Assessment of Intramyocardial Fat Content Using Computed Tomography: Is There a Relationship With Obesity?

BACKGROUND: Fat deposition in the liver and the skeletal muscle are linked to cardiovascular risk factors. Fat content in tissues can be estimated by measuring attenuation on noncontrast computed tomography (CT). Quantifying intramyocardial fat content is of interest as it may be related to myocardial dysfunction or development of heart failure. We hypothesized that myocardial fat content would correlate with severity of obesity, liver fat, and components of the metabolic syndrome. METHODS: We measured attenuation values on 121 noncontrast CT scans from the spleen, liver, erector spinae muscle, and myocardial septum. A chart review was performed for patient demographics and clinical characteristics. We tested for correlations between attenuation values in each of the tissues and various clinical parameters. RESULTS: We studied 78 females and 43 males, with a mean age of 54.5±11.2 years. Weak, but significant inverse Spearman correlation between body mass index and attenuation values were found in the liver (ρ=-0.228, P=0.012), spleen (ρ=-0.225, P=0.017), and erector spinae muscle (ρ=-0.211, P=0.022) but not in the myocardial septum (ρ=0.012, P=0.897). Mean attenuation in the nonobese group versus obese group (body mass index >30 kg/m2) were 41.1±5.0 versus 42.3±6.9 (P=0.270) in myocardial septum, 56.1±8.7 versus 51.7±10.9 (P=0.016) in the liver, 43.9±8.9 versus 40.1±10.4 (P=0.043) in the spleen, and 41.7±8.3 versus 39.0±8.8 (P=0.087) in the erector spinae muscle. CONCLUSIONS: Although CT is a theoretically appealing modality to assess fat content of the myocardium, we did not find a relationship between myocardial CT attenuation and obesity, or other cardiovascular risk factors. These findings suggest that the degree of myocardial fat accumulation in obesity or metabolic syndrome is too small to be detected with this modality.

Photodynamic therapy for the treatment of tracheobronchial papillomatosis: A multicenter experience.

OBJECTIVE: Recurrent respiratory papillomatosis (RRP) causes mucosal wart-like growths of the upper aerodigestive tract, which can undergo malignant transformation. These tumors are difficult to treat, often requiring repeated debridement, which can be associated with high morbidity. Photodynamic therapy (PDT) uses a photosensitizing medication and a topically applied light source to treat early stage endobronchial lung cancer. Most data on the use of PDT in RRP pertain to laryngeal disease. Our objective was to evaluate the effectiveness of PDT in treating RRP involving the lower respiratory tract. METHODS: We performed a retrospective multicenter review of adult patients who had a diagnosis of RRP involving the lower airways. We documented details of their disease, treatments, and outcomes. RESULTS: Eight patients underwent PDT for ten RRP lesions. Lesions were located in the trachea and more distal airways. Pathology showed malignant conversion to squamous cell carcinoma in half of the cases. All patient underwent debulking and multimodal treatment concurrently with PDT. Treatment was successful in seven patients with improvement in luminal size. Duration of disease-free recurrence ranged from 4 to 33 months. Five of eight patients have sustained ongoing treatment effect, ranging from 10 to 33 months. Most patient had improved quality of life (83 %) and a reduction in interventions (87 %) after PDT. Complications were minimal. CONCLUSION: PDT can be a safe and effective tool when treating RRP of the lower respiratory tract, including lesions with malignant transformation. A multimodal treatment approach is associated with improved outcomes. Further prospective studies are needed to fully determine its effectiveness.

Deep learning to convert unstructured CT pulmonary angiography reports into structured reports.

BACKGROUND: Structured reports have been shown to improve communication between radiologists and providers. However, some radiologists are concerned about resultant decreased workflow efficiency. We tested a machine learning-based algorithm designed to convert unstructured computed tomography pulmonary angiography (CTPA) reports into structured reports. METHODS: A self-supervised convolutional neural network-based algorithm was trained on a dataset of 475 manually structured CTPA reports. Labels for individual statements included "pulmonary arteries," "lungs and airways," "pleura," "mediastinum and lymph nodes," "cardiovascular," "soft tissues and bones," "upper abdomen," and "lines/tubes." The algorithm was applied to a test set of 400 unstructured CTPA reports, generating a predicted label for each statement, which was evaluated by two independent observers. Per-statement accuracy was calculated based on strict criteria (algorithm label counted as correct if the statement unequivocally contained content only related to that particular label) and a modified criteria, accounting for problematic statements, including typographical errors, statements that did not fit well into the classification scheme, statements containing content for multiple labels, etc. RESULTS: Of the 4,157 statements, 3,806 (91.6%) and 3,986 (95.9%) were correctly labeled by the algorithm using strict and modified criteria, respectively, while 274 (6.6%) were problematic for the manual observers to label, the majority of which (n = 173) were due to more than one section being included in one statement. CONCLUSION: This algorithm showed high accuracy in converting free-text findings into structured reports, which could improve communication between radiologists and clinicians without loss of productivity and provide more structured data for research/data mining applications.

Robot-assisted percutaneous placement of K-wires during minimally invasive interventions of the spine.

Purpose: To assess the accuracy and time requirements of image-guided percutaneous K-wire insertion in the spine using an advanced robot assistance device for needle guidance and to demonstrate a radiation-free workflow for the physician. Material and methods: A planning CT-scan was acquired of a cadaver specimen and analyzed using a 3D-interventional software integrated in the robotic device. The optimal needle path was simulated and the needle holder of the robot was used for guidance during K-wire insertion. Twenty-four K-wires were inserted percutaneously in a transpedicular approach in the following vertebrae: thoracic (T) 2, 7-12 and lumbar (L) 1-5. A post-procedural CT scan was performed to analyze the accuracy of the K-wire insertion. Results: All procedures were carried out without any perforation of the pedicle wall. The mean duration of planning the intervention path was 2:54 ± 2:22 min, mean positioning time was 2:04 ± 0:42 min and the mean time for K-wire insertion was 2:13 ± 0:54 min. In total, the average intervention time was 7:10 ± 3:06 min per pedicle. Compared to the planning, the K-wire position showed a mean deviation of 0.5 mm in the vertical-axis and 1.2 mm in the horizontal-axis. The average intervention path length was 8.1 cm. Conclusion: Our findings show a high accuracy in robot-assisted K-wire insertion during spinal interventions without any exposure of the operator to radiation.

Dual-energy CT of the heart current and future status.

Several applications utilizing dual-energy cardiac CT (DECT) have recently transitioned from the realm of research into clinical workflows. DECT acquisition techniques and subsequent post-processing can provide improved qualitative analysis, allow quantitative imaging, and have the potential to decrease requisite radiation and contrast material doses. Additionally, several experimental DECT techniques are pending further investigation and may improve the diagnostic accuracy of cardiac CT and/or provide evaluation of emerging imaging biomarkers in the future. This review article will summarize the major applications utilizing DECT in diagnosis of cardiovascular disease, including both the clinically used and investigational techniques examined to date.

Endoleaks after endovascular aortic aneurysm repair: Improved detection with noise-optimized virtual monoenergetic dual-energy CT.

PURPOSE: To assess image quality and diagnostic performance of a noise-optimized algorithm to reconstruct virtual monoenergetic images (VMI+) for the detection of endoleaks after endovascular abdominal aortic aneurysm repair (EVAR) using dual-energy CT angiography (DE-CTA). MATERIALS AND METHODS: Seventy-five patients (42 men; 66.2±11.7years) underwent DE-CTA following EVAR. Arterial phase images were acquired in dual-energy mode for the reconstruction of standard linearly-blended M_0.5, VMI+ and traditional monoenergetic images (VMI) at 40-100keV in 10-keV intervals. Contrast-to-noise ratios (CNR) were calculated for the area of leakage in patients with endoleaks. Diagnostic accuracy for endoleak detection was evaluated by three blinded radiologists using the objectively best series for each reconstruction technique. RESULTS: Thirty-four out of 75 patients showed endoleaks. Quantitative image parameters were highest at 40-keV VMI+ (CNR, 21.3±11.1), compared to M_0.5 (CNR, 10.9±5.5) and all VMI series that showed highest values at 70keV (CNR, 13.5±6.6; all P<0.001). ROC analysis for endoleak detection revealed an area under the curve (AUC) of 0.992 for 40-keV VMI+ series, which was significantly higher (P≤0.039) compared to 70-keV VMI (0.914) and M_0.5 series (0.916). CONCLUSIONS: Noise-optimized VMI+ series at 40keV improve diagnostic accuracy for the detection and rule-out of endoleaks after EVAR.

Cinematic Rendering in CT: A Novel, Lifelike 3D Visualization Technique.

OBJECTIVE: The purpose of this article is to present an overview of cinematic rendering, illustrating its potential advantages and applications. CONCLUSION: Volume-rendered reconstruction, obtaining 3D visualization from original CT datasets, is increasingly used by physicians and medical educators in various clinical and educational scenarios. Cinematic rendering is a novel 3D rendering algorithm that simulates the propagation and interaction of light rays as they pass through the volumetric data, showing a more photorealistic representation of 3D images than achieved with standard volume rendering.

Dynamic CT myocardial perfusion imaging.

Non-invasive cardiac imaging has rapidly evolved during the last decade due to advancements in CT based technologies. Coronary CT angiography has been shown to reliably assess coronary anatomy and detect high risk coronary artery disease. However, this technique is limited to anatomical assessment, thus non-invasive techniques for functional assessment of the heart are necessary. CT myocardial perfusion is a new CT based technique that provides functional assessment of the myocardium and allows for a comprehensive assessment of coronary artery disease with a single modality when combined with CTA. This review aims to discuss dynamic CT myocardial perfusion as a new technique in the assessment of CAD.

Myocardial perfusion imaging with dual energy CT.

Dual-energy CT (DECT) enables simultaneous use of two different tube voltages, thus different x-ray absorption characteristics are acquired in the same anatomic location with two different X-ray spectra. The various DECT techniques allow material decomposition and mapping of the iodine distribution within the myocardium. Static dual-energy myocardial perfusion imaging (sCTMPI) using pharmacological stress agents demonstrate myocardial ischemia by single snapshot images of myocardial iodine distribution. sCTMPI gives incremental values to coronary artery stenosis detected on coronary CT angiography (CCTA) by showing consequent reversible or fixed myocardial perfusion defects. The comprehensive acquisition of CCTA and sCTMPI offers extensive morphological and functional evaluation of coronary artery disease. Recent studies have revealed that dual-energy sCTMPI shows promising diagnostic accuracy for the detection of hemodynamically significant coronary artery disease compared to single-photon emission computed tomography, invasive coronary angiography, and cardiac MRI. The aim of this review is to present currently available DECT techniques for static myocardial perfusion imaging and recent clinical applications and ongoing investigations.

(18)F-DPA-714 PET Imaging for Detecting Neuroinflammation in Rats with Chronic Hepatic Encephalopathy.

Neuroinflammation is considered to be the pathogenesis of hepatic encephalopathy (HE), and imaging neuroinflammation is implicated in HE management. (11)C-PK11195, a typical translocator protein (TSPO) radiotracer, is used for imaging neuroinflammation. However, it has inherent limitations, such as short half-life and limited availability. The purpose of this study was to demonstrate the efficiency of new generation TSPO radiotracer, (18)F-DPA-714, in detecting and monitoring neuroinflammation of chronic HE. This study was divided into two parts. The first part compared (18)F-DPA-714 and (11)C-PK11195 radiotracers in ten HE induced rats [bile duct ligation (BDL) and fed hyperammonemic diet (HD)] and 6 control rats. The animal subjects underwent dynamic positron emission tomography (PET) during 2-day intervals. The (11)C-PK11195 PET study showed no differences in whole brain average percent injected dose per gram (%ID/g) values at all time points (all P>0.05), while the (18)F-DPA-714 PET study showed higher whole brain average %ID/g values in HE rats compared to control group rats at 900 s to 3300 s after injecting radiotracer (all P<0.05). The second part of the study evaluated the effectiveness of ibuprofen (IBU) treatment to chronic HE. Forty rats were classified into six groups, including Sham+normal saline (NS), Sham+IBU, BDL+NS, BDL+HD+NS, BDL+IBU, and BDL+HD+IBU groups. (18)F-DPA-714 PET was used to image neuroinflammation. Whole and regional brain average %ID/g values, neurological features, inflammatory factors and activated microglia showed better in the IBU groups than in the NS groups (all P<0.05) and no difference was seen in the Sham groups compared to IBU groups (all P>0.05). In conclusion, this study demonstrated that (18)F-DPA-714 is an ideal TPSO radiotracer for imaging neuroinflammation and monitoring anti-neuroinflammation treatment efficacy of chronic HE.