Use of an automatic recording system for CT doses: Evaluation of the impact of iterative reconstruction on radiation exposure in clinical practice

Evaluation of S100B blood level as a biomarker to avoid computed tomography in patients with mild head trauma under antithrombotic medication

PURPOSE

The goal of this prospective study was to analyze the potential of S100B protein as a negative predictive marker for intracranial hemorrhage (ICH) after mild head trauma (MHT) in patient under antithrombotic medication.

METHODS

Patients under antithrombotic medication who had MHT were consecutively included in this study. S100B blood levels were determined from samples drawn within 6hours after injury and were analyzed with the results of head CT performed within the 24hours after injury. Sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) of S100B levels for the detection of ICH, with a cut-off set at 0.105μg/L, were calculated.

RESULTS

A total of 308 patients (151 men and 157 women) with a mean age of 79.1±10.5years (SD) were included in the analysis. CT was positive for the presence of ICH in 33 patients (10.7%; 95% CI: 7.5-14.7%). In the study population, S100B showed a sensitivity of 84.8% (95%CI: 68.1-94.9%), a specificity of 30.2% (95% CI: 24.8-36.0%), a NPV of 94.3% (95% CI: 87.2-98.1%), and a PPV of 12.7% (95% CI: 8.6-17.9%) for the diagnosis of ICH.

CONCLUSION

The results of this study suggest that a S100B serum level<0.105μg/L has a high NPV for ICH after mild head trauma in patients under antithrombotic medication.

Feasibility of high-pitch dual-source low-dose chest CT: Reduction of radiation and cardiac artifacts

PURPOSE

To compare the radiation dose and image quality, focused mainly on cardiac pulsation artifact, between high-pitch low-dose chest computed tomography (HP-LDCT) and standard low-dose chest CT (LDCT).

PATIENTS AND METHODS

One hundred patients underwent HP-LDCT (50 patients) or LDCT (50 patients). Scan parameters were the same except for the pitch and gantry rotation time: 3.0 vs. 1.2 and 0.28s vs. 0.5s, respectively. Objective image noise at five regions and subjective image quality, such as noise, artifacts, cardiac pulsation artifacts, and overall diagnostic acceptability, were evaluated using a five-point scale. The significance level for all tests was set at P<0.05.

RESULTS

The dose-length products (DLPs) with HP-LDCT and LDCT were 90.2±4.3mGycm and 103.1±6.4mGycm, respectively (P<0.01). DLP of HP-LDCT showed a 13% reduction versus LDCT. Objective image noise was not significantly different. Cardiac pulsation artifacts showed a significant reduction on HP-LDCT (P<0.01). Other subjective image quality parameters of HP-LDCT were similar to those of LDCT. The overall diagnostic acceptability of HP-LDCT was better than that of LDCT (P<0.01).

CONCLUSIONS

HP-LDCT showed a 13% mean radiation dose reduction with no deterioration in image quality due to cardiac pulsation artifacts.

MDCT evaluation of nasopalatine canal morphometry and variations: An analysis of 100 patients

OBJECTIVE

The goal of this study was to investigate the possible variations in morphology of nasopalatine canal (NPC) morphometry depending on age, gender and absence of anterior incisors using multidetector row computed tomography (MDCT).

MATERIALS AND METHODS

A total of 100 patients (50 men, 50 women) with a mean age of 43.29±18.81 (SD) years (range: 18-90 years) who have undergone head MDTC were included into the study. Foramen nasalis diameter (P1), foramen incisivum diameter (P2), NPC length (P3), distance between buccal wall of incisive foramen and facial side of the buccal bone (P4), distances between buccal bone wall of NPC and facial side of buccal bone (P5), distance between mid-NPC buccal wall and facial side of buccal bone (P6), distance between buccal wall of NPC and the apex of anterior central incisors (P7) and NPC angle (P8) were measured. Formal variations in NPC were searched for. Differences in morphometric data were searched using Student t-test or Mann-Whitney test. Gender-based analysis of the variations was done with the χ² test. Pearson's test was used to search for correlation between morphometric data and age.

RESULTS

P1 was larger in men (3.72±1.41mm) than in women (3.07±1.34mm) (P<0.001). Similarly, P3 was larger in men (13.68±2.73mm) than in women (11.43±2.78mm) (P<0.001). No differences in the other NPC measurements (P2, P4, P5, P6, P7, P8) were found between men and women. Morphological variations in NPC (cylindrical, hourglass, banana shape, funnel shape, single canal, Y-type canal, parallel canal and others) were detected with frequencies ranging from 8 to 65.3%. A significant negative correlation was found between NCP measurements and patient age for P3 (r=-0.311; P=0.002), P4 (r=-0.267; P=0.007) and P8 (r=-0.318; P<0.001). New NPC variations, which were not reported before were found in 19% of our patients.

CONCLUSION

NPC shows myriad potential variations that have various prevalences. It is assumed that familiarity with these variations may help decrease the incidence of complications during facial or dental surgery.

Radiation dose and diagnostic accuracy of high-pitch dual-source coronary angiography in the evaluation of coronary artery stenoses

PURPOSE

"Flash Spiral" imaging is a new prospective ECG-triggered spiral scan mode that uses a very high-pitch for coronary computed tomography angiography (CTA). This enables complete image acquisition within one cardiac cycle with a very low radiation exposure. The aim of this study was to investigate the diagnostic accuracy, image quality, and effective radiation dose of prospectively ECG-triggered high-pitch spiral method (Flash spiral mode) of coronary CTA using dual-source technology for the evaluation of coronary artery stenoses.

MATERIAL AND METHODS

The study included 186 consecutive patients (115men, 71women; mean age: 53.37 years) who underwent coronary CTA. Coronary CTA was performed with a 128×2-slice dual-source CT (Somatom Definition Flash, Siemens, Germany) using a prospectively ECG-triggered high-pitch spiral mode. Patients were divided into three groups according to heart rate (≤65bpm, 66-75bpm, ≥76bpm) and body mass index (BMI) (20-24kg/m(2), 25-29kg/m(2), 30-34kg/m(2)) values. The correlation between heart rates, image quality and BMI values are investigated. A four-point scale (1=excellent, 4=poor/non-diagnostic) was used to rank the comparative image quality. Effective radiation doses were calculated. Also the correlation between radiation dose, sex and BMI values were investigated. In addition, diagnostic accuracy of CTA for detection of significant (≥50%) coronary artery stenoses was compared with invasive coronary angiography findings of 612vessel segments in 38patients. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy rate were calculated.

RESULTS

A total of 2976coronary artery segments were present. Of all coronary artery segments, 2381 (80%) had an image quality score of 1, and 1.5% segments were rated as "poor/non-diagnostic". When the correlation between heart rate and image quality is investigated, there was a significant difference between ≤65bpm and ≥76bpm groups. However, there was no significant difference between ≤65bpm and 66-75bpm groups. The mean effective dose was found as 1.3mSv (min: 0.5, max: 2.4mSv). The correlation between effective radiation dose and BMI was moderate. However, the correlation between gender and radiation dose was significant. Sensitivity, specificity, negative predictive value and accuracy of coronary CTA on a per-vessel segment were 90.1%, 97.4%, 98.6%, and 96.5%, respectively.

CONCLUSIONS

Prospectively ECG-triggered high-pitch spiral mode coronary CTA provides high image quality and diagnostic accuracy, with very low radiation dose for evaluation and exclusion of coronary artery stenoses.

Gastrointestinal stenting: Current status and imaging features

The use of stents in the gastrointestinal tract has been subjected to major changes. Initially, the use of stents was restricted to malignant strictures in patients with metastatic disease. But thanks to reduction of the morbidity and mortality rates, they are now used with curative intention and in patients with benign diseases after careful selection. However, for patients presenting with colon obstruction due to an advanced colon carcinoma, the mortality and morbidity are still high. The purpose of this review is to provide an overview of indications, techniques and further developments of the stents in the gastrointestinal tract and to highlight the predominant role of multidetector row computed tomography (MDCT) in the detection of potential complications.

Dose reduction with iterative reconstruction: Optimization of CT protocols in clinical practice

OBJECTIVES

To create an adaptable and global approach for optimizing MDCT protocols by evaluating the influence of acquisition parameters and Iterative Reconstruction (IR) on dose reduction and image quality.

MATERIALS AND METHODS

MDCT acquisitions were performed on quality image phantom by varying kVp, mAs, and pitch for the same collimation. The raw data were reconstructed by FBP and Sinogram Affirmed Iterative Reconstruction (SAFIRE) with different reconstruction kernel and thickness. A total of 4032 combinations of parameters were obtained. Indices of quality image (image noise, NCT, CNR, SNR, NPS and MTF) were analyzed. We developed a software in order to facilitate the optimization between dose reduction and image quality. Its outcomes were verified on an adult anthropomorphic phantom.

RESULTS

Dose reduction resulted in the increase of image noise and the decrease of SNR and CNR. The use of IR improved these indices for the same dose without affecting NCT and MTF. The image validation was performed by the anthropomorphic phantom. The software proposed combinations of parameters to reduce doses while keeping indices of the image quality adequate. We observed a CTDIvol reduction between -44% and -83% as compared to the French diagnostic reference levels (DRL) for different anatomical localization.

CONCLUSION

The software developed in this study may help radiologists in selecting adequate combinations of parameters that allows to obtain an appropriate image with dose reduction.