Imaging of the aortic root on high-pitch non-gated and ECG-gated CT: awareness is the key!

The aortic pathologies are well recognized on imaging. However, conventionally cardiac and proximal aortic abnormalities were only seen on dedicated cardiac or aortic studies due to need for ECG gating. Advances in CT technology have allowed motionless imaging of the chest and abdomen, leading to an increased visualization of cardiac and aortic root diseases on non-ECG-gated imaging. The advances are mostly driven by high pitch due to faster gantry rotation and table speed. The high-pitch scans are being increasingly used for variety of clinical indications because the images are free of motion artifact (both breathing and pulsation) as well as decreased radiation dose. Recognition of aortic root pathologies may be challenging due to lack of familiarity of radiologists with disease spectrum and their imaging appearance. It is important to recognize some of these conditions as early diagnosis and intervention is key to improving prognosis. We present a comprehensive review of proximal aortic anatomy, pathologies commonly seen at the aortic root, and their imaging appearances to familiarize radiologists with the diseases of this location.

Prospective Comparison of Reduced-Iodine-Dose Virtual Monochromatic Imaging Dataset From Dual-Energy CT Angiography With Standard-Iodine-Dose Single-Energy CT Angiography for Abdominal Aortic Aneurysm.

OBJECTIVE: The purpose of this study was to compare the image quality of reduced-iodine-dose single-source dual-energy CT angiography (CTA) with that of standard-iodine-dose single-energy CTA in examinations of patients with abdominal aortic aneurysm and to assess the effect of the concentration of iodinated contrast medium on intravascular enhancement and image quality of reduced-iodine-dose CTA. SUBJECTS AND METHODS: In a prospective randomized clinical trial, 66 consecutively registered patients with abdominal aortic aneurysm who had previously undergone single-energy CTA (30-37 g I) underwent follow-up CTA at a reduced dose (21-27 g I) of iodinated contrast medium of either 270 mg I/mL (n = 33) or 320 mg I/mL (n = 33). Two readers independently evaluated virtual monochromatic imaging datasets (40-140 keV) and single-energy CTA images for image quality and noise and their preference for optimal energy virtual monochromatic imaging dataset. A value of p < 0.05 was considered statistically significant. RESULTS: All 66 dual-energy CTA examinations were rated diagnostic with mean image quality and image noise scores of 4.8 and 4.5 for reader 1 and 3.8 and 3.4 for reader 2 compared with single-energy CTA results of 4.5 and 4.2 for reader 1 and 4.5 and 4.1 for reader 2. Low-energy virtual monochromatic images (40-60 keV) from reduced-iodine-dose (28%) dual-energy CTA had significantly higher intravascular aortic attenuation (26-185%) and contrast-to-noise ratio (CNR) (20-25%) than standard-iodine-dose single-energy CTA images (p < 0.0001). No significant difference was found between patients who received 270 and those who received 320 mg I/mL with respect to intravascular aortic attenuation (p = 0.6331) or CNR (p = 0.9775). CONCLUSION: Low-energy virtual monochromatic imaging datasets from reduced-iodine (24 g I) single-source dual-energy CTA of the abdomen provide up to 185% higher attenuation and 25% higher CNR than standard-iodine-dose (33.3 g I) single-energy CTA while offering a wide range of energy settings irrespective of the concentration of IV contrast medium used.

Material Separation Using Dual-Energy CT: Current and Emerging Applications.

Dual-energy (DE) computed tomography (CT) offers the opportunity to generate material-specific images on the basis of the atomic number Z and the unique mass attenuation coefficient of a particular material at different x-ray energies. Material-specific images provide qualitative and quantitative information about tissue composition and contrast media distribution. The most significant contribution of DE CT-based material characterization comes from the capability to assess iodine distribution through the creation of an image that exclusively shows iodine. These iodine-specific images increase tissue contrast and amplify subtle differences in attenuation between normal and abnormal tissues, improving lesion detection and characterization in the abdomen. In addition, DE CT enables computational removal of iodine influence from a CT image, generating virtual noncontrast images. Several additional materials, including calcium, fat, and uric acid, can be separated, permitting imaging assessment of metabolic imbalances, elemental deficiencies, and abnormal deposition of materials within tissues. The ability to obtain material-specific images from a single, contrast-enhanced CT acquisition can complement the anatomic knowledge with functional information, and may be used to reduce the radiation dose by decreasing the number of phases in a multiphasic CT examination. DE CT also enables generation of energy-specific and virtual monochromatic images. Clinical applications of DE CT leverage both material-specific images and virtual monochromatic images to expand the current role of CT and overcome several limitations of single-energy CT. (©)RSNA, 2016.

Autologous breast reconstruction: preoperative magnetic resonance angiography for perforator flap vessel mapping.

BACKGROUND: Selection of a vascular pedicle for autologous breast reconstruction is time consuming and depends on visual evaluation during the surgery. Preoperative imaging of donor site for mapping the perforator artery anatomy greatly improves the efficiency of perforator selection and significantly reduces the operative time. In this article, we present our experience with magnetic resonance angiography (MRA) for perforator vessel mapping including MRA technique and interpretation. METHODS: We have performed over 400 MRA examinations from August 2008 to August 2013 at our institution for preoperative imaging of donor site for mapping the perforator vessel anatomy. Using our optimized imaging protocol with blood pool magnetic resonance imaging contrast agents, multiple donor sites can be imaged in a single MRA examination. Following imaging using the postprocessing and reporting tool, we estimated incidence of commonly used perforators for autologous breast reconstruction. RESULTS: In our practice, anterior abdominal wall tissue is the most commonly used donor site for perforator flap breast reconstruction and deep inferior epigastric artery perforators are the most commonly used vascular pedicle. A thigh flap, based on the profunda femoral artery perforator has become the second most used flap at our institution. In addition, MRA imaging also showed evidence of metastatic disease in 4% of our patient subset. CONCLUSION: Our MRA technique allows the surgeons to confidently assess multiple donor sites for the best perforator and flap design. In conclusion, a well-performed MRA with specific postprocessing provides an accurate method for mapping perforator vessel, at the same time avoiding ionizing radiation.

Oncologic applications of dual-energy CT in the abdomen.

Dual-energy computed tomographic (DECT) technology offers enhanced capabilities that may benefit oncologic imaging in the abdomen. By using two different energies, dual-energy CT allows material decomposition on the basis of energy-dependent attenuation profiles of specific materials. Although image acquisition with dual-energy CT is similar to that with single-energy CT, comprehensive postprocessing is able to generate not only images that are similar to single-energy CT (SECT) images, but a variety of other images, such as virtual unenhanced (VUE), virtual monochromatic (VMC), and material-specific iodine images. An increase in the conspicuity of iodine on low-energy VMC images and material-specific iodine images may aid detection and characterization of tumors. Use of VMC images of a desired energy level (40-140 keV) improves lesion-to-background contrast and the quality of vascular imaging for preoperative planning. Material-specific iodine images enable differentiation of hypoattenuating tumors from hypo- or hyperattenuating cysts and facilitate detection of isoattenuating tumors, such as pancreatic masses and peritoneal disease, thereby defining tumor targets for imaging-guided therapy. Moreover, quantitative iodine mapping may serve as a surrogate biomarker for monitoring effects of the treatment. Dual-energy CT is an innovative imaging technique that enhances the capabilities of CT in evaluating oncology patients.

Morphine three-dimensional T1 gadoxetate MR cholangiography of potential living related liver donors.

PURPOSE: To assess low-dose morphine for distension and improved visualization of intrahepatic bile ducts on T1 MR cholangiography (MRC) in preoperative imaging of potential liver donors. MATERIALS AND METHODS: Sixty-nine consecutive potential living related liver donors (mean age, 39 years; age range, 20 to 59 years) referred for pre-transplant MRI evaluation were evaluated without (n=30) or with (n=39) intravenous morphine injection (0.04 mg/kg). Morphine was injected pre-MRI while establishing intravenous access to allow ∼1 h for biliary distension before T1 MRC. Three radiologists reviewed intrahepatic biliary branch order visualization, common bile duct (CBD) diameter, and overall image quality. In 25 patients undergoing liver donation surgery, T1 MRC findings were correlated with intraoperative findings. This retrospective study was approved by the institutional review board. RESULTS: Biliary visualization was improved post-morphine administration with biliary duct branch order visualization score of 3.2 and 3.3 at 45 and 60 min, respectively, compared with 2.7 without morphine (P<0.002); CBD diameter measured 5.3 and 5.5 versus 4.1 mm (P<0.005), and overall image quality score was 2.4 and 2.6 versus 1.8 (P<0.0006). Operative notes confirmed T1 MRC findings in 6/11 donors without morphine and 14/14 donors with morphine. CONCLUSION: Intravenous low-dose morphine distends and improves visualization of bile ducts on T1 gadoxetate MRC.

Improved hepatic arterial phase MRI with 3-second temporal resolution.

PURPOSE: To assess 3-s temporal resolution for arterial phase bolus timing on dynamic liver MRI. MATERIALS AND METHODS: One hundred consecutive patients undergoing fluoro-triggered dynamic gadoxetate enhanced liver MRI with standard Cartesian k-space LAVA (Liver Acquisition with Volume Acceleration) were compared with 61 consecutive patients imaged using spiral k-space LAVA reconstructed at 3-s temporal resolution with sliding window reconstruction. For qualitative analysis, bolus timing, hepatic artery branch order visualized, and overall image quality were evaluated. For quantitative analysis, contrast to noise ratio between aorta and liver parenchyma, aorta and portal vein, and signal intensity ratio between aorta and liver parenchyma were calculated. RESULTS: MR fluoroscopy triggered single phase standard LAVA produced optimal arterial phase timing in 35% patients, compared with 88% with Spiral LAVA (P < 0.0001). Spiral LAVA had superior bolus timing scoring 2.0, compared with 1.0 with standard LAVA (P < 0.0001). Overall image quality and hepatic artery branch order visualization scoring were superior on spiral LAVA, compared with standard LAVA (P < 0.001). The aorta to liver parenchyma signal intensity ratio was also superior on spiral LAVA, compared with standard LAVA (2.8 vs. 2.2; P < 0.001). CONCLUSION: Dynamic liver MRI bolus timing improves using 3-s temporal resolution.

C3-C4 spondyloptosis without neurological deficit-a case report.

BACKGROUND CONTEXT: Traumatic spondyloptosis of the cervical spine is usually associated with a complete, or rarely a partial, neurological deficit. Traumatic spondyloptosis with bipedicular fracture of the C3 vertebra is uncommon. To the best of the authors' knowledge, there is no report in the literature of bipedicular fracture of C3 with spondyloptosis of C3 over C4 with no neurological deficit. Literature is not clear about the role of preoperative traction in neurologically intact patients, and most authors advise both anterior and posterior fixation for cervical spondyloptosis. PURPOSE: To report a case of C3-C4 spondyloptosis with C1 and C2 posterior arch fractures with no neurological deficit and its management strategy and underline the fact that closed reduction and limited anterior fusion can preserve the motion segment of cervical spine at other fractured levels and give a stable cervical column with good long-term results. STUDY DESIGN: A case report with review of the literature. METHODS: A 35-year-old man fell from a height with hyperextension-compression injury to the cervical spine. The patient suffered fracture of the posterior elements of C1-C3 along with spondyloptosis of C3 over C4 without any neurological deficit. The patient was treated with an awake nasotracheal intubation with gradual cervical traction under fluoroscopic guidance to acceptable alignment followed by anterior cervical fusion at C3-C4. RESULTS: At 24 months' follow-up, the C3-C4 level fused completely with fracture healing at C1 and C2. The patient remained asymptomatic with normal neurological examination and near complete cervical motion. The patient returned to his preinjury job and recreational activities. CONCLUSIONS: A case of C3-C4 spondyloptosis with associated C1-C2 posterior arch fracture is reported. The patient can present without neurological deficit if associated with a fracture of the posterior elements. Spondyloptosis without neurological deficit can be treated with gradual reduction under fluoroscopic guidance. A limited anterior-only fusion at the spondyloptosis level can provide good long-term results with preservation of other motion segments.

Disseminated cysticercosis with pulmonary and cardiac involvement.

Pulmonary and cardiac involvement by cysticercosis is extremely rare, and is usually asymptomatic. We report the case of a 19-year-old boy who presented with a history of headache and vomiting and was found to have disseminated cysticercosis with pulmonary and cardiac involvement; the emphasis is on the rare occurrence of pulmonary, cardiac, pancreatic, intraocular, and extradural spinal canal involvement in the same patient. This case demonstrates the extent to which cysticercosis can be disseminated.