Evaluation of signal intensity changes in dentate nucleus and globus pallidus on magnetic resonance imaging after intrathecal gadolinium-based contrast agent administration.

PURPOSE: Gadolinium deposition has been reported in several normal anatomical structures in the brain after repeated administration of intravenous gadolinium-based contrast agents (GBCAs) used in magnetic resonance imaging (MRI). This study presents preliminary results to see if there is any gadolinium deposition in the dentate nucleus and globus pallidus after using intrathecal GBCAs. METHODS: Between November 2018 and November 2020, 29 patients who underwent intrathecal contrast-enhanced MR cisternography with the suspicion of rhinorrhea were included in this prospective study. In contrast-enhanced MR cisternography, gadoterate meglumine was administered by intrathecal injection at a dose of 1 ml. One month later, patients had a control MRI with 3D T1 SPACE fat-saturated (FS) and susceptibility weighted images (SWI) sequences. The ratio of dentate nucleus signal intensity to middle cerebellar peduncle signal intensity (DN/MCP ratio) and the ratio of globus pallidus signal intensity to thalamus signal intensity (GP/T ratio) were calculated using region of interest (ROI) on pre-contrast and control MRI sequences. RESULTS: There was no significant difference for DN/MCP ratio and GP/T ratio on 3D T1 SPACE FS and SWI sequences after intrathecal GBCAs administration compared to baseline MRI. CONCLUSION: Administration of intrathecal GBCAs did not cause a measurable change in the signal intensity of the dentate nucleus and globus pallidus after a single injection.

Sphenoid sinus in the Holstein cow: A sectional and 3D reconstructive anatomical study.

Cattle disorders affecting the sphenoid sinus are underreported, likely due to difficulties in imaging and lacking topographic knowledge. This study aimed to provide a detailed description of the normal anatomical and morphometric features of the cattle sphenoid sinus. Twelve healthy adult Holstein cow heads were used, and the sinus was examined using CT, anatomical sectioning and 3D modelling. The sinus was bilaterally detected in all animals but exhibited structural asymmetry and significant interindividual differences in morphological characteristics. Three parts of the sinus were defined, namely the rostral, median and alar parts, which conform to the morphological structure of the sphenoid bone. The rostral part was bilateral in shape and located on the orbit wall of the presphenoid bone in all animals. The median part, which pneumatized the body of the sphenoid bone, was observed bilaterally in seven animals, while the alar part, which pneumatized the wing of the sphenoid bone, was formed bilaterally in four animals. The sinus volume and surface area were 11 ± 8 cm3 and 49 ± 30 cm2 , respectively. These findings may aid in the diagnosis of cattle sphenoid sinus disorders and contribute to the knowledge of regional anatomy for radiologists and clinicians.

Texture analysis of multiparametric magnetic resonance imaging for differentiating clinically significant prostate cancer in the peripheral zone.

BACKGROUND: Texture analysis (TA) provides additional tissue heterogeneity data that may assist in differentiating peripheral zone(PZ) lesions in multiparametric magnetic resonance imaging (mpMRI). This study investigates the role of magnetic resonance imaging texture analysis (MRTA) in detecting clinically significant prostate cancer (csPCa) in the PZ. METHODS: This retrospective study included 80 consecutive patients who had an mpMRI and a prostate biopsy for suspected prostate cancer. Two radiologists in consensus interpreted mpMRI and performed texture analysis based on their histopathology. The first-, second-, and higher-order texture parameters were extracted from mpMRI and were compared between groups. Univariate and multivariate logistic regression analyses were performed using the texture parameters to determine the independent predictors of csPCa. Receiver operating characteristic (ROC) curve analysis was conducted to assess the diagnostic performance of the texture parameters. RESULTS: : In the periferal zone, 39 men had csPCa, while 41 had benign lesions or clinically insignificant prostate cancer (cisPCa). Themajority of texture parameters showed statistically significant differences between the groups. Univariate ROC analysis showed that the ADC mean and ADC median were the best variables in differentiating csPCa (p < 0.001). The first-order logistic regression model (mean + entropy) based on the ADC maps had a higher AUC value (0.996; 95% CI: 0.989-1) than other texture-based logistic regression models (p < 0.001). DISCUSSION: MRTA is useful in differentiating csPCa from other lesions in the PZ. Consequently, the first-order multivariate regressionmodel based on ADC maps had the highest diagnostic performance in differentiating csPCa.

Quantitative measurements and morphological evaluation of fetal cardiovascular structures with fetal cardiac MRI.

PURPOSE: Fetal cardiac magnetic resonance imaging (FCMR) can be used as an imaging modality in fetal cardiovascular evaluation as studied in recent years. We aimed to evaluate cardiovascular morphology using FCMR and to observe the development of cardiovascular structures according to gestational age (GA) in pregnant women. METHOD: In our prospective study, 120 pregnant women between 19 and 37 weeks of gestation in whom absence of cardiac anomaly could not be excluded by ultrasonography (US) or, who were referred to us for magnetic resonance imaging (MRI) for suspected non-cardiovascular system pathology, were included. According to the axis of the fetal heart, axial, coronal, and sagittal multiplanar steady-state free precession (SSFP) and 'real time' untriggered SSFP sequence, respectively, were obtained. The morphology of the cardiovascular structures and their relationships with each other were evaluated, and their sizes were measured. RESULTS: Seven cases (6.3%) contained motion artefacts that did not allow the assessment and measurement of cardiovascular morphology, and three (2.9%) cases with cardiac pathology in the analysed images were excluded from the study. The study included a total of 100 cases. Cardiac chamber diameter, heart diameter, heart length, heart area, thoracic diameter, and thoracic area were measured in all fetuses. The diameters of the aorta ascendens (Aa), aortic isthmus (Ai), aorta descendens (Ad), main pulmonary artery (MPA), ductus arteriosus (DA, superior vena cava (SVC), and inferior vena cava (IVC) were measured in all fetuses. The left pulmonary artery (LPA) was visualised in 89 patients (89%). The right PA (RPA) was visualised in 99 (99%) cases. Four pulmonary veins (PVs) were seen in 49 (49%) cases, three in 33 (33%), and two in 18 (18%). High correlation values were found for all diameter measurements performed with GW. CONCLUSION: In cases where US cannot achieve adequate image quality, FCMR can contribute to diagnosis. The very short acquisition time and parallel imaging technique with the SSFP sequence allow for adequate image quality without maternal or fetal sedation.

Calcified Fibrin Sheath Embolism of Bilateral Pulmonary Arteries: A Second Case of the Literature.

INTRODUCTION/BACKGROUND: Central venous catheters, which provide a unique convenience in the management of critical patients, have many advantages, as well as early and late complications. Early complications include pneumothorax, vascular perforation, hematoma formation, air embolism, or catheter malposition that may occur during or shortly after catheter insertion. Late complications include infection, venous stenosis, catheter thrombosis, and catheter tip migration. In the literature, embolization of a calcified fibrin sheath due to a central venous catheter to the pulmonary artery has been reported only in one case. CASE PRESENTATION: The purpose of this report is to present bilateral pulmonary artery embolism in a patient who presented with cough and chest pain caused by calcified fibrin sheath of the port catheter removed before that was used for regular chemotherapeutic infusions due to liposarcoma, as the second case in the literature with imaging findings. The patient underwent medical treatment, and as a result of the treatment, symptoms regressed. CONCLUSION: Central venous catheters have many complications, and although it is rare, pulmonary embolism is one of them. The embolism of a calcified sheath is even rare, but it is still possible. However, an embolism can cause significant morbidity and even mortality for a patient if it occurs. As physicians, we should be aware of this entity to diagnose.

CT and cross-sectional anatomy of the paranasal sinuses in the Holstein cow.

The structure of paranasal sinuses in cattle is difficult to understand due to its complexity, age-related changes, and insufficient published data. In this prospective, anatomic study, we described the anatomy of the paranasal sinuses in the Holstein cow using computed tomography (CT) and cross-sectional anatomic slices. Twelve healthy adult Holstein cow heads were used for this study. The heads were scanned using CT, and frozen anatomical sections were taken. The locations, borders, and relationships of the paranasal sinuses were defined on the anatomical sections and CT images. The paranasal sinuses on each side of the head consisted of conchal (dorsal, middle, and ventral), maxillary, lacrimal, palatine, frontal, sphenoid sinuses, and ethmoidal cells. The frontal sinus pneumatized all bones surrounding the cranial cavity, except for the ethmoidal and body of basisphenoid bones. The sphenoid and ventral conchal sinuses were the most asymmetrical, and the middle conchal sinus was the simplest. The ventral conchal sinus was detected in eleven animals, one of which was unilateral. This sinus communicated with the middle nasal meatus (13/21) and ventral nasal meatus (8/21). Findings can be used as background for interpreting CT studies of cattle with clinical signs of sinonasal region diseases. Future cross-sectional radiological and reconstructive anatomical studies and investigation of the postnatal development of related structures in cattle are needed.

Giant Vertebral Artery Aneurysm in Behçet's Disease: A Rare Case and Review of the Literature.

BACKGROUND: Behçet's disease is a chronic inflammatory disease that involves systemic organs and vascular structures. Arterial system involvement is rarer than the venous system, and it is one of the major causes of death. Vertebral artery (VA) involvement is rare and there are a limited number of reported cases in the literature. This report aimed to present the imaging findings of a case of Behçet's disease with a giant aneurysm originating from the right VA. CASE REPORT: A 35-year-old woman with a 10-year history of Behçet's disease applied to our center with complaints of pain on the right side of the neck. CT angiography showed a 7.5x6.5 cm sized saccular aneurysm in the superior of the right hemithorax adjacent to the mediastinum, with contrast filling the V1 segment of the VA. In our case, the VA aneurysm had no relation to the subclavian artery and showed filling from the contralateral VA. The described findings were demonstrated in Doppler examination, phase-contrast MRI, and conventional and CT angiography. CONCLUSION: Behçet's disease is a chronic inflammatory disease that can involve the arterial system. Although VA involvement has not been reported frequently, this vasculitic process may affect all arterial structures.

Can Dynamic Susceptibility Contrast Perfusion Imaging be Utilized to Detect Isocitrate Dehydrogenase Gene Mutation in Gliomas?

AIM: To explore the ability of dynamic susceptibility contrast perfusion imaging (DSC-PI) to detect isocitrate dehydrogenase (IDH) gene mutation in gliomas. MATERIAL AND METHODS: Preoperative DSC-PI data on histopathologically proven gliomas obtained between January 2015 and December 2019 were reviewed retrospectively. All magnetic resonance imaging (MRI) examinations were performed using a 1.5-T scanner. The maximum relative cerebral blood volume (rCBVmax), percentage signal recovery (PSR), and normalized PSR of tumor cores were calculated. Differences in these values between IDH-mutant and wild-type gliomas were compared, and receiver operating characteristic curves were generated. RESULTS: The patients (32 females, 47 males) were aged 21-76 years (mean 50.7 ± 15 years). The rCBVmax and all PSR values differed significantly between patients with IDH-mutant and those with wild-type tumors (p < 0.01 for all comparisons). CONCLUSION: The rCBVmax and PSR values obtained by DSC-PI may facilitate noninvasive detection of the IDH mutation status of gliomas. PSR provided more reliable values for differentiation of IDH-mutant gliomas from wild-type gliomas.

Comparison of the Effectiveness of Shear Wave Elastography and Superb Microvascular Imaging in the Evaluation of Breast Masses.

ABSTRACT: This study aims to determine the diagnostic performance of superb microvascular imaging (SMI) and shear wave elastography methods in evaluating breast lesions. We will also compare the effectiveness of the stiffness, velocity, and vascular index (VI) parameters in distinguishing malignancy.From January to June 2019, 121 patients with 121 solid breast masses (category 4 and 5 lesions according to the Breast Imaging-Reporting and Data System) detected during the routine grayscale sonographic examination were included in the study. Stiffness and velocity values were obtained using shear wave elastography for all lesions, and VI was obtained using SMI. The receiver operating characteristic curves were obtained to set the best cutoff values for the stiffness, velocity, and VI to differentiate patients with malignant breast lesions.All 121 lesions were pathologically verified by US-guided core needle biopsy. Forty-seven (38.9%) of the lesions were malignant, and 74 (61.1%) were benign. Median stiffness, velocity, and VI values were significantly lower in benign masses compared with malignant masses (P < 0.001). The optimum cutoff values for the stiffness, velocity, and VI were determined to be 58.3 kPa, 4.5 m/s, and 1.1%, respectively. The areas under the curves were 0.897 for stiffness, 0.884 for velocity, and 0.687 for VI.Shear wave elastography and SMI are noninvasive methods that may be used to evaluate breast masses. Although both methods' quantitative data are beneficial in differentiating malignant from benign masses, stiffness is the best parameter to be used.

Diagnostic performance of Radiological Society of North America structured reporting language for chest computed tomography findings in patients with COVID-19.

PURPOSE: To evaluate the diagnostic performance of the RSNA structured reporting language for chest CT findings in patients with COVID-19. MATERIAL AND METHODS: Patients with suspected COVID-19 who underwent chest CT and RT-PCR tests were enrolled consecutively in this retrospective study, regardless of symptoms. Imaging findings were categorized as "typical", "indeterminate", "atypical", or "negative" according to RSNA reporting language and compared to RT-PCR. "Single, round GGO" and "single, peripheral GGO," do not fit the reporting language, were also analyzed as "indeterminate" patterns. RESULTS: Of the 1186 patients included in the analysis, the diagnosis of COVID-19 was confirmed in 388 patients. Of the 388 patients, CT findings were categorized as "typical" in 248, "indeterminate" in 77, and "negative" in 63. The sensitivity, specificity, and accuracy of "typical" findings were 63.9, 99.0, and 87.5% for COVID-19, respectively. In addition to the "typical" findings, the highest diagnostic accuracy of 92.2% was achieved when the "single, peripheral GGO" and "single, round GGO" were considered to be CT-positive. CONCLUSION: The RSNA reporting language has significant diagnostic performance for identifying COVID-19 pneumonia. CT findings that do not exactly fit the RSNA reporting language, such as "single, round GGO" and "single, peripheral GGO" improve diagnostic performance.

Evaluation of parenchymal vascularity of the thyroid gland with vascularization index by color superb microvascular imaging in patients with Graves' disease.

AIM OF THE STUDY: To determine the parenchymal vascularity of the thyroid gland with color superb microvascular imaging in patients with Graves' disease, and compare the vascularization index values with healthy subjects. MATERIALS AND METHODS: The thyroid glands of 37 patients whose laboratory and clinical findings were consistent with Graves' disease, and 40 asymptomatic subjects with normal laboratory values, were examined using color superb microvascular imaging. Measurements of the vascularization index were performed with a free region of interest which was drawn along the outer margin of the gland on the color superb microvascular imaging mode. The vascularization index values obtained in the Graves' disease and control groups were compared. A correlation analysis was performed between the vascularization index values and laboratory and grayscale US parameters. RESULTS: The median vascularization index value of the thyroid parenchyma in patients with Graves' disease was significantly higher than in the asymptomatic group [median (min-max); 12 (2.3-32.1) vs 5.04 (1.1-10.8), p <0.001]. When the cutoff value of the vascularization index is determined as 6.3, Graves' disease can be diagnosed with 83.8% sensitivity and 70% specificity. CONCLUSIONS: The vascularization index obtained with color superb microvascular imaging can be a quantitative indicator of parenchymal vascularity in the diagnosis of Graves' disease, and serve as a supportive tool.

Chest CT findings in RT-PCR positive asymptomatic COVID-19 patients.

PURPOSE: To investigate chest computed tomography (CT) findings in asymptomatic patients tested positive for coronavirus disease (COVID-19) by reverse transcription-polymerase chain reaction (RT-PCR). MATERIAL AND METHODS: The chest CT images of 64 patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who were RT-PCR test-positive but asymptomatic were retrospectively evaluated for the appearance and distribution of abnormal parenchymal findings. RESULTS: Of the 64 patients (mean age 59.4 ± 12; range 23-85), 42 (65%) were female, and 22 (35%) were male, and 16 (25%) of the patients had no abnormal findings on chest CT. Of the remaining 48 patients, lung involvement was bilateral in 32 (67%). Right upper lobe in 26 (54%), right middle lobe in 20 (42%), right lower lobe in 38 (79%), left upper lobe in 27 (56%), and left lower lobe were affected in 34 (71%) patients. The mean number of opacities detected in patients was 7.5 ± 5.7. The opacities were located only peripherally/subpleural in 22 (46%), only centrally/peribronchovascular in 5 (10%), and mixed in 21 (44%) patients. The frequency of pure ground glass opacities (GGO) was 63% GGO with a crazy-paving pattern or consolidation was 33%. Pure consolidation was detected in only two (4%) patients. Parenchymal opacities were only round in 27 (56%), only geographic demarcated in 3 (6%), only patchy in 2 (4%), and mixed in 16 (33%) patients. CONCLUSION: Chest CT was normal in only one-quarter of the asymptomatic patients. CT findings in asymptomatic COVID-19 patients were often peripherally located, mostly round-shaped GGO.

Evaluation of systemic involvement of Coronavirus disease 2019 through spleen; size and texture analysis

Background/aim: To investigate the changes in the spleen size, parenchymal heterogeneity, and computed tomography (CT) texture analysis features of patients diagnosed with Coronavirus disease 2019 (COVID-19) Materials and methods: The size and parenchymal structure of the spleen in 91 patients who underwent thoracic CT examination due to COVID-19 were evaluated. For the evaluation of parenchymal heterogeneity, CT texture analysis was performed using dedicated software (Olea Medical, France). The texture analysis of each case consisted of 15 first-order intensity-based features, 17 gray level co- occurrence matrix-based features, and 9 gray level run length matrix-based features. Results: A total of 91 patients (45 males, 46 females) with a mean age of 54.31 ± 16.33 years (range: 18­81) were included in the study. A statistically significant decrease in spleen size was seen in the follow-up CT examinations (p < 0.001) whereas no statistically significant difference was found between the Hounsfield unit (HU) values. The radiomics consisted of first-order intensity-based features such as 90th percentile, maximum, interquartile range, range, mean absolute deviation, standard deviation, and variance, all of which showed statistically significant differences (p-values: < 0.001, < 0.001, 0.001, 0.003, 0.001, 0.001, and 0.004, respectively). "Correlation" as a gray level co-occurrence matrix-based feature and "gray level nonuniformity" as a gray level run length matrix-based feature showed statistically differences (p-values: 0.033 and < 0.001, respectively). Conclusions: Although COVID-19 manifests with lung involvement in the early stage, it can also cause systemic involvement, and the spleen may be one of its target organs. A decrease in the spleen size and parenchymal microstructure changes can be observed in the short follow-up time. It is hoped that the changes in the parenchymal microstructure will be demonstrated by a noninvasive method: texture analysis.

Precise discrimination between meningiomas and schwannomas using time-to-signal intensity curves and percentage signal recoveries obtained from dynamic susceptibility perfusion imaging.

BACKGROUND AND PURPOSE: Meningiomas and schwannomas are common extra-axial brain tumors. Discrimination is challenging in some locations when characteristic imaging features are absent. This study investigated the accuracy of percentage signal recoveries obtained from dynamic susceptibility contrast perfusion imaging (DSC-PI) in discriminating meningiomas and schwannomas. MATERIAL AND METHODS: Retrospective database research was conducted. Sixty nine meningioma and 15 schwannoma having DSC-PI between January 2016 and February 2020 were included. Time to signal intensity curves (TSIC) were analyzed and grouped as T1-dominant leakage, T2*-dominant leakage and return to baseline. Relative cerebral blood volume (rCBV), relative mean transit time (rMTT), percentage signal recovery 1 (PSR 1) and PSR 2 values were calculated. The differences between the groups were investigated. Receiver operating characteristic curves were operated. RESULTS: rCBV, rMTT, PSR 1 and PSR 2 values were statistically different between meningiomas and schwannomas. PSR 2 provided the best discrimination. With the cut off value of 1.08 for PSR 2, meningiomas and schwannomas were differentiated with 95.7% sensitivity and 93.3% specificity. TSICs were also different between two groups. Most of meningiomas showed T2*-dominant leakage (78.2%), whereas most of shwannomas showed T1-dominant leakage (93.3%). CONCLUSION: DSC-PI is a useful imaging tool for non-invasive discrimination of meningiomas and schwannomas. Particularly, percentage signal recoveries discriminates meningiomas and schwannomas with high sensitivity and specificity.

Evaluation of the Stiffness of Thyroid Parenchyma With Shear Wave Elastography Using a Free-Region of Interest Technique in Graves Disease.

OBJECTIVES: The first aim was to evaluate the stiffness of thyroid parenchyma with shear wave elastography (SWE) in patients with Graves disease (GD) and compare the elastographic values with those of asymptomatic volunteers. The second aim was to evaluate whether there was a correlation between SWE values and grayscale ultrasound (US) and laboratory parameters. METHODS: In this prospective study, the thyroid gland parenchyma of 50 patients whose clinical and laboratory findings were indicative for GD and 54 asymptomatic participants with normal laboratory values was examined by SWE. Grayscale US images of the thyroid and submandibular gland were recorded. The volume of the thyroid gland was measured. Elastographic measurements were performed with a free region of interest. The quantitative SWE values (meters per second and kilopascals) of the patient and control groups were compared. A correlation analysis between the SWE values and grayscale US and laboratory parameters was performed. RESULTS: The median (range) SWE values of the thyroid gland in patients with GD were significantly higher than those of the control group [17.34 (12.58-56.15) versus 12.05 (7.72-23.67) kPa and 2.28 (1.83-4.12) versus 1.92 (1.55-2.61) m/s; P < .001 for both comparisons]. When 14.5 kPa or 2.115 m/s was designated as the cutoff value, GD could be diagnosed with a high sensitivity and specificity. We showed a negative weak correlation between the SWE values and parenchymal echogenicity in the GD group. CONCLUSIONS: Shear wave elastography can be used as an effective imaging method with high sensitivity and specificity rates in the diagnosis of GD.

Evaluation of benign parotid gland tumors with superb microvascular imaging and shear wave elastography.

Aim of the study: This study aimed to examine the role of superb microvascular imaging and shear wave elastography for the pre-surgical evaluation of common parotid tumors. Material and methods: This single-center prospective study included 37 patients with parotid gland lesions. After institutional review board approval, grayscale, shear wave elastography and superb microvascular imaging ultrasound examinations were performed prior to biopsy or operation. The diagnosis of the lesions was based on cytological/pathological evaluation after the ultrasound examinations. Pleomorphic adenomas and Warthin tumors were compared using the Mann-Whitney U test. A receiver operating characteristic curve analysis was performed to obtain a cut-off value. A multivariate regression analysis was carried out. Results: The mean age of the patients (11 female, 26 male) was 48.2 ± 18. The shear wave elastography parameters of the lesions were not significantly different between pleomorphic adenomas and Warthin tumors, while the vascular index obtained by using superb microvascular imaging was significantly different (p = 0.012). The mean vascular index was 2.9 ± 3.1 in pleomorphic adenomas, and 9.5 ± 9.5 in Warthin tumors. A cut-off value of 4.05 for the vascular index discriminated pleomorphic adenoma and Warthin tumors with 68% sensitivity and 72% specificity (the area under the curve was 0.768). Conclusion: Superb microvascular imaging is a novel ultrasound imaging technique which is useful for the discrimination of pleomorphic adenomas and Warthin tumors.

The effect of pectus excavatum deformity on lung volume: fact or myth?

BACKGROUND AND PURPOSE: Most of the previous studies evaluating lung volume of pectus excavatum (PE) patients were based on spirometric measurements. We aimed to calculate lung volume of patients with PE and compare them with lung volume of patients without chest wall deformity using CT volumetry. METHODS: After institutional review board approval, preoperative chest CT of PE patients who underwent minimal invasive procedure between January 2012 and February 2018, were evaluated retrospectively. As a control group, age and sex matched patients who underwent chest CT scan in the same period were enrolled. Total, right and left lung volumes were calculated using an automated software. Haller indexes were measured for both groups. Lung volumes and Haller indexes compared between the two groups. We also compared left and right lung volumes in both groups. We evaluated whether there is a correlation across the Haller index and total lung volume. RESULTS: Total, right and left lung volumes were not statistically different between the two groups. While left lung volumes were significantly smaller in PE group (p = 0.041), there was no significant difference between the left and right lung volume in the control group (p = 0.12). Haller index and total lung volume showed no significant correlation between patients with the same age and gender (p = 0.14, R = -0.3). CONCLUSIONS: PE deformity does not reduce lung volume when compared to age and sex matched control group. Quantitative CT volumetric evaluation of lung gives valuable data about lung volume.

A new technique for the diagnosis of acute appendicitis: abdominal CT with compression to the right lower quadrant.

OBJECTIVE: To determine the diagnostic accuracy of abdominal CT with compression to the right lower quadrant (RLQ) in adults with acute appendicitis. METHODS: 168 patients (age range, 18-78 years) were included who underwent contrast-enhanced CT for suspected appendicitis performed either using compression to the RLQ (n = 71) or a standard protocol (n = 97). Outer diameter of the appendix, appendiceal wall thickening, luminal content and associated findings were evaluated in each patient. Kruskal-Wallis, Fisher's and Pearson's chi-squared tests were used for statistical analysis. RESULTS: There was no significant difference in the mean outer diameter (MOD) between compression CT scans (10.6 ± 1.9 mm) and standard protocol (11.2 ± 2.3 mm) in patients with acute appendicitis (P = 1). MOD was significantly lower in the compression group (5.2 ± 0.8 mm) compared to the standard protocol (6.5 ± 1.1 mm) (P < 0.01) in patients without appendicitis. A cut-off value of 6.75 mm for the outer diameter of the appendix was found to be 100% sensitive in the diagnosis of acute appendicitis for both groups. The specificity was higher for compression CT technique (67.7 vs. 94.9%). CONCLUSION: Normal appendix diameter was significantly smaller in the compression-CT group compared to standard-CT group, increasing diagnostic accuracy of abdominal compression CT. KEY POINTS: • Normal appendix diameter is significantly smaller in compression CT. • Compression could force contrast material to flow through the appendiceal lumen. • Compression CT may be a CT counterpart of graded compression US.

Comparison of image quality and radiation dose between prospectively ECG-triggered and retrospectively ECG-gated CT angiography: Establishing heart rate cut-off values in first-generation dual-source CT.

OBJECTIVE: To evaluate radiation dose and image quality of prospectively electrocardiography (ECG)-triggered and retrospectively ECG-gated coronary computed tomography (CT) angiography and to establish cut-off values of heart rates (HRs) for each technique in first-generation dual-source CT. METHODS: A total of 200 consecutive patients with suspected coronary artery disease were accepted into the study. Patients were selected randomly for each technique (prospective triggering group n=99, mean age 55.85±10.74 and retrospective gating group n=101, mean age 53.38±11.58). Two independent radiologists scored coronary artery segments for image quality using a 5-point scale. Also, attenuation values of each coronary artery segment and dose-length product values were measured. For each technique, cut-off HR values were determined for the best image quality. RESULTS: Mean image quality scores and attenuation values were found to be higher in the prospective triggering group (p<0.05). Mean radiation dose was 73% lower for the prospective triggering group (p<0.01). The cut-off HR values for good image quality scores were ≤67 beats per minute (bpm) and ≤80 bpm for the prospective triggering and retrospective gating groups, respectively (p<0.05). Increased HR (≥68 and ≥81 bpm, respectively) had negative effects on image quality (p<0.05). CONCLUSION: The prospective ECG triggering technique has better image quality scores than retrospective ECG gating, particularly in patients who have an HR of less than 68 bpm. Also, a 73% radiation dose reduction can be achieved with prospective ECG triggering. In patients with higher heart rates, retrospective ECG gating is recommended.