Qualitative Assessment of Diffusion Weighted Imaging and Susceptibility Weighted Imaging of Myeloid Sarcoma Involving the Brain.

BACKGROUND AND PURPOSE: Myeloid sarcoma is a rare form of extramedullary leukemia, which can present with or without systemic leukemia. The purpose of this study was to evaluate characteristic computed tomography (CT) and magnetic resonance imaging (MRI) findings (including diffusion weighted imaging and susceptibility weighted imaging) of myeloid sarcoma involving the brain. MATERIALS AND METHODS: One hundred nine patients with pathologically proven myeloid sarcoma underwent pretreatment CT and MRI, which were retrospectively reviewed. Computed tomography and MRI characteristics reviewed include lesion location, shape, size, architecture, margins, ± multiplicity, ± bone destruction, pattern and degree of enhancement, ± restricted diffusion, and ± susceptibility artifact. RESULTS: Twenty-five patients (14 men, 11 women; mean age, 55 years; range, 9-80 years) met the inclusion criteria. Acute myeloid leukemia with subtypes M3 (44.4%) and M5 (22.2%) were the most common. On unenhanced CT, mean lesion size was 1.9 ± 0.4 cm; 60% were intra-axial hyperdense masses, 8% were intraventricular hyperdense masses, 12% were isodense intra-axial masses, and 20% of cases were extra-axial hyperdense nodular masses. There was no observable intralesional or perilesional calcium. On MRI, mean lesion size was 2.1 ± 0.6 cm. The lesions were isointense (80%) or hypointense (20%) on T1-weighted images with homogeneous (88%) or heterogeneous (12%) enhancement. On fluid-attenuated inversion recovery and T2-weighted images, lesions were hyperintense (96%) or isointense (4%) with mild vasogenic edema. Majority (96%) of cases demonstrated restricted diffusion, whereas only a few (16%) demonstrated susceptibility artifact. CONCLUSIONS: In patients with history of leukemia or myeloproliferative disorder, identification of homogenous mass hyperdense on unenhanced CT, T1 isointense, and T2/fluid-attenuated inversion recovery hyperintense with restricted diffusion and homogenous postcontrast enhancement without significant susceptibility artifact is suggestive of myeloid sarcoma.

Quantitative Evaluation of Noncontrast Computed Tomography of the Head for Assessment of Anemia.

BACKGROUND AND PURPOSE: Anemia is an underdiagnosed clinical entity with significant mortality and morbidity. We aimed to assess whether attenuation of dural venous sinuses correlates with hemoglobin/hematocrit and to determine if the degree of anemia can be predicted by quantitative analysis of unenhanced computed tomography (CT) of the head. MATERIALS AND METHODS: This is an institutional review board-approved retrospective study including 500 patients who underwent emergency department investigation for potential central nervous system etiology of their symptoms with unenhanced CT head at a tertiary care center. Computed tomographic attenuation values were obtained by 2 independent readers, whereas 2 separate investigators collected clinical data. Regression analyses were performed to evaluate the strength of correlation and the predictability of anemia and its severity on unenhanced CT. Receiver operating characteristic curve analyses were performed to evaluate sensitivity, specificity, as well as positive and negative predictive values. RESULTS: A total of 243 met the inclusion criteria, and attenuation values for all the dural venous sinuses were averaged and categorized according to hemoglobin values of less than 8, 8 to 10, 10 to 14, and greater than 14. Mean CT attenuation values for both readers were 36.30, 42.35, 47.99, and 53.25 Hounsfield units. Regression analysis revealed the highest positive correlation of hemoglobin/hematocrit with attenuation at the confluence of sinuses with R value of 0.63 and 0.60. The sensitivity, specificity, and negative predictive value of detecting hemoglobin of less than 10 at confluence of sinuses were 91.2%, 88.5%, and 98.6%, respectively. Interobserver agreement was found to be good (0.64) using the κ statistic. CONCLUSIONS: Our study substantiates direct positive correlation between CT attenuation of dural venous sinuses and hemoglobin/hematocrit, with strongest correlation at the confluence of sinuses with good sensitivity, specificity, and negative predictive value.

Reduction of fetal dose in computed tomography using anterior shields.

OBJECTIVE: The objective of this study was to assess the potential of anterior in beam bismuth shields placed on the abdomen and the pelvis of a RANDO phantom to decrease radiation dose to a simulated fetus. METHODS: Thermal luminescent dosimeters irradiated in a RANDO phantom were used to measure radiation dose at 0 weeks and 18 weeks after conception. An 18-week gestation was simulated by adding the corresponding equivalent of super-stuff to account for additional subcutaneous tissue. To assess image quality, a 461A body phantom with low contrast resolution phantom insert was used. The minimum size of low contrast resolution target visualize was recorded with no shielding and 25-cm-wide shielding. RESULTS: With shields, there was a radiation dose reduction of 19% to 23% at 0-week gestation and 16% to 24% at 18-week gestation. No qualitative difference was found in low contrast detectability with the shields. CONCLUSIONS: These shields reduce fetal radiation exposure early in pregnancy with acceptable image quality.

Fetal radiation dose during gestation estimated on an anthropomorphic phantom for three generations of CT scanners.

OBJECTIVE: The purpose of this study is to determine fetal dose during four different stages of pregnancy for both pulmonary CT angiogram and abdominal and pelvic CT examination on 4-, 16-, and 64-MDCT scanners measured in an anthropomorphic phantom simulating a pregnant patient. MATERIALS AND METHODS: Pulmonary angiograms and abdominal and pelvic studies were performed on a phantom on 4-, 16-, and 64-MDCT scanners. Fetal positioning and mean fetal depth were determined using data from ultrasound examinations of a large cohort of patients. Scans were performed for early pregnancy and for 10, 18, and 36 weeks. Gestational age, fetal dose, and entrance skin exposure were measured. RESULTS: When constant parameters were used for pulmonary CT angiograms, the fetal radiation dose was not significantly associated with gestational age. For abdominal examinations, the 64-MDCT scanner imparted a 20% higher dose during the third trimester than did the other scanners. When scanning parameters were kept constant between machines, gestational age and fetal dose were not significantly different. However, when the manufacturer-recommended protocols for pregnant patients were used, the dose was significantly higher in the third trimester on the 64-MDCT scanner. CONCLUSION: The 64-MDCT scanner is the most dose-efficient machine when the fetus is outside the direct scan volume, as in the case of pulmonary angiograms. For abdominal examinations, the 64-MDCT scanner imparted the highest fetal dose. This finding is attributable to the increased tube current used to penetrate the larger amount of soft tissue in late pregnancy. Abdominal shielding may reduce fetal dose without affecting diagnostic ability.

Globe trauma.

In the United States, it is estimated that 3% of all emergency room visits are the result of eye injury, with many seen in combination with other orbital injuries. These often result from motor vehicle accidents and sports-related injuries. Clinical ophthalmologic examination is the key to rapid and accurate diagnosis of most ocular injuries. Imaging, in combination with the ophthalmologic examination, can be a powerful tool in the evaluation of traumatic injury to the globe. We review the roles of computed tomography, magnetic resonance imaging, and ultrasound in the evaluation of these patients and illustrate common and uncommon traumatic ocular pathology.

A prospective, multicenter pilot study investigating the utility of flat detector derived parenchymal blood volume maps to estimate cerebral blood volume in stroke patients.

PURPOSE: Newer flat panel angiographic detector (FD) systems have the capability to generate parenchymal blood volume (PBV) maps. The ability to generate these maps in the angiographic suite has the potential to markedly expedite the triage and treatment of patients with acute ischemic stroke. The present study compares FP-PBV maps with cerebral blood volume (CBV) maps derived using standard dynamic CT perfusion (CTP) in a population of patients with stroke. METHODS: 56 patients with cerebrovascular ischemic disease at two participating institutions prospectively underwent both standard dynamic CTP imaging followed by FD-PBV imaging (syngo Neuro PBV IR; Siemens, Erlangen, Germany) under a protocol approved by both institutional review boards. The feasibility of the FD system to generate PBV maps was assessed. The radiation doses for both studies were compared. The sensitivity and specificity of the PBV technique to detect (1) any blood volume deficit and (2) a blood volume deficit greater than one-third of a vascular territory, were defined using standard dynamic CTP CBV maps as the gold standard. RESULTS: Of the 56 patients imaged, PBV maps were technically adequate in 42 (75%). The 14 inadequate studies were not interpretable secondary to patient motion/positioning (n=4), an injection issue (n=2), or another reason (n=8). The average dose for FD-PBV was 219 mGy (median 208) versus 204 mGy (median 201) for CT-CBV. On CT-CBV maps 26 of 42 had a CBV deficit (61.9%) and 15 (35.7%) had a deficit that accounted for greater than one-third of a vascular territory. FD-PBV maps were 100% sensitive and 81.3% specific to detect any CBV deficit and 100% sensitive and 62.9% specific to detect any CBV deficit of greater than one-third of a territory. CONCLUSIONS: PBV maps can be generated using FP systems. The average radiation dose is similar to a standard CTP examination. PBV maps have a high sensitivity for detecting CBV deficits defined by conventional CTP. PBV maps often overestimate the size of CBV deficits. We hypothesize that the FP protocol initiates PBV imaging prior to complete saturation of the blood volume in areas perfused via indirect pathways (ie, leptomeningeal collaterals), resulting in an overestimation of CBV deficits, particularly in the setting of large vessel occlusion.

Current methods of monitoring radiation exposure from CT.

Increased public and regulatory scrutiny of imaging-related radiation exposure requires familiarity with current dose-monitoring techniques and best practices. CT-related ionizing radiation exposure has been cited as the largest and fastest growing source of population-wide iatrogenic ionizing radiation exposure. Upcoming federal regulations require imaging centers to familiarize themselves with available dose-monitoring techniques and implement comprehensive strategies to track patient dose, with particular emphasis on CT. Because of institution-specific and vendor-specific technologies, there are significant barriers to adoption and implementation. In this article, the authors outline the core components of a universal dose-monitoring strategy and detail a few of the many available commercial platforms. In addition, the authors introduce a cloud-based hybrid model dose-tracking system with the goal of rapid implementation, multicenter scalability, real-time dose feedback for technologists, cumulative dose monitoring, and optional dose communication to patients and into the record; doing so results in improved patient loyalty, referring physician satisfaction, and opportunity for repeat business.

Hypothenar Hammer Syndrome in a Postal Worker.

We present the case of a 48-year-old woman with hypothenar hammer syndrome. Hypothenar hammer syndrome is caused by chronic repetitive trauma to the ulnar artery and superficial palmar arch. This syndrome was originally described in males working in occupations that involved repetitive blunt trauma including working with jackhammers. It is believed that the ulnar artery is repetitively damaged by blunt compression against the hamate. Our patient was a postal worker who frequently used a rubber stamper.