Does delayed phase imaging in CT angiography provide additional information in patients with suspected active bleeding?

PURPOSE: We hypothesize that delayed phase imaging does not provide additional diagnostic information in patients who undergo multi-phasic CTA for suspected active bleeding. METHODS: Data on patients who underwent multiphasic CTA (pre-contrast, arterial, porto-venous, and delayed phases) for suspected acute bleed were retrospectively collected between January 2019 and November 2021. CTA images were reviewed by a general radiologist, an interventional radiologist, and a body imaging radiologist independently. Each reader evaluated if delayed phase images provided additional information that would change the final impression of the CTA report. Additional information regarding bleeding location, time needed for delayed image acquisition, and radiation exposure were also obtained. RESULTS: A total of 104 patients with CTAs were analyzed with an average age of 58 years ± 22. Studies rated with absent additional findings on delayed images were 102 (98.1%) by the interventional radiologist, 101 (97.1%) by the body imaging radiologist, and 100 (96.1%) by the general radiologist with percent agreement of 96.15% (kappa 0.54, p < 0.001). All the findings were characterized as unlikely to be clinically significant. Mean time added to complete a delayed phase images was 3.61 ± 3.4 min. The average CT dose length product (DLP) for the total exam was 3621.78 ± 2129.57 mGy.cm with delayed acquisition adding a mean DLP of 847.75 ± 508.8 mGy.cm. CONCLUSION: Delayed phase imaging does not provide significant additional diagnostic information in evaluating patients with suspected active bleeding but is associated with increased examination time and radiation exposure.

Optimization of the "Perth CT" Protocol for Preoperative Planning and Postoperative Evaluation in Total Knee Arthroplasty.

Background and Objectives: Total knee arthroplasty (TKA) has become the treatment of choice for advanced osteoarthritis. The aim of this paper was to show the possibilities of optimizing the Perth CT protocol, which is highly effective for preoperative planning and postoperative assessment of alignment. Materials and Methods: The cross-sectional study comprised 16 patients for preoperative planning or postoperative evaluation of TKA. All patients were examined with the standard and optimized Perth CT protocol using advance techniques, including automatic exposure control (AEC), iterative image reconstruction (IR), as well as a single-energy projection-based metal artifact reduction algorithm for eliminating prosthesis artifacts. The effective radiation dose (E) was determined based on the dose report. Imaging quality is determined according to subjective and objective (values of signal to noise ratio (SdNR) and figure of merit (FOM)) criteria. Results: The effective radiation dose with the optimized protocol was significantly lower compared to the standard protocol (p < 0.001), while in patients with the knee prosthesis, E increased significantly less with the optimized protocol compared to the standard protocol. No significant difference was observed in the subjective evaluation of image quality between protocols (p > 0.05). Analyzing the objective criteria for image quality optimized protocols resulted in lower SdNR values and higher FOM values. No significant difference of image quality was determined using the SdNR and FOM as per the specified protocols and parts of extremities, and for the presence of prothesis. Conclusions: Retrospecting the ALARA ('As Low As Reasonably Achievable') principles, it is possible to optimize the Perth CT protocol by reducing the kV and mAs values and by changing the collimation and increasing the pitch factor. Advanced IR techniques were used in both protocols, and AEC was used in the optimized protocol. The effective dose of radiation can be reduced five times, and the image quality will be satisfactory.

Image quality of automatic coronary CT angiography reconstruction for patients with HR ≥ 75 bpm using an AI-assisted 16-cm z-coverage CT scanner.

BACKGROUND: Coronary CT angiography (CCTA) is a complicated CT exam in comparison to other CT protocols. Exam success highly depends on image assessment of experienced radiologist and the procedure is often time-consuming. This study aims to evaluate feasibility of automatic CCTA reconstruction in 0.25 s rotation time, 16 cm coverage CT scanner with best phase selection and AI-assisted motion correction. METHODS: CCTA exams of 90 patients with heart rates higher than 75 bpm were included in this study. Two image series were reconstructed-one at automatically selected phase and another with additional motion correction. All reconstructions were performed without manual interaction of radiologist. A four-point Likert scale rating system was used to evaluate the image quality of coronary artery segment by two experienced radiologists, according to the 18-segment model. Analysis was done on per-segment basis. RESULTS: Total 1194 out of the 1620 segments were identified for quality evaluation in 90 patients. After automatic best phase selection, 1172 segments (98.3%) were rated as having diagnostic image quality (scores 2-4) and the average score is 3.64 ± 0.55. When motion corrections were applied, diagnostic segment number increases to 1192 (99.8%) and the average score is 3.85 ± 0.37. CONCLUSIONS: With the help of 0.25 s rotation speed, 16-cm z-coverage and AI-assisted motion correction algorithm, CCTA exam reconstruction could be performed with minimum radiologist involvement and still meet image quality requirement.

Third-generation iterative reconstruction on a dual-source, high-pitch, low-dose chest CT protocol with tin filter for spectral shaping at 100 kV: a study on a small series of COVID-19 patients.

OBJECTIVES: To investigate the role of third-generation iterative reconstruction (ADMIRE) in dual-source, high-pitch chest CT protocol with spectral shaping at 100 kVp in Coronavirus disease 2019 (COVID-19). METHODS: Confirmed COVID-19 inpatients undergoing to unenhanced chest CT were scanned with a dual-energy acquisition (DECT, 90/150Sn kV) and a dual-source, high-pitch acquisition with tin-filtered 100 kVp (LDCT). On the DECT with ADMIRE 3 (DECT3) were evaluated the pulmonary findings and their extension (25-point score). Two radiologists in consensus evaluated with 5-point scales the overall image quality, the anatomical structures, and the elementary findings on LDCT reconstructed with filtered backprojection (LDCT0), with ADMIRE 3 (LDCT3) and 5 (LDCT5), and on DECT3. The signal-to-noise ratio (SNR), the body mass index, the exposure times, and the radiation doses were recorded. RESULTS: Seventy-five patients (57 M/18F; median age: 63 y.o.) were included, with median pulmonary extension of 13/25 points. The imaging findings were detected in proportion comparable to the available literature. The ADMIRE significantly improved the SNR in LDCT (p < 0.00001) with almost no significant differences in overweight patients. The LDCT had median effective dose of 0.39 mSv and acquisition time of 0.71 s with significantly less motion artifacts than DECT (p < 0.00001). The DECT3 and LDCT3 provided the best image quality and depiction of pulmonary anatomy and imaging findings, with significant differences among all the series (p < 0.00001). CONCLUSION: The LDCT with spectral shaping and ADMIRE3 provided acceptable image quality in the evaluation of patients with COVID-19, with significantly reduced radiation dose and motion artifacts.

Split-Bolus, Single-Acquisition, Dual-Phase Abdominopelvic CT Angiography for the Evaluation of Lung Transplant Candidates: Image Quality and Resource Utilization.

OBJECTIVE. The purpose of this study was to assess the image quality and resource utilization of single-injection, split-bolus, dual-enhancement abdominopelvic CT angiography (hereafter referred to as dual-enhancement CTA) performed for combined vascular and solid organ assessment compared with those of single-injection, single-enhancement abdominopelvic CT angiography (hereafter referred to as single-enhancement CTA) for vascular assessment in combination with additional examinations (CT, MRI, and US) performed to assess for malignancy in lung transplant candidates. MATERIALS AND METHODS. We retrospectively reviewed 100 patients who underwent abdominopelvic CTA examinations before lung transplant. Cohort A (n = 50) underwent dual-enhancement CTA and cohort B (n = 50) underwent single-enhancement CTA. Contrast opacification of the vasculature was assessed along the abdominal aorta through the right femoral artery. Solid organ enhancement was assessed in the right lobe of the liver and the right renal cortex. Measurements of mean radiation dose, contrast exposure, and cost of the studies (in U.S. dollars) were compared. RESULTS. Mean (± SD) vascular enhancement on dual-enhancement CTA and single-enhancement CTA was 334.2 ± 26.5 HU (coefficient of variation, 8.3%) and 340.0 ± 21.6 HU (coefficient of variation, 6.5%) (p = 0.23), respectively. For dual-enhancement CTA and single-enhancement CTA, mean liver enhancement was 125.8 ± 30.5 HU and 60.4 ± 6.9 HU (p < 0.01), respectively, whereas mean renal cortical enhancement was 260.3 ± 62.2 HU and 133.4 ± 38.6 HU (p < 0.01), respectively. The mean IV contrast volume was 150 mL for dual-enhancement CTA and 75 mL for single-enhancement CTA. Cohort A underwent six additional imaging studies (one of which was a CT colonography study with an effective dose of 19.0 mSv) at a total cost of $9840 per patient. Cohort B underwent 44 additional imaging studies (mean effective dose, 12.7 ± 6.5 mSv) at a total cost of $12,846 per patient (resulting in a 30.6% reduction in cost for dual-enhancement CTA studies; p < 0.0001). CONCLUSION. Dual-enhancement abdominopelvic CTA allows combined vascular and abdominopelvic solid organ assessment with improved image quality and a lower cost compared with traditional imaging pathways.

Synchronous tumours detected during cancer patient staging: prevalence and patterns of occurrence in multidetector computed tomography.

PURPOSE: The incidental detection of one or more additional primary tumours during computed tomography (CT) staging of a patient with known malignancy is rare but possible. This occurrence should be considered by the radiologist when a new lesion is detected, especially if the lesion location is atypical for metastases. The purpose of this report was to document the usefulness of total body CT scan to detect synchronous primary malignancies in cancer patients undergoing a staging workup. MATERIAL AND METHODS: This was done by reviewing the staging CT studies of the adult patients with a newly diagnosed cancer evaluated during a five-year period in a single cancer institute in order to identify any possible correlation, establishing which tumours are more frequently combined with a second tumour and which second tumours are more commonly present. RESULTS: Among the patients with a second tumour, the most frequent first primary tumours were melanoma (eight patients, 17.8%), lymphoma (seven patients, 15.6%), and prostate carcinoma (seven patients, 15.6%). The most frequent incidentally detected second tumours were hepatocellular carcinoma (nine patients, 20% of 45 incidental tumours), renal carcinoma (eight patients, 17.8%), lung carcinoma (seven patients, 15.6%), and bladder carcinoma (four patients, 8.9%). One patient had three primary tumours synchronously. CONCLUSIONS: We believe that the radiologist's knowledge of the prevalence and pattern of occurrence of these multiple primary malignancies represents added diagnostic value.

Can virtual monochromatic images from dual-energy CT replace low-kVp images for abdominal contrast-enhanced CT in small- and medium-sized patients?

OBJECTIVE: To investigate the image quality and radiation dose of dual-energy computed tomography (DECT) with automatic spectral imaging protocol selection (ASIS) compared with those of low-kVp CT in abdominal multiphase CT. METHODS: Four groups of 60 patients each underwent abdominal scans with low-kVp CT (A, 80 kVp/300 mg I/kg, body mass index [BMI] ≤ 23.9 kg/m2; C, 100 kVp/400 mg I/kg, BMI ranging from 24 to 28.9 kg/m2) or DECT with ASIS, and the 40- to 60-keV virtual monochromatic images (VMIs) generated (B and D) were matched by age, gender, BMI, cross-sectional area, and contrast agent dose; 9 patients were excluded due to technical failures. The CT number, image noise, contrast-to-noise ratio, and subjective image quality were compared between the matched protocols (A and B or C and D) on 1.25-mm reconstructed images. RESULTS: VMIs at approximately 55 keV and 62 keV had CT numbers and contrast similar to those of 80-kVp and 100-kVp CT images, respectively. Compared to matched low-kVp images, VMIs at 50 keV provided a higher CT number and image noise and a similar or higher contrast and overall image quality. The radiation dose for DECT was higher than that of 80-kVp CT (increased by 10%), but was similar to that of 100-kVp CT. CONCLUSION: Compared to matched low-kVp CT, VMIs at 50 keV in DECT with ASIS provided similar or higher overall image quality, with no or minimal dose penalty in small- and medium-sized patients. KEY POINTS: • Virtual monochromatic images at approximately 55 keV and 62 keV have CT numbers and contrast similar to those of 80-kVp and 100-kVp CT images, respectively, with a given noise index. • The radiation dose in dual-energy CT with automatic spectral imaging protocol selection was slightly higher than that of 80-kVp CT (increased by 10%) but was similar to that of 100-kVp CT. • Dual-energy CT may be able to replace l00-kVp CT for routine clinical abdominal contrast-enhanced CT scans.

The additional value of the arterial phase in the CT assessment of liver vascular injuries after high-energy blunt trauma.

PURPOSE: In the literature, no consensus exists about which CT protocol is to be adopted in patients who underwent high-energy blunt trauma. The aim of the study is to evaluate the additional value of the arterial phase in the CT assessment of vascular injuries of the liver. METHODS: Admission CT examinations for patients with traumatic injury of the liver due to high-energy blunt trauma, performed between 2011 and 2017 in two major trauma centres, were retrospectively reviewed. Images were analysed for presence or absence of liver parenchymal injury, intrahepatic contained vascular injuries and active bleeding in the arterial and portal venous phase of the CT study. RESULTS: Two hundred twelve patients have been identified. Parenchymal injuries were detected as isolated in 90.6% of cases, whereas they were associated with vascular injuries in 9.4% of cases: contained vascular injuries in 3.3% and active bleeding in 6.1%. Out of all parenchymal injuries detected on the CT portal venous phase, 90.5% were also detectable in the arterial phases (p < 0.0001). All of the contained vascular injuries were visible in the CT arterial phase, whereas they were detectable in 28.5% of cases also during the venous phase (p = 0.02). All 13 cases of active bleeding were detected on the CT venous phase, and 76.9% of these cases were also revealed in the arterial phase, thus confirming their arterial origin (p = 0.22). CONCLUSION: The addiction of the arterial phase to the venous phase in the CT assessment of patients who underwent high-energy blunt trauma allows an accurate identification and characterization of traumatic vascular injuries, so distinguishing between patients suitable for conservative management and those requiring interventional or surgical treatment.

The Current State of CT Dose Management Across Radiology: Well Intentioned but Not Universally Well Executed.

OBJECTIVE: Recent well-publicized sentinel events have resulted in an appropriately heightened awareness of CT dose. Concern also exists regarding the potential of CT dose increasing the risk of cancer. Several professional societies, governmental and accreditation agencies, and CT vendors have responded to these concerns with campaigns, mandatory standards, and software enhancements. The objective of this article is to review such CT dose management efforts. CONCLUSION: Although CT dose awareness campaigns, mandatory standards, and software enhancements are well intentioned, their implementation is often suboptimal.

A new low-dose multi-phase trauma CT protocol and its impact on diagnostic assessment and radiation dose in multi-trauma patients.

PURPOSE: Computed tomography (CT) examinations, often using high-radiation dosages, are increasingly used in the acute management of polytrauma patients. This study compares a low-dose polytrauma multi-phase whole-body CT (WBCT) protocol on a latest generation of 16-cm detector 258-slice multi-detector CT (MDCT) scanner with advanced dose reduction techniques to a single-phase polytrauma WBCT protocol on a 64-slice MDCT scanner. METHODS: Between March and September 2015, 109 polytrauma patients (group A) underwent acute WBCT with a low-dose multi-phase WBCT protocol on a 258-slice MDCT whereas 110 polytrauma patients (group B) underwent single-phase trauma CT on a 64-slice MDCT. The diagnostic accuracy to trauma-related injuries, radiation dose, quantitative and semiquantitative image quality parameters, subjective image quality scorings, and workflow time parameters were compared. RESULTS: In group A, statistically significantly more arterial injuries (p = 0.04) and arterial dissections (p = 0.002) were detected. In group A, the mean (±SD) dose length product value was 1681 ± 183 mGy*cm and markedly lower when compared to group B (p < 0.001). The SDs of the mean Houndsfield unit values of the brain, liver, and abdominal aorta were lower in group A (p < 0.001). Mean signal-to-noise ratios (SNRs) for the brain, liver, and abdominal aorta were significantly higher in group A (p < 0.001). Group A had significantly higher image quality scores for all analyzed anatomical locations (p < 0.02). However, the mean time from patient registration until completion of examination was significantly longer for group A (p < 0.001). CONCLUSIONS: The low-dose multi-phase CT protocol improves diagnostic accuracy and image quality at markedly reduced radiation. However, due to technical complexities and surplus electronic data provided by the newer low-dose technique, examination time increases, which reduces workflow in acute emergency situations.

Radiation Dose Reduction in Pediatric Body CT Using Iterative Reconstruction and a Novel Image-Based Denoising Method.

OBJECTIVE: The objective of this study was to evaluate the radiation dose reduction potential of a novel image-based denoising technique in pediatric abdominopelvic and chest CT examinations and compare it with a commercial iterative reconstruction method. MATERIALS AND METHODS: Data were retrospectively collected from 50 (25 abdominopelvic and 25 chest) clinically indicated pediatric CT examinations. For each examination, a validated noise-insertion tool was used to simulate half-dose data, which were reconstructed using filtered back-projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) methods. A newly developed denoising technique, adaptive nonlocal means (aNLM), was also applied. For each of the 50 patients, three pediatric radiologists evaluated four datasets: full dose plus FBP, half dose plus FBP, half dose plus SAFIRE, and half dose plus aNLM. For each examination, the order of preference for the four datasets was ranked. The organ-specific diagnosis and diagnostic confidence for five primary organs were recorded. RESULTS: The mean (± SD) volume CT dose index for the full-dose scan was 5.3 ± 2.1 mGy for abdominopelvic examinations and 2.4 ± 1.1 mGy for chest examinations. For abdominopelvic examinations, there was no statistically significant difference between the half dose plus aNLM dataset and the full dose plus FBP dataset (3.6 ± 1.0 vs 3.6 ± 0.9, respectively; p = 0.52), and aNLM performed better than SAFIRE. For chest examinations, there was no statistically significant difference between the half dose plus SAFIRE and the full dose plus FBP (4.1 ± 0.6 vs 4.2 ± 0.6, respectively; p = 0.67), and SAFIRE performed better than aNLM. For all organs, there was more than 85% agreement in organ-specific diagnosis among the three half-dose configurations and the full dose plus FBP configuration. CONCLUSION: Although a novel image-based denoising technique performed better than a commercial iterative reconstruction method in pediatric abdominopelvic CT examinations, it performed worse in pediatric chest CT examinations. A 50% dose reduction can be achieved while maintaining diagnostic quality.

A Holistic Approach to CT Protocol and Dose Management.

PURPOSE: Challenges from administrative support, scanners' heterogeneity, patient size variation, and protocol mapping hinder CT protocol and dose management. We present a holistic approach to overcome these challenges. METHODS: A dose tracking software was selected with two key requirements: intelligent protocol mapping and customizable dose threshold settings according to the patient size. A multifaceted workflow was carefully implemented. It included patient size-dependent dose thresholds for e-mail alerts, a base protocol archive on a website with a unified format using an in-house developed reformat software upon protocol export, prompt dose alert follow-up, and well-controlled protocol changes. The thresholds were iteratively updated following protocol changes or review of dose statistics. The program outcome was evaluated using 11 protocols from January 2020 to May 2023 (N = 148,678) in comparison to ACR's achievable dose (AD) and dose reference levels (DRLs). RESULTS: The 75th percentile dose data were lower than the ACR's DRL on average, ranging from -4.9% to -36%. The median doses were in a range of -23% to 19% on average in comparison with the ACR's AD. The median value from pulmonary embolism scans initially showed 36% higher than the AD but was gradually reduced to nearly 3% lower than the AD. The percentage of unjustified alerted cases decreased from 80% in first half year of 2020 to 17% in the first 5 months of 2023. CONCLUSIONS: The results showed that our holistic approach to protocol and dose management has been effective. The impact to practice has been prompt and sustainable.

Computed Tomography Angiography: Principles and Advances.

This review describes current state-of-the-art computed tomography technology required to address human-physiology-based challenges unique to angiographic imaging. Challenges are based on the need to image a bolus of contrast agent traversing inside rapidly moving structures. This article reviews the latest methods to optimize contrast timing and minimize motion.

Gunshot vaginal trauma.

Nonobstetric vaginal or vulva trauma is an extremely rare occurrence, with an incidence of < 0.2% of traumas. CT represents the gold standard in the diagnosis of gunshot lesions due to its ability to detect and stage injuries with very high sensitivity and specificity. A standardized protocol for penetrating trauma is still under debate for the use of intravenous contrast only or also rectal and oral contrast. Herein, we report a case of gunshot vaginal trauma in a 43-year-old patient presenting with vaginal bleeding. In our case, the protocol was "patient's tailored," the intravaginal selective use of air was administered due to symptoms (vaginal bleeding) and CT findings, this 2-step protocol increased diagnostic confidence and allow a correct and challenging diagnosis.

Interobserver Agreement of Post-operative Perth Computed Tomography Protocol Data in Total Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) has become the treatment of choice for advanced osteoarthritis. Identifying malalignment is central to improving TKA outcomes and providing optimal management of TKA patients with post-operative pain and dissatisfaction. Computed tomography (CT) imaging has become increasingly popular as a more precise way of analysing post-TKA component alignment and the Perth CT protocol remains the current predominant assessment tool. This study aimed to analyse and compare inter- and intra-observer agreement of a post-operative multi-parameter quantitative CT assessment (Perth CT protocol) in TKA patients. METHODS: Post-operative CT images of 27 patients who underwent TKA were analysed retrospectively. Images were analysed by an experienced radiographer and a final-year medical student at least two weeks apart. Measurements for nine angles were collected: modified hip-knee-ankle (mHKA) angle, lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA), femoral flexion and tibial slope, femoral rotation angle, femoral-tibial match rotational angle, tibial tubercle lateralisation distance, and Berger's tibial rotation. Intra-observer and inter-observer intraclass correlation coefficients (ICCs) were calculated. RESULTS: Inter-observer reliability for the measurements of all variables varied from poor to excellent (ICC: -0.003 to 0.981). Five out of the nine angles demonstrated good to excellent reliability. Inter-observer reliability was highest for mHKA in the coronal plane and the poorest for the tibial slope angle in the sagittal plane. The intra-observer reliability for both reviewers was excellent (0.999 vs. 0.989). CONCLUSION: This study demonstrates that the Perth CT protocol has excellent intra-observer reliability and good to excellent inter-observer reliability for five out of nine of the measured angles used to assess component alignment post-TKA, making it a useful tool for surgical outcome prediction and success.

Optimising CT-chest protocols and the added value of venous-phase contrast timing; Observational case-control.

INTRODUCTION: To optimize CT chest protocol by comparing venous contrast timing with arterial timing for contrast opacification in vessels, qualitative image quality and radiologists' satisfaction and diagnostic confidence in assessing for potential nodal, pleural and pulmonary disease in general oncology outpatients. METHOD: Matched case-control study performed following CT protocol update. 92 patients with a range of primary malignancies with 2 CT chests in a 2-year period, one with an arterial phase protocol and the second in the 60 second venous phase, were included. Contrast attenuation in aorta, pulmonary artery and liver were measured. Subjective measurements assessed perivenous artefact, confidence in nodal pleural and pulmonary assessment and presence of pulmonary emboli. Statistical analysis was performed using paired and unpaired t-tests. RESULTS: Venous-phase CT demonstrated more consistent enhancement of the vessels, with higher attenuation of the nodes, pulmonary and pleural lesions. There was a significant reduction in perivenous beam hardening artefact on venous-phase CT (P < 0.001). Diagnostic confidence was significantly higher for nodal assessment and pleural abnormality visibility (P < 0.001) and pleural assessment (P < 0.05). There was no significant difference in pulmonary mass visibility. There was adequate enhancement to diagnose significant pulmonary emboli (PE) with 4 incidental PEs detected on the venous phase, extending to segmental vessels. CONCLUSION: Venous-phase CT chest performs better than arterial-phase on all fronts, without compromising assessment of incidental pulmonary emboli. When intravenous contrast is indicated in a routine chest CT (excluding a CT-angiogram), the default timing should be a venous or 60s phase.

Tailored versus fixed scan delay in contrast-enhanced abdominal multi-detector CT: An intra-patient comparison of image quality.

PURPOSE: To perform anintra-patient comparison betweena single-pass protocol (SP) and a portal venous phase (PVP) by means ofboth quantitative and qualitative analysis of image quality. METHODS: Forty patients (31 M; 9F; aged 20-77 years; BMI 23 ± 4 Kg/m2) underwent both a SP and a PVP using a 64-rows multi-detector CT with a median interval time of 56 days (range5-903). All patients underwent i.v. bolus injection (2.0 cc/sec) of 1.7 cc/Kg of a non ionic iodinated contrast-media (370 mgI/ml) with scan delays of 67 ± 8 and 90 s for the SP and the PVP, respectively. Signal- (SNR) and contrast-to-noise ratios (CNR) were calculated for most visceral organs and for both abdominal aorta (AA) and main portal vein (MPV). For qualitative analysis, reproduction of abdominal viscera and vascular structures was blindly evaluated and inter-observer agreement calculated by the weighted Cohen k-analysis. RESULTS: Attenuation values (H.U.) of AA (232 ± 53vs180 ± 36) and MPV (215 ± 39vs187 ± 42) were significantly (p < 0.001) higher in the SP than in PVP, respectively. At qualitative analysis, reproduction of mostabdominal viscerawas also significantly sharper (p < 0.001) with the SP than the PVPwith inter-observer agreement scores (k)ranging from 0.60 to 0.88 for all but one imaging criteria. CONCLUSIONS: As the SP resulted in a significantly higher vascular enhancement and in a sharper reproduction of most abdominal viscera, it may be better suited than a PVP for the CT evaluation of non traumatic acute abdomen.

Body packing, body stuffing and body pushing: Characteristics and pitfalls on low-dose CT.

Because of availability and low radiation dose level, low dose computed tomography (CT) is now commonly used to identify illicit in corpore drug transportation. This review illustrates the most common CT findings of in corpore drug transportation and describes complications due to in corpore drug transportation, with a special emphasis on low dose CT. Major information such as number of packets, exact location and aspect of packets must be assessed. Radiologist must be aware of the imaging characteristics of "in corpore" illicit drug transportation, and should know situations that may alter drug smugglers management.

Impact of standardized computed tomographic angiography for minimally invasive mitral and tricuspid valve surgery.

BACKGROUND: Femoral cannulation for extracorporeal circulation (ECC) is a standard procedure for minimally invasive cardiac surgery (MICS) of the atrio-ventricular valves. Vascular pathologies may cause serious complications. Preoperative computed tomography-angiography (CT-A) of the aorta, axillary and iliac arteries was implemented at our department. METHODS: Between July 2017 and December 2018 all MICS were retrospectively reviewed (n = 143), and divided into 3 groups. RESULTS: In patients without CT (n = 45, 31.5%) ECC was applied via femoral arteries (91.1% right, 8.9% left). Vascular related complications (dissection, stroke, coronary and visceral ischemia, related in-hospital death) occurred in 3 patients (6.7%). In patients with non-contrast CT (n = 35, 24.5%) only femoral cannulation was applied (94.3% right) with complications in 4 patients (11.4%). CT-angiography (n = 63, 44.1%) identified 12 patients (19.0%) with vulnerable plaques, 7 patients (11.1%) with kinking of iliac vessels, 41 patients (65.1%) with multiple calcified plaques and 5 patients (7.9%) with small femoral artery diameter (d ≤ 6 mm). In 7 patients (11.1%) pathologic findings led to alternative cannulation via right axillary artery, additional 4 patients (6.3%) were cannulated via left femoral artery. Only 2 patients (3.2%) suffered from complications. CONCLUSIONS: CT-A identifies vascular pathologies otherwise undetectable in routine preoperative preparation. A standardized imaging protocol may help to customize the operative strategy.

CT protocol optimisation in PET/CT: a systematic review.

PURPOSE: Currently, no consistent guidelines for CT scans used within PET/CT examinations are available. This systematic review provides an up-to-date overview of studies to answer the following questions: What are the specific CT protocols used in PET/CT? What are the possible purposes of requiring a CT study within a PET/CT scan? Is the CT protocol obtained from a dosimetric optimisation study? MATERIALS AND METHOD: PubMed/MEDLINE, Cochrane Library, Embase and Scopus were systematically searched for relevant studies in accordance with the PRISMA statement. The literature search was conducted from January 2007 until June 2019. Data derived from studies were standardized in order to reduce possible biases, and they were divided into clinically homogeneous subgroups (adult, child or phantom). Subsequently, we divided the CT protocol intents into 3 types (anatomic localization only, attenuation correction only and diagnostic purpose). A narrative approach was used to summarise datasets and to investigate their heterogeneity (due to medical prescription methodology) and their combination in multiseries CT protocols. When weighted computed tomography dose index (CTDIw) was available, we calculated the volumetric computed tomography dose index (CTDIvol) using the pitch value to make the results uniform. Eventually, the correlation between protocol intents and CTDIvol values was obtained using a Kruskal-Wallis one-way ANOVA statistical test. RESULT: Starting from a total of 1440 retrieved records, twenty-four studies were eligible for inclusion in addition to two large multicentric works that we used to compare the results. We analyzed 87 CT protocols. There was a considerable range of variation in the acquisition parameters: tube current-time product revealed to have the most variable range, which was 10-300 mAs for adults and 10-80 mAs for paediatric patients. Seventy percent of datasets presented scans acquired with tube current modulation, 9% used fixed tube current and in 21% of them, this information was not available. Dependence between mean CTDIvol values and protocol intent was statistically significant (p = 0.002). As expected, in diagnostic protocols, there was a statistically significant difference between CTDIvol values of with and without contrast acquisitions (11.68 mGy vs 7.99 mGy, p = 0.009). In 13 out of 87 studies, the optimisation aim was not reported; in 2 papers, a clinical protocol was used; and in 11 works, a dose optimisation protocol was applied. CONCLUSIONS: According to this review, the dose optimisation in PET/CT exams depends heavily on the correct implementation of the CT protocol. In addition to this, considering the latest technology advances (i.e. iterative algorithms development), we suggest a periodic quality control audit to stay updated on new clinical utility modalities and to achieve a shared standardisation of clinical protocols. In conclusion, this study pointed out the necessity to better identify the specific CT protocol use within PET/CT scans, taking into account the continuous development of new technologies.