for resources on the accuracy, risk, and predictive capacity of coronary artery calcium scoring and CT coronary angiography and have reviewed them herein. Cardiac CT provides diagnostic information comparable to echocardiography, nuclear myocardial perfusion imaging, positron emission tomography, and magnetic resonance imaging. A cardiac CT study can be completed in minutes. In patients with a nondiagnostic stress test result, cardiac CT can preclude the need for invasive angiography. Prognostic information portends excellent outcomes in patients with normal study results. Use of cardiac CT can reduce health care costs and length of emergency department stays for patients with chest pain. Cardiac CT examination provides clinically relevant information at a radiation dose similar to well-established technologies, such as nuclear myocardial perfusion imaging. Advances in technique can reduce radiation dose by 90%. With appropriate patient selection, cardiac CT can accurately diagnose heart disease, markedly decrease health care costs, and reliably predict clinical outcomes.

The UF Family of hybrid phantoms of the pregnant female for computational radiation dosimetry

Efforts to assess in utero radiation doses and related quantities to the developing fetus should account for the presence of the surrounding maternal tissues. Maternal tissues can provide varying levels of protection to the fetus by shielding externally-emitted radiation or, alternatively, can become sources of internally-emitted radiation following the biokinetic uptake of medically-administered radiopharmaceuticals or radionuclides located in the surrounding environment--as in the case of the European Unions SOLO project (Epidemiological Studies of Exposed Southern Urals Populations). The University of Florida had previously addressed limitations in available computational phantom representation of the developing fetus by constructing a series of hybrid computational fetal phantoms at eight different ages and three weight percentiles. Using CT image sets of pregnant patients contoured using 3D-DOCTOR(TM), the eight 50th percentile fetal phantoms from that study were systematically combined in Rhinoceros(TM) with the UF adult non-pregnant female to yield a series of reference pregnant female phantoms at fetal ages 8, 10, 15, 20, 25, 30, 35 and 38 weeks post-conception. Deformable, non-uniform rational B-spline surfaces were utilized to alter contoured maternal anatomy in order to (1) accurately position and orient each fetus and surrounding maternal tissues and (2) match target masses of maternal soft tissue organs to reference data reported in the literature.

Design and implementation of a stand-alone chest pain evaluation center within an academic emergency department.

Chest pain is a common presenting symptom for emergency department (ED) patients; however, a thorough cardiac evaluation can be difficult to complete within the ED setting. Implementation of a stand-alone unit for the evaluation of chest pain may improve care for patients with chest pain. We designed a protocol for identifying patients without an acute coronary syndrome and with low-to-intermediate likelihood of obstructive coronary artery disease (CAD). These patients were monitored in a stand-alone chest pain evaluation center (CPEC) staffed with a small group of providers and tested for CAD, if necessary. In the first 6 weeks of operation, 181 patients were evaluated in the CPEC. The prevalence of CAD risk factors was low. Of the 181 patients, 159 (88%) were discharged home and 22 (12%) required admission to the hospital for further care. We compared the number of chest pain evaluations and admissions for first 6 weeks of operation to the same 6-week period from the 2 previous years. Whereas ED chest pain evaluations increased 66% over the 2-year time frame, the proportion admitted to the hospital decreased from 53% to 42% (P < 0.0001). In conclusion, evidence-based evaluation of chest pain in patients without acute coronary syndrome and with low-to-intermediate likelihood of obstructive CAD can result in the significant majority of patients being discharged from the ED. Creation of a stand-alone CPEC in an academic hospital was associated with a significant reduction in hospital admissions.

Rapid liver enlargement and hepatic failure secondary to radiographic occult tumor invasion: two case reports and review of the literature

IntroductionUnfamiliarity with certain clinical presentations, as illustrated in these cases, can lead to delayed diagnoses that in turn cause increased morbidity, prolonged hospitalization, and the need for autopsy.Case presentationIn Case 1, a 63-year-old Caucasian woman presented with hepatic enlargement and insufficiency which progressed and resulted in her death over a period of less than 2 weeks. The patient underwent a detailed workup included magnetic resonance imaging and computed tomography scan of her liver, which did not reveal the source of her liver enlargement. Due to her progressive liver enlargement and insufficiency, she developed a life-threatening esophageal variceal bleeding during her hospital stay which further delayed the attainment of her diagnosis. She finally underwent a videoscopic laparotomy and liver biopsy which revealed complete replacement and filling in of the liver sinuous with Indian filing lobular breast cancer. The patient died shortly after her diagnosis and before she could be discharged.In Case 2, a 68-year-old Caucasian woman with non-small-cell lung cancer was admitted to our Oncology in-patient service with a presentation of rapid hepatic insufficiency and severe liver enlargement. Like the patient in Case 1, during her hospitalization, this patient underwent a thorough radiographic evaluation, including computed tomography and magnetic resonance imaging, to identify the source of her symptoms. Radiographic imaging showed only hepatomegaly and no discrete focal lesions. As the multiple imaging studies over a period of a week did not reveal a clear cause for her symptoms, she finally underwent an interventional radiology core biopsy which showed complete replacement of her liver with non-small-cell lung cancer. Her condition rapidly progressed due to continued liver enlargement and she died due to frank liver failure before her diagnosis was affirmed and she could be discharged.ConclusionBoth of these cases illustrate the potential difficulties in diagnosing liver-infiltrative malignancy and the need for a high index of clinical suspicion for occult infiltrative malignancy in the liver to determine the appropriate therapeutic intervention, including further treatment of malignancy, palliative care, or determination of candidacy for liver transplantation. Because the diagnosis for the cause of symptoms and hepatomegaly was elucidated only by liver biopsy which occurred much later in their hospital course, both patients died while in the hospital instead of at home or in a hospice. Moreover, these delays in diagnosis and development of morbidities due to the progressing liver failure further prevent any possibility of early initiation of palliative treatment. Initial recognition of this type of presentation can lead to a prompt diagnostic biopsy and diagnosis. Giving the patient a correct diagnosis is one of the fundamental goals of oncology: a goal that, as illustrated in literature review, is not always achieved. Although treatment options in such cases often may be limited, prompt discharge from the hospital and/or admission into a hospice program can potentially afford the patient the best quality of life and help protect the patient’s dignity.

Retained products of conception through a perforated uterine wall following elective abortion: a unique case report.

A 14-year-old G1P0010 elected to terminate an undesired pregnancy at approximately 17 weeks gestation at a mobile clinic. Five weeks after termination, the patient experienced two heavy menses associated with significant pelvic pain necessitating an emergency room visit to an outside hospital. An ultrasound examination at the outside facility was obtained, and the patient was diagnosed with a calcified fibroid as the cause of pelvic pain. The patient then presented to our facility 8.5 weeks after termination with the chief complaint of ongoing pelvic pain. Medical records from the mobile clinic where the patient initially underwent an elective abortion were not available for review; therefore, details of the procedure were unknown. At our facility, the patient’s labs were notable for a normal quantitative β-hCG at 2 mlU/mL (normal, <3 mlU/mL) and elevated alpha fetoprotein at 60.4 ng/mL (normal, 0.0–8.7 ng/mL). The patient’s history of prior elective termination of pregnancy, extreme pelvic pain on physical examination, and persistently elevated alpha fetal protein were concerning for retained products of conception (POC). A repeat pelvic ultrasound at our institution revealed a 4-cm heterogeneous round mass with rim-like and linear calcifications suspicious for extrauterine retained POC (Fig. 1). An MRI was obtained to evaluate the integrity of the uterus. The MRI revealed distortion and sharp angulation of the endometrial canal (Fig. 2). The apex of the distorted canal centered at the anterior lower uterine segment leading to a 4-cm rounded mass external and anterior to the uterus (Fig. 3). These findings were consistent with a uterine perforation with extruded products of conception. The mass had tissue signal consistent with bone and soft tissue, with associated cystic material. The patient underwent laparoscopy for removal of the mass and uterine perforation repair. At the time of laparoscopy, a large featureless, grayish mass was noted in the anterior cul-de-sac, with inflammatory fibrinous reactive tissue, free serous fluid, and significant bowel adhesions. The mass was adherent to a 4-cm anterior uterine defect in the lower uterine segment (Fig. 4). Pathologic examination of the mass revealed partially necrotic tissue with fragments of bone and immature cartilage consistent with retained POC, particularly a retained fetal head. The patient recovered from the surgery without complications and was counseled on pregnancy prevention.

SU‐E‐I‐50: The UF Family of Hybrid Phantoms of the Developing Human Fetus for Computational Radiation Dosimetry

Purpose: Historically, the development of computational phantoms for radiationdosimetry have primarily been directed at capturing and representing adult and pediatric anatomy, with less emphasis devoted to models of the human fetus. As concern grows over possible radiation‐ induced cancers from medical and non‐medical exposures of the pregnant female, the need to better quantify fetal radiation doses, particularly at the organ‐level, also increases. To address this need a series of hybrid computational phantoms was constructed for fetal ages 8, 10, 15, 20, 25, 30, 35 and 38 weeks post‐conception. Methods: Two specimen‐specific fetal hybrid computational phantoms were constructed using high‐quality magnetic resonance imaging(MRI) and computed tomography(CT)image sets obtained for two well‐preserved fetal specimens aged 11.5 and 21 weeks post‐conception. Individual soft tissueorgans, bone sites, and outer body contours were segmented from the images using 3D‐DOCTORTM and imported into the 3D modeling software package RhinocerosTM for further modeling and conversion of soft tissueorgans, certain bone sites and outer body contours to deformable non‐uniform rational B‐spline (NURBS) surfaces. The two specimen‐specific phantoms, along with a modified version of the 38 week UF hybrid newborn phantom, comprised a set of base phantoms from which a series of hybrid computational phantoms was derived for fetal ages 8, 10, 15, 20, 25, 30, 35 and 38 weeks post‐ conception. Results: A set of fetal computational phantoms accounting for the following age‐dependent parameters: (1) variations in skeletal size and proportion, (2) bone‐dependent variations in relative levels of bone growth, (3) variations in individual organ masses and total fetal masses and (4) statistical percentile variations in skeletal size, individual organ masses, and total fetal masses. Conclusions: The resulting series of fetal hybrid computational phantoms is capable of organ‐level and bone‐level internal and external radiationdosimetry for human fetuses of various ages and weight percentiles.

Aorto-Pulmonary Window in an Adult: Utility of Multimodality Imaging

From the *Department of Pediatrics, University of Florida, Gainesville, Florida; †Department of Radiology, University of Florida, Gainesville, Florida; ‡Department of Cardiology, University of Florida, Gainesville, Florida; and the Congenital Heart Center, University of Florida, Gainesville, Florida. Manuscript received November 8, 2010; accepted November 19, 2010. A46-year-old man with a history of cardiothoracic surgery at 20 years of age of uncertain type sought treatment for worsening dyspnea on exertion and episodes of dizziness. He had central cyanosis, clubbing, and baseline saturations of 96% that dropped to 86% with exercise. Initial transthoracic echocardiogram (A, Online Video 1) showed moderate right ventricular hypertrophy with dysfunction and right ventricular hypertension. It was also indicative of a residual bidirectional aortopulmonary shunt at the level of the prior surgically placed patch (B, Online Video 2). Cardiac magnetic resonance imaging confirmed the presence of the right ventricular hypertrophy and associated dysfunction (C, Online Video 3) with late gadolinium enhancement (D, Online Video 4) and the small bidirectional aortopulmonary shunt (E, Online Video 5). This multimodality imaging contributed to the subsequent Published by Elsevier Inc. doi:10.1016/j.jacc.2010.11.076

SU‐GG‐I‐51: Hybrid Computational Phantoms of the Developing Human Fetus

Purpose: Anthropomorphic computational phantoms are a useful tool for assessing ionizing radiationdosesdelivered through medical imaging,radiation therapy, and nuclear medicine procedures. The majority of computational phantom construction efforts have been directed towards pediatric and adult populations, with comparatively little treatment given to the developing fetus. Fetal radiosensitivity combined with growing concerns regarding medical radiationdoses suggests a need for computational phantoms that provide adequate representation of fetal anatomy. This work introduces a new set of fetal computational phantoms to be used for use radiationdosimetry purposes. Method and Materials: High‐resolution MR and CTimages of two preserved fetal specimens (13.5 and 23 weeks) were utilized to construct computational phantoms of the developing fetus. 4.7 T MR images of the younger fetus and clinical 1.5 T MR and CTimages of the older fetus were acquired. Images were segmented using 3D‐Doctor™ and exported to Rhinoceros™ where non‐uniform rational B‐spline (NURBS) surfaces were used to offset minor imaging and segmentation artifacts in the skeleton. Published fetal biometry data were used for age verification and as design criteria for volumetrically adjusting the phantoms to different gestational ages. Results: The thorough representation of the internal fetal anatomy comprising these phantoms is on par with currently available pediatric and adult computational phantoms. Conclusion: High‐resolution MR and CTimages of two preserved fetuses, in conjunction with established segmentation and modeling techniques, have produced two computational phantoms that provide improved representation of the fetal internal anatomy compared to those currently available. In the future, completed fetal phantoms may be combined with an adult female phantom to provide a powerful tool with which to simulate in utero internal and external medical radiation exposures.