Garry Choy

Radiation dose reduction with Sinogram Affirmed Iterative Reconstruction technique for abdominal computed tomography.

Purpose The objective of this study was to assess the effect of Sinogram Affirmed Iterative Reconstruction (SAFIRE) and filtered back-projection (FBP) techniques on abdominal computed tomography (CT) performed with 50% and 75% radiation dose reductions. Methods Twenty-four patients (mean age, 64 ± 14 years; male-female ratio, 10:14) gave informed consent for an institutional review board–approved prospective study involving acquisition of additional research images through the abdomen on 128-slice multi–detector-row CT (SOMATOM Definition Flash) at quality reference mAs of 100 (50% lower dose) and 50 (75% lower dose) over a scan length of 10 cm using combined modulation (CARE Dose 4D). Standard-of-care abdominal CT was performed at 200 quality reference mAs, with remaining parameters held constant. The 50- and 100-mAs data sets were reconstructed with FBP and at 4 SAFIRE settings (S1, S2, S3, S4). Higher number of SAFIRE settings denotes increased strength of the algorithm resulting in lower image noise. Two abdominal radiologists independently compared the FBP and SAFIRE images for lesion number, location, size and conspicuity, and visibility of small structures, image noise, and diagnostic confidence. Objective noise and Hounsfield units (HU) were measured in the liver and the descending aorta. Results All 43 lesions were detected on both FBP and SAFIRE images. Minor blocky, pixelated appearance of 50% and 75% reduced dose images was noted at S3 and S4 SAFIRE but not at S1 and S2 settings. Subjective noise was suboptimal in both 50% and 75% lower-dose FBP images but was deemed acceptable on all SAFIRE settings. Sinogram Affirmed Iterative Reconstruction images were deemed acceptable in all patients at 50% lower dose and in 22 of 24 patients at 75% lower dose. As compared with 75% reduced dose FBP, objective noise was lower by 22.8% (22.9/29.7), 35% (19.3/29.7), 44.3% (16.7/29.3), and 54.8% (13.4/29.7) on S1 to S4 settings, respectively (P < 0.001). Conclusions Sinogram Affirmed Iterative Reconstruction–enabled reconstruction provides abdominal CT images without loss in diagnostic value at 50% reduced dose and in some patients also at 75% reduced dose.

Differentiation of Malignant Thrombus from Bland Thrombus of the Portal Vein in Patients with Hepatocellular Carcinoma: Application of Diffusion-weighted MR Imaging

PURPOSE To investigate the utility of diffusion-weighted (DW) imaging in distinguishing bland thrombus from neoplastic thrombus in the portal vein in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS In this retrospective institutional review board-approved HIPAA-complaint study, the imaging results in 25 patients (16 men [average age, 62.3 years; range, 35-75 years] and nine women [average age, 58.4 years; range, 32-69 years]; overall average age, 60.1 years; range, 32-75 years) with HCC and portal vein thrombosis who were examined with both contrast material-enhanced computed tomography (CT) and 1.5-T magnetic resonance (MR) imaging were reviewed. Axial echo-planar two-dimensional DW imaging was performed by using b values of 50, 400, and 800 sec/mm(2). A thrombus was considered neoplastic if it expanded the vessel or enhanced on the dynamic CT and MR images; otherwise it was considered bland. The signal intensity (SI) of the thrombus and HCC lesions in the same patients was compared on DW images. The results were evaluated by using the Fisher exact test. The apparent diffusion coefficients (ADCs) of HCC and thrombus were used to compute the ratio of the ADC of the thrombus to the ADC of the tumor. RESULTS On DW images, 15 of 19 neoplastic thrombi demonstrated same SI and four showed lower SI than the primary HCC. Each of the six bland thrombi had lower SI than the primary HCC (P < .001). The mean ADC of HCC and thrombus in the neoplastic thrombus group was 0.87 x 10(-3) mm(2)/sec and 0.88 x 10(-3) mm(2)/sec, respectively (P = .45). The ADC of the bland thrombus was 2.89 x 10(-3) mm(2)/sec, significantly higher than the ADC of the HCC (1.0 x 10(-3) mm(2)/sec, P < .0003). The ratio of the ADC of the thrombus to the ADC of the tumor in the bland thrombus group was 2.9 compared with 0.998 in the neoplastic group (P = .0003). CONCLUSION DW imaging enables discrimination between bland and neoplastic portal vein thrombi when the ratio of the ADC of the thrombus to the ADC of HCC was lower than 2 and when the thrombi showed similar SI as the primary HCC when qualitative analysis was performed.

Creating a Patient-Centered Radiology Practice Through the Establishment of a Diagnostic Radiology Consultation Clinic

OBJECTIVE The purposes of this study were to assess the feasibility of and to create a referral mechanism for a diagnostic radiology consultation clinic. SUBJECTS AND METHODS A pilot program was instituted with patients from a single primary care clinic over a 3-week period. Patients with findings of common problems at routine imaging, such as atherosclerosis, emphysema, and hepatic steatosis, were eligible to participate. As the patients arrived for their routine primary care visits, office staff informed them of the opportunity to formally meet with a radiologist to review their most recent imaging findings. The office staff of the primary care clinic then contacted the radiologist covering the diagnostic radiology consultation clinic to schedule a consultation. A survey was administered before and after the session. RESULTS Twenty-two patients participated (88% participation rate). Participants rated the consultation as very helpful (mean, 4.8 on 1-5 scale), and all participants would take the opportunity to review studies with the radiologist again. Significantly more patients preferred the involvement of the radiologist in communicating the results of an imaging examination after the consultation compared with before the consultation (p = 0.001). After the consultation session, patients had significantly improved understanding of a radiologists role (p = 0.004), and all participants were able to correctly identify the radiologist as a physician who interprets medical images. CONCLUSION A referral mechanism for a diagnostic radiology consultation clinic can be effectively integrated into the everyday workflow of both the referring physician and the radiologist. The consultations are useful to patients and help to increase their awareness of the role of the radiologist.

Radiologists' role in the communication of imaging examination results to patients: perceptions and preferences of patients.

OBJECTIVE It has been suggested that radiology reporting practices would be improved if radiologists were to discuss the results of an examination directly with the patient. The attitudes and preferences of patients with regard to direct communication with the radiologist are not well-defined. The purpose of this study was to survey patients about their preferred method of receiving radiologic results. MATERIALS AND METHODS An anonymous survey was distributed to adult patients undergoing contrast-enhanced CT or MRI over a 2-week period in June 2013. RESULTS The response rate was 58.4% (642 responses). For normal examination results, the preferred mode of communication was a telephone call from the ordering physician (34.1%); only 12% of respondents opted for a telephone call from the radiologist, and 2.6% chose a face-to-face meeting with the radiologist. For abnormal test results, the preferred mode of communication was also a telephone call from the ordering physician (49.8%); 14.4% of respondents selected a telephone call from the radiologist, and 8.3% chose a face-to-face meeting with the radiologist. Patients preferred receiving very detailed versions of radiology reports for both normal (46.4%) and abnormal (81.8%) test results. Patients also expressed a desire to have access to at least key images from their examinations. CONCLUSION Patients prefer receiving both normal and abnormal examination results from the physicians who ordered the examination rather than the radiologist. They also prefer to receive very detailed examination results rather than a brief summary in lay terms.

Recent Measures to Improve Radiology Reporting: Perspectives From Primary Care Physicians

PURPOSE There is considerable interest in improving radiology reporting practices. It has been suggested recently that reporting practices could be improved by more direct involvement of radiologists in delivering results to patients and by making clear recommendations within the radiology report. The opinions of primary care physicians about these initiatives are not well known. The authors surveyed primary care physicians to better understand their views. METHODS An online survey was distributed to 229 primary care physicians through an internal list server, and responses were collected confidentially. RESULTS There were 100 responses (a 43.6% response rate). The majority of respondents were satisfied with radiology reporting and recommendations in general. Ninety-five percent of respondents felt that ordering physicians should deliver the results of examinations. No respondents felt that radiologists should deliver results directly to patients. Ninety-four percent of respondents felt medicolegally obligated by recommendations made by radiologists within their reports. Twenty-three percent of respondents felt more medicolegally obligated if the recommendation is set apart from the clinical impression, while 58% of respondents felt less medicolegally obligated if qualifying language is added to the recommendation. CONCLUSIONS Primary care physicians prefer to deliver the results of examinations themselves and feel medicolegally obligated by recommendations within radiology reports, even though this seems to be influenced by the wording and location of the recommendations within reports. Radiologists should consider these factors when contemplating changes in reporting practices.

ACR Appropriateness Criteria on acute pelvic pain in the reproductive age group.

Premenopausal women who present with acute pelvic pain frequently pose a diagnostic dilemma, exhibiting nonspecific signs and symptoms, the most common being nausea, vomiting, and leukocytosis. Diagnostic considerations encompass multiple organ systems, including obstetric, gynecologic, urologic, gastrointestinal, and vascular etiologies. The selection of imaging modality is determined by the clinically suspected differential diagnosis. Thus, a careful evaluation of such a patient should be performed and diagnostic considerations narrowed before a modality is chosen. Transvaginal and transabdominal pelvic sonography is the modality of choice when an obstetric or gynecologic abnormality is suspected, and computed tomography is more useful when gastrointestinal or genitourinary pathology is more likely. Magnetic resonance imaging, when available in the acute setting, is favored over computed tomography for assessing pregnant patients for nongynecologic etiologies because of the lack of ionizing radiation.

Ultra-low dose abdominal MDCT: using a knowledge-based Iterative Model Reconstruction technique for substantial dose reduction in a prospective clinical study.

PURPOSE To assess lesion detection and image quality parameters of a knowledge-based Iterative Model Reconstruction (IMR) in reduced dose (RD) abdominal CT examinations. MATERIALS AND METHODS This IRB-approved prospective study included 82 abdominal CT examinations performed for 41 consecutive patients (mean age, 62 ± 12 years; F:M 28:13) who underwent a RD CT (SSDE, 1.5 mGy ± 0.4 [∼ 0.9 mSv] at 120 kV with 17-20 mAs/slice) immediately after their standard dose (SD) CT exam (10 mGy ± 3 [∼ 6 mSv] at 120 kV with automatic exposure control) on 256 MDCT (iCT, Philips Healthcare). SD data were reconstructed using filtered back projection (FBP). RD data were reconstructed with FBP and IMR. Four radiologists used a five-point scale (1=image quality better than SD CT to 5=image quality unacceptable) to assess both subjective image quality and artifacts. Lesions were first detected on RD FBP images. RD IMR and RD FBP images were then compared side-by-side to SD-FBP images in an independent, randomized and blinded fashion. Friedmans test and intraclass correlation coefficient were used for data analysis. Objective measurements included image noise and attenuation as well as noise spectral density (NSD) curves to assess the noise in frequency domain were obtained. In addition, a low-contrast phantom study was performed. RESULTS All true lesions (ranging from 32 to 55) on SD FBP images were detected on RD IMR images across all patients. RD FBP images were unacceptable for subjective image quality. Subjective ratings showed acceptable image quality for IMR for organ margins, soft-tissue structures, and retroperitoneal lymphadenopathy, compared to RD FBP in patients with a BMI ≤ 25 kg/m(2) (median-range, 2-3). Irrespective of patient BMI, subjective ratings for hepatic/renal cysts, stones and colonic diverticula were significantly better with RD IMR images (P<0.01). Objective image noise for RD FBP was 57-66% higher, and for RD IMR was 8-56% lower than that for SD-FBP (P<0.01). NSD showed significantly lower noise in the frequency domain with IMR in all patients compared to FBP. CONCLUSION IMR considerably improved both objective and subjective image quality parameters of RD abdominal CT images compared to FBP in patients with BMI less than or equal to 25 kg/m(2).

Pertinent reportable incidental cardiac findings on chest CT without electrocardiography gating: review of 268 consecutive cases.

Background Pertinent reportable cardiac findings on non-electrocardiography (ECG)-gated chest CT examinations have become easier to detect given recent advancements in multidetector CT technology. However, those findings are easily overlooked on routine chest CT without ECG gating given residual inherent cardiac motion artifact and non-cardiac indications. Purpose To describe and quantify the types of pertinent reportable cardiac findings that can be detected on chest CT examinations without ECG gating and evaluate how often they were reported. Material and Methods Two radiologists retrospectively reviewed (blinded to the original interpretation) 268 consecutive routine adult chest CT examinations without ECG gating for the presence of pertinent reportable cardiac findings. Retrospective interpretations were then compared with the original radiological reports. Results One hundred and sixty-three patients (61%) had pertinent reportable cardiac findings. The findings encountered included: coronary artery disease (n = 131; 80.0%), coronary artery bypass grafts (n = 10; 6.1%), left ventricular aneurysm (n = 1; 0.6%), valve calcification (n = 131; 80.0%), valve repair/replacement (n = 5; 3.1%), pericardial effusion (n = 33; 20.2%), left atrial appendage thrombus (n = 1; 0.6%), cardiac mass (n = 1; 0.6%), and cardiac chamber enlargement (n = 29; 17.8%). On the original radiological reports 22.3% of the pertinent reportable cardiac findings, detected by the two radiologists retrospectively, were not reported. Conclusion Detection of pertinent reportable cardiac findings on routine chest CT examinations without ECG gating is possible. The high volume of chest CT examinations without ECG gating represents an opportunity for radiologists to comment on the presence or absence of cardiac disease which may influence future clinical decisions.

Embryology and Developmental Defects of the Interatrial Septum

OBJECTIVE The various types of atrial septal defects (ASDs) can be differentiated on the basis of their imaging appearance on MDCT. CONCLUSION It is fundamental for the cardiac imager to understand the embryologic development of the interatrial septum and the morphogenic differences of ASDs.

Effect of localizer radiograph on radiation dose associated with automatic exposure control: human cadaver and patient study.

Purpose To evaluate the effect of localizing radiograph on computed tomography (CT) radiation dose associated with automatic exposure control with a human cadaver and patient study. Materials and Methods Institutional review board approved the study with a waiver of informed consent. Two chest CT image series with fixed tube current and combined longitudinal-angular automatic exposure control (AEC) were acquired in a human cadaver (64-year-old man) after each of the 8 combinations of localizer radiographs (anteroposterior [AP], AP lateral, AP-posteroanterior [PA], lateral AP, lateral PA, PA, PA-AP, and PA lateral). Applied effective milliampere second, volume CT dose index (CTDIvol) and image noise were recorded for all 24-image series. Volume CT dose indexes were also recorded in 20 patients undergoing chest and abdominal CT after PA and PA-lateral radiographs with the use of AEC. Data were analyzed using analysis of variance and linear correlation tests. Results With AEC, the CTDIvol fluctuates with the number and projection of localizer radiographs (P < 0.0001). Lowest CTDIvol values are seen when 2 orthogonal localizer radiographs are acquired, whereas highest values are seen when single PA or AP-PA projection localizer radiographs are acquired for planning (P < 0.0001). In 20 patients, CT scanning with AEC after acquisition of 2 orthogonal projection localizer radiographs was associated with significant reduction in radiation dose compared to PA projection radiographs alone (P < 0.0001). Conclusions When scanning with AEC, acquisition of 2 orthogonal localizer radiographs is associated with lower CTDIvol compared to a single localizer radiograph.