Whole-Body Clinical Applications of Digital Tomosynthesis.

With flat-panel detector mammography, radiography, and fluoroscopy systems, digital tomosynthesis (DT) has been recently introduced as an advanced clinical application that removes overlying structures, enhances local tissue separation, and provides depth information about structures of interest by providing high-quality tomographic images. DT images are generated from projection image data, typically using filtered back-projection or iterative reconstruction. These low-dose x-ray projection images are easily and swiftly acquired over a range of angles during a single linear or arc sweep of the x-ray tube assembly. DT is advantageous in a variety of clinical contexts, including breast, chest, head and neck, orthopedic, emergency, and abdominal imaging. Specifically, compared with conventional mammography, radiography, and fluoroscopy, as a result of reduced tissue overlap DT can improve detection of breast cancer, pulmonary nodules, sinonasal mucosal thickening, and bone fractures and delineation of complex anatomic structures such as the ostiomeatal unit, atlantoaxial joint, carpal and tarsal bones, and pancreatobiliary and gastrointestinal tracts. Compared with computed tomography, DT offers reduced radiation exposure, better in-plane resolution to improve assessment of fine bony changes, and less metallic artifact, improving postoperative evaluation of patients with metallic prostheses and osteosynthesis materials. With more flexible patient positioning, DT is also useful for functional, weight-bearing, and stress tests. To optimize patient management, a comprehensive understanding of the clinical applications and limitations of whole-body DT applications is important for improvement of diagnostic quality, workflow, and cost-effectiveness. Online supplemental material is available for this article. (©)RSNA, 2016.

Dual-energy subtraction radiography improves laryngeal delineation in patients with moderate to severe cervical spondylosis.

PURPOSE: To investigate the feasibility of dual-energy subtraction (DES) in patients with moderate-severe cervical spondylosis for improving delineation of the larynx on flat panel detector (FPD) radiography. MATERIALS AND METHODS: For 118 patients, we graded conventional/DES anterior-posterior views for delineation of the vocal cords, subglottis, and pyriform sinus using a 5-point scale and lateral views from conventional laryngeal FPD radiography to determine cervical spondylosis severity on a scale from 0 (none) to 3 (severe). We compared the delineation of each anatomical structure in both groups of grades 0-1 and grades 2-3 of spondylosis severity between conventional and DES methods and the improved delineation rate for each anatomical structure by DES compared to the conventional method between both groups. RESULTS: With DES, the delineation of each anatomical structure was significantly better than with conventional radiography for both groups (P < 0.0001). The improved delineation rate of the vocal cord and subglottis using DES was significantly higher in grades 2-3 than in grades 0-1 (P < 0.05), although there was no significant difference in the delineation rate of the pyriform sinus between the groups (P = 0.847). CONCLUSION: DES provides better delineation of the laryngeal anatomy than conventional FPD radiography predominantly in patients with moderate-severe cervical spondylosis.

Radiation dose of digital tomosynthesis for sinonasal examination: comparison with multi-detector CT.

OBJECTIVE: Using an anthropomorphic phantom, we have investigated the feasibility of digital tomosynthesis (DT) of flat-panel detector (FPD) radiography to reduce radiation dose for sinonasal examination compared to multi-detector computed tomography (MDCT). MATERIALS AND METHODS: A female Rando phantom was scanned covering frontal to maxillary sinus using the clinically routine protocol by both 64-detector CT (120 kV, 200 mAs, and 1.375-pitch) and DT radiography (80 kV, 1.0 mAs per projection, 60 projections, 40° sweep, and posterior-anterior projections). Glass dosimeters were used to measure the radiation dose to internal organs including the thyroid gland, brain, submandibular gland, and the surface dose at various sites including the eyes during those scans. We compared the radiation dose to those anatomies between both modalities. RESULTS: In DT radiography, the doses of the thyroid gland, brain, submandibular gland, skin, and eyes were 230 ± 90 µGy, 1770 ± 560 µGy, 1400 ± 80 µGy, 1160 ± 2100 µGy, and 112 ± 6 µGy, respectively. These doses were reduced to approximately 1/5, 1/8, 1/12, 1/17, and 1/290 of the respective MDCT dose. CONCLUSION: For sinonasal examinations, DT radiography enables dramatic reduction in radiation exposure and dose to the head and neck region, particularly to the lens of the eye.

Postoperative follow-up of olecranon fracture by digital tomosynthesis radiography.

Digital tomosynthesis with flat-panel detector radiography is a novel application that allows easy, swift volume data acquisition of any anatomical site of interest with arbitrary patient posture. A single sweep of the X-ray tube provides multiple tomographic images of high resolution. We present the first patient with olecranon fracture who underwent internal fixation and 1-year postoperative follow-up with tomosynthesis. The minimal metallic artifact by this modality successfully provided detailed information regarding the healing process of the fracture.

Self-reproduction of supramolecular giant vesicles combined with the amplification of encapsulated DNA.

The construction of a protocell from a materials point of view is important in understanding the origin of life. Both self-reproduction of a compartment and self-replication of an informational substance have been studied extensively, but these processes have typically been carried out independently, rather than linked to one another. Here, we demonstrate the amplification of DNA (encapsulated guest) within a self-reproducible cationic giant vesicle (host). With the addition of a vesicular membrane precursor, we observe the growth and spontaneous division of the giant vesicles, accompanied by distribution of the DNA to the daughter giant vesicles. In particular, amplification of the DNA accelerated the division of the giant vesicles. This means that self-replication of an informational substance has been linked to self-reproduction of a compartment through the interplay between polyanionic DNA and the cationic vesicular membrane. Our self-reproducing giant vesicle system therefore represents a step forward in the construction of an advanced model protocell.

Coronary artery spatial distribution, morphology, and composition of nonculprit coronary plaques by 64-slice computed tomographic angiography in patients with acute myocardial infarction.

Noninvasive identification of nonculprit lesions could improve preventive strategies for acute myocardial infarction (AMI). We assessed the morphology, composition, and spatial distribution of nonculprit coronary plaques in patients with AMI using computed tomographic angiography (CTA). A total of 64 patients with AMI underwent 64-slice CTA within 2 weeks after admission, and 162 symptomatic patients with stable angina pectoris (SAP) underwent CTA and stress myocardial perfusion imaging (MPI). Of these 226 patients, 16 were excluded from the analysis because of image artifacts. The mean number of nonculprit plaques per patient was 5.0 +/- 2.6 in the AMI group (n = 60), 4.2 +/- 2.6 in the SAP group with abnormal MPI findings (n = 67), and 1.1 +/- 1.3 in the SAP group with normal MPI findings (n = 83; p <0.01). Positive remodeling and low-attenuation plaques (<30 Hounsfield units) were more frequently observed in the AMI group (1.9 +/- 1.8) than in the SAP groups (0.6 +/- 0.9 with abnormal MPI findings and 0.2 +/- 0.4 with normal MPI findings; p <0.01). Within the AMI group, positive remodeling and low-attenuation plaques were present significantly more frequently in patients with metabolic syndrome than in those without (2.6 +/- 2.2 vs 1.4 +/- 1.4; p = 0.03) and was significantly more frequently distributed in the proximal segments of the left anterior descending artery (p <0.01). In conclusion, 64-slice CTA could provide promising information for preventive strategies by identifying nonculprit plaque morphology and zones at high risk of future events.

Quantitative measures of coronary stenosis severity by 64-Slice CT angiography and relation to physiologic significance of perfusion in nonobese patients: comparison with stress myocardial perfusion imaging.

UNLABELLED: Coronary stenosis severity by 64-slice CT angiography (CTA) is acceptably correlated with intravascular ultrasound. Stress myocardial perfusion imaging using SPECT is an established method for assessment of the functional significance of coronary stenosis. Our aim was to assess a clinical validation of quantitative measurements of coronary stenosis severity by 64-slice CTA and the relation to the physiologic significance of myocardial perfusion. METHODS: One hundred four patients with suspected coronary artery disease underwent 64-slice CTA and stress 201Tl SPECT. The stenosis severities of 105 coronary lesions assessed by CTA with sufficient image quality were compared with the results of stress 201Tl SPECT. The body mass index (BMI) of the patients was 23.8 kg/m2 (range, 21.1-25.6 kg/m2). RESULTS: Reversible defects began to increase progressively when the area of stenosis was at least 60%, and the prevalence of these reversible defects and their severity significantly increased as the degree of stenosis increased. When stenosis severity by CTA is < 60%, ischemia is seldom observed; when stenosis severity is > or =80%, ischemia is common (86%). For intermediate stenosis severity values of 60%-70%, the prevalence of reversible defects was 9 of 27 vessels (33%), and for stenosis severity values of 70%-80%, the prevalence was 20 of 37 vessels (54%). When evaluating the diagnostic accuracy of stenosis severity by CTA to identify patients with ischemia excluding all nonevaluable vessels, applying stenosis thresholds of >70% results in 79% sensitivity, 92% specificity, 66% positive predictive value, and 96% negative predictive value. A lesion minimal luminal cross-sectional area of < 3.7 mm2 was a good accurate cutoff value for significant coronary narrowing using stress SPECT, with a sensitivity of 88% and specificity of 83% by receiver-operating-characteristic analysis. CONCLUSION: Despite an excellent negative predictive value to rule out the presence of ischemia, 64-slice CTA alone is a poor discriminator of the functional significance of myocardial ischemia in a highly selected patient population with a low BMI.

Early validation study of 64-slice multidetector computed tomography for the assessment of myocardial viability and the prediction of left ventricular remodelling after acute myocardial infarction.

AIMS: We aim to validate the ability of multidetector computed tomography (MDCT) for assessing myocardial viability and predicting left ventricular (LV) remodelling after acute myocardial infarction (AMI). METHODS AND RESULTS: In 52 consecutive patients with first AMI, 64-slice MDCT without iodine re-injection was performed immediately following coronary stenting. Electrocardiogram-gated thallium-201 single-photon emission tomography was performed using QGS programs within 5 days and 6 months after onset. Among the 52 patients, 18 patients (Group A) showed transmural contrast-delayed enhancement on MDCT images, 20 patients (Group B) showed subendocardial contrast-delayed enhancement, and 14 patients (Group C) had no contrast-delayed enhancement. In the acute phase, peak creatine kinase-MB [497 (189-744), 182 (90-358), 85 (40-204) IU/mL, respectively, P = 0.0004] was significantly higher in Group A, while the incidence of myocardial blush grade 3 (22, 67, 75%, respectively, P = 0.001) and LV ejection fraction (41 +/- 7, 53 +/- 12, 62 +/- 11%, respectively, P < 0.0001) were significantly lower in Group A. During the 6-month period, LV remodelling (P = 0.001) and the number of rehospitalization for heart failure (P = 0.0017) were more significantly observed in Group A. CONCLUSION: Myocardial contrast-delayed enhancement patterns provide promising information regarding myocardial viability, LV remodelling, and prognosis in AMI.

Comparative analysis of the four rRNA operons in Finegoldia magna ATCC29328.

There are four rRNA operons rrnA, rrnB, rrnC and rrnD on the genome of Finegoldia magna (formerly Peptostreptococcus magnus) ATCC29328, which, in contrast to those of Clostridia, are dispersed around the chromosome. Using a BAC library we determined the nucleotide sequences and structures of all four operons, including their flanking regions, and performed comparative analyses. We identified putative boxA sequences in the operons, which should be required for rRNA transcription antitermination, as well as their respective tandem promoters, AT-rich UP elements in the upstream region and Rho-independent terminators in the downstream region. The mosaic features of the operons were revealed. Multiple tRNAs were identified in the downstream region of two operons, 18 in rrnC and 11 in rrnD. They were presumed to form transcription units together with rRNAs. rrnA and rrnB had repeat units with Rho-independent terminators instead of tRNAs in the downstream region. rrnB and rrnC were the most similar in rrn upstream promoter region. Focusing on the sequence variations of rRNA genes, rrnB alone was heterogeneous. In light of previous reports, we also assessed the correlation between intercistronic rRNA sequence differences and distances between the operons, but no positive correlation was seen in this strain.