Teresa Liang

The Evolving Role of the Radiologist: The Vancouver Workload Utilization Evaluation Study

PURPOSE The role of the present-day on-site hospital radiologist surpasses image interpretation-related duties. This study characterizes these workload activities, as well as quantifies the type of value-based interactions radiologists experience on a daily basis with allied health personnel. MATERIALS AND METHODS A prospective, observational, randomized study was performed across 3 hospitals in the fall of 2012. One month of observation of 14 staff radiologists was performed by a trained observer. The observer followed the subject radiologists throughout the workday, recording activities using a time and motion methodology. RESULTS Radiologists spent 36.4% of their time on image interpretation. The proportion of noninterpretative tasks was 43.8%, which includes activities such as protocolling requisitions, supervising and monitoring studies, performing image-guided procedures, consulting with physicians, and directly caring for patients. Total clinical productivity was 87.7%, and radiologists experienced, on average, 6 interactions per hour with other health personnel, of which over 81.2% directly influenced patient care in real time. CONCLUSION This study demonstrates a new framework of characterizing the type of work radiologists perform on a daily basis, which helps further define the evolving role of the present-day radiologist to other physicians, administrators, and policy makers. Furthermore, the on-site added value that radiologists deliver suggests that radiologists are central figures in the medical imaging department who are difficult to replace by off-site or nonradiologist image interpreters.

Iterative reconstructed ultra high pitch CT pulmonary angiography with cardiac bowtie-shaped filter in the acute setting: Effect on dose and image quality

PURPOSE To evaluate the effect of a cardiac bowtie-shaped filter in an ultra high pitch CTPA protocol at 100 kV on image quality and radiation dose. MATERIALS AND METHODS Retrospective study of 100 patients referred for CTPA. 50 patients scanned with a standard 100 kV protocol at pitch 2.8 (Protocol A) and 50 patients scanned with a 100 kV protocol at pitch 3.2 with a cardiac bowtie-shaped filter (Protocol B). All other scanning parameters kept constant. Images from both groups reconstructed with filtered back projection and iterative reconstruction. Central pulmonary vessel attenuation and background noise were quantitatively measured and signal-to-noise (SNR) and contrast-to-noise (CNR) were calculated. Two radiologists performed qualitative assessment grading visualization of the pulmonary vasculature and noise level. CTDIvol and DLP were recorded and effective dose was calculated. RESULTS CTDIvol, DLP and effective dose were significantly (p<0.0001) lower in Protocol B (2.3 ± 0.5 mGy, 78.4 ± 16.5 mGycm, 1.4 ± 0.3 mSy, respectively) compared to Protocol A (4.3 ± 0.5 mGy, 152.0 ± 19.6 mGycm, 2.7 ± 0.3 mSy, respectively). Protocol B had significantly (p<0.0001) higher noise than Protocol A (23.8 ± 6.9 HU vs 36.8 ± 7.3 HU) and lower SNR (11.8 ± 3.7 HU vs 19.2 ± 8.1 HU) and CNR (10.3 ± 3.7 HU vs 24.9 ± 13.4 HU) but there was no significant difference in the subjective visualization of the pulmonary vasculature (p=0.63). Furthermore, iterative reconstruction significantly (p<0.0001) improves image noise (29.4 ± 5.5 HU from 36.8 ± 7.3 HU). CONCLUSION The addition of a cardiac bowtie-shaped filter with an ultra high pitch CTPA protocol at 100 kV resulted in a 48% dose reduction without significantly affecting diagnostic image quality. In addition, the use of iterative reconstruction significantly improves image quality by reducing noise permitting the possibility for further dose reduction strategies.

Hypovolemic Shock Complex in the Trauma Setting: A Pictorial Review

Hypovolemia is defined as the physiological state of Taylor et al [5] initially described the HSC or hyporeduced blood or, more specifically, reduced plasma volume. When volume loss is severe, many homeostatic mechanisms serve to maintain adequate tissue perfusion to critical organs, such as the brain and the heart. These compensatory mechanisms can result in a severe reduction of vascular perfusion and oxygen delivery to numerous other vital organs, such as the liver and the kidneys, which may ultimately lead to multiorgan failure. Key steps in the initial management of hypovolemic shock include determining the severity of volume loss, appropriate volume resuscitation, and accurate identification of the underlying cause. The severity of shock can be graded based on the scale of derangement in vital signs, such as heart rate and blood pressure, and by the presence and severity of clinical signs and symptoms, such as pallor, tachypnea, and a reduced level of consciousness. Classification schemes often use a 4or 6-point scale and have been shown to improve patient management and outcome [1e3]. The subgroups and major causes of hypovolemic shock are summarized in Table 1 [4]. In contemporary practice, patients with hypovolemic shock related to hemorrhagic traumatic causes are frequently evaluated by using computed tomography (CT). Although the primary aim of CT in patients with hemorrhagic traumatic shock is to identify the exact site of blood loss and to direct appropriate treatment of traumatic injuries, accurate recognition of a constellation of secondary CT findings termed the hypovolemic shock complex (HSC) also allows radiologists to contribute significantly towards the clinical grading of shock severity.

Review of Multidetector Computed Tomography Angiography as a Screening Modality in the Assessment of Blunt Vascular Neck Injuries

Blunt vascular neck injuries (BVNI), previously thought to be rare, have demonstrated increasing incidence rates in recent literature and are associated with significant mortality and morbidity. A radiologist needs to efficiently recognize these injuries on preliminary screening to enable initiation of early management. When initiation of accurate management is started promptly, decreased rates of postinjury complications, for example, stroke, have been demonstrated. This article reviews the incidence, pathophysiology, and rationale for screening for these BVNI injuries. The utility of computed tomography angiography (CTA) as the potential new criterion standard as the screening and follow-up imaging modality for BVNI will be discussed. The application of new multidetector CTA techniques available, such as dual-energy CT and iterative reconstruction, are also reviewed. In addition, the characteristic imaging findings on CTA and the associated Denver Grading scale for BVNI will be reviewed to allow readers to become familiar with the injury patterns and to understand the prognostic and clinical implications, respectively. Examples of the spectrum of injuries, potential injury mimics, and different artifacts on multidetector CTA are shown to help familiarize readers and allow them to successfully and confidently recognize a true BVNI.

Imaging of Blunt Cerebrovascular Injuries

e B cerebrovascular injuries (BCVI) is a collective term, encompassing injuries to one or both of the carotid and vertebral arteries, often secondary to direct trauma. Despite the previous belief that BCVI are relatively rare with estimated incidence rates as low as 0.1% in all blunt trauma cases,1 recent literature presented herein reports a significantly higher incidence of these injuries reported to be 1.25% and the incidence has been shown to increase up to 2.7% in patients with Injury Severity Score 16.2 Unfortunately, BCVI can present with a wide spectrum of symptoms, ranging from being asymptomatic to death. In fact, nonspecific signs and symptoms in the setting of BCVI, in part, contribute to associated high morbidity and mortality. Mortality rates as high as 59% have been reported previously.3 Often, nitially asymptomatic BCVI concur with a delayed diagnosis and treatment, hich further contributes to poor prognostic outcomes. Therefore, adequate creening criteria, appropriate imaging modalities, and prompt treatment nitiation must be routinely implemented to attenuate morbidity and morality rates. This article aims to discuss the incidence rate of BCVI in an attempt to ustify the importance of appropriate screening protocols. Literature pertainng to imaging modalities used in the setting of BCVI, as well as proposed reatment approaches, are summarized with representative cases.

Stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma: imaging evaluation post treatment

Surgical resection, when feasible, is the standard of care for hepatocellular carcinoma. However, many tumours are not resectable at the time of diagnosis. Recently, stereotactic body radiation therapy (SBRT) has emerged as a non-invasive local therapy for both non-resectable primary hepatic malignancies as well as hepatic metastases. Knowledge of the expected hepatic parenchymal appearance post treatment, as well as potential pitfalls and complications, is essential for accurate evaluation of treatment response. This pictorial review provides a fundamental description of the SBRT technique, outlines the expected cross-sectional imaging appearances of tumour response, and highlights potential pitfalls in interpretation. The expected liver parenchymal changes post-SBRT are also reviewed, along with some common radiation-induced complications.

Clinical Utility of Dual-Energy CT Analysis of Bone Marrow Edema in Acute Wrist Fractures

OBJECTIVE The purpose of this study is to determine the utility of dual-energy CT (DECT) for assessing carpal fractures and to obtain an attenuation value cutoff (in Hounsfield units) to identify bone marrow edema due to an acute carpal fracture. MATERIALS AND METHODS In this retrospective study, 24 patients who presented with wrist fractures from September 3, 2014, through March 9, 2015, underwent imaging with DECT (80 and 140 kVp). Using the three-material decomposition algorithm specific for virtual noncalcium to construct images, two radiologists identified carpal fractures and associated bone marrow edema. Readers noted the attenuation at areas with and without bone marrow edema. The cutoff value was obtained by ROC analysis and was internally validated on 13 separate patients with suspected wrist fractures. A p < 0.05 was considered statistically significant. RESULTS CT attenuation was significantly higher in areas of bone marrow edema than in areas without it (p < 0.0001, t test). A cutoff of 5.90 HU allows detection of bone marrow edema associated with acute wrist fractures with 100% sensitivity and 99.5% specificity, compared with visual DECT interpretation. In the 13 validation cases, the cutoff of 5.90 HU identified bone marrow edema with 100% accuracy, compared with visual interpretation. Kappa values were 0.83 between the two readings by reader 1, and 0.73 and 0.96 comparing the two readings of reader 1 with the reading by reader 2. CONCLUSION DECT is a useful tool for identifying bone marrow edema in the setting of acute wrist fractures, providing an alternative to MRI. A cutoff value of 5.90 HU can be used for accurate diagnosis and exclusion of carpal fractures.