CT Protocol Research Articles

High Diagnostic Accuracy of Arterial Phase CT in Differentiating Pheochromocytoma in Good/Poor Washout Adrenal Masses

Abstract Introduction Differentiating pheochromocytomas from other adrenal masses based on CT characteristics remains challenging, particularly in lipid-poor lesions with variable washout patterns. This study evaluated CT features for distinguishing pheochromocytomas in good and poor washout sub-cohorts. Methods We prospectively analyzed 72 patients with unilateral lipid-poor adrenal masses. CT protocol included basal, bolus-tracked arterial, early venous (45 seconds post-arterial), and delayed (15 minutes post-arterial) phases. Masses were categorized into good and poor washout groups. Histopathology provided the final diagnosis. CT characteristics and calculated indices were compared between pheochromocytomas and other masses in each washout category. Results The cohort included pheochromocytomas (n=35), adrenocortical carcinoma (ACC, n=15), lipid-poor adenomas (n=13), and metastatic infiltration/infection (n=9). In the good washout group, pheochromocytomas (n=15) showed larger diameters (6.00 vs. 3.45 cm, p=0.001), higher necrosis frequency (73.3% vs. 30%, p=0.049), and greater arterial attenuation (173.2 vs. 74.5 HU, p<0.001) compared to adenomas (n=9). Arterial attenuation provided a high discriminatory value (AUC: 0.967), with 100% sensitivity at 87.6 HU and 100% specificity at 139.9 HU. In the poor washout group, pheochromocytomas (n=20) exhibited higher arterial attenuation (99.2 vs. 59.2 HU, p<0.001; AUC: 0.844) compared to ACC (n=14), metastatic infiltration (n=9), and adenomas (n=4), with 85% sensitivity and 78% specificity at 73.3 HU. Normetanephrine-secreting/non-secretory pheochromocytomas showed higher arterial enhancement than metanephrine-secreting ones (132.0 vs. 90.5 HU, p=0.020) within the poor washout group. Conclusion Arterial phase attenuation on CT has good diagnostic accuracy for differentiating pheochromocytomas from other adrenal masses in both good and poor washout categories, potentially guiding hormonal workup.

Evaluating the Efficacy of Deep Learning Reconstruction in Reducing Radiation Dose for Computer-Aided Volumetry for Liver Tumor: A Phantom Study.

The purpose of this study was to compare radiation dose reduction capability for accurate liver tumor measurements of a computer-aided volumetry (CADv) software for filtered back projection (FBP), hybrid-type iterative reconstruction (IR), mode-based iterative reconstruction (MBIR), and deep learning reconstruction (DLR) at a phantom study. A commercially available anthropomorphic abdominal phantom was scanned five times with a 320-detector row CT at 600 mA, 400 mA, 200 mA, and 100 mA and reconstructed by four methods. Signal-to-noise ratios (SNRs) of all lesions within the arterial and portal-venous phase inserts were calculated, and SNR of the lesion phantom was compared with that of all reconstruction methods by means of Tukey's honestly significant difference (HSD) test. Then, tumor volume (V) of each nodule was automatically measured using commercially available CADv software. To compare dose reduction capability for each reconstruction method at both phases, mean differences between measured V and standard references were compared by Tukey's honestly significant difference test among the four different reconstruction methods on CT obtained at each of the four tube currents. With each of the tube currents, SNRs for MBIR and DLR were significantly higher than those for FBP and hybrid-type IR (p < 0.05). At the arterial phase, the mean difference in V for the CT protocol obtained at 600 or 100 mA and reconstructed with DLR was significantly smaller than that for others (p < 0.05). At the portal-venous phase, the mean differences in V for the CT protocol obtained at 100 mA and reconstructed with hybrid-type IR, MBIR, and DLR were significantly smaller than that for FBP (p < 0.05). Findings of our phantom study show that reconstruction method had influence on CADv merits for abdominal CT with not only standard but also reduced dose examinations and that DLR can potentially yield better image quality and CADv measurements than FBP, hybrid-type IR, or MBIR in this setting.

A simulation framework for preclinical proton irradiation workflow

Objective.The integration of proton beamlines with x-ray imaging/irradiation platforms has opened up possibilities for image-guided Bragg peak irradiations in small animals. Such irradiations allow selective targeting of normal tissue substructures and tumours. However, their small size and location pose challenges in designing experiments. This work presents a simulation framework useful for optimizing beamlines, imaging protocols, and design of animal experiments. The usage of the framework is demonstrated, mainly focusing on the imaging part.Approach.The fastCAT toolkit was modified with Monte Carlo (MC)-calculated primary and scatter data of a small animal imager for the simulation of micro-CT scans. The simulated CT of a mini-calibration phantom from fastCAT was validated against a full MC TOPAS CT simulation. A realistic beam model of a preclinical proton facility was obtained from beam transport simulations to create irradiation plans in matRad. Simulated CT images of a digital mouse phantom were generated using single-energy CT (SECT) and dual-energy CT (DECT) protocols and their accuracy in proton stopping power ratio (SPR) estimation and their impact on calculated proton dose distributions in a mouse were evaluated.Main results.The CT numbers from fastCAT agree within 11 HU with TOPAS except for materials at the centre of the phantom. Discrepancies for central inserts are caused by beam hardening issues. The root mean square deviation in the SPR for the best SECT (90 kV/Cu) and DECT (50 kV/Al-90 kV/Al) protocols are 3.7% and 1.0%, respectively. Dose distributions calculated for SECT and DECT datasets revealed range shifts <0.1 mm, gamma pass rates (3%/0.1 mm) greater than 99%, and no substantial dosimetric differences for all structures. The outcomes suggest that SECT is sufficient for proton treatment planning in animals.Significance.The framework is a useful tool for the development of an optimized experimental configuration without using animals and beam time.

Intra-arterial contrast administration: a confounding appearance on stroke CT imaging.

A female patient in her 70s presented with mild slurred speech. Clinical assessment revealed only minor dysarthria. A stroke protocol CT study was performed comprising a non-contrast CT head, CT angiogram (CTA) and CT perfusion (CTP) imaging. Despite a normal non-contrast CT head, CTP imaging demonstrated a large left anterior circulation territory abnormality compatible with core infarct. The CTA displayed absent left middle cerebral artery opacification and an abnormal pattern of thalamic and posterior fossa structure enhancement. Following a neuroradiology review, it was identified that the contrast bolus had been administered into the right brachial artery causing direct arterial opacification of the right vertebral/carotid arteries and their distal branches. No contrast was present in the left carotids or distal left intracranial anterior circulation giving the false impression of a large vessel occlusion. The patient was subsequently discharged without receiving inappropriate reperfusion therapy. This case highlights the role of technical factors influencing CT interpretation, particularly when performed by artificial intelligence/automated analysis.

An update on pancreatic cancer imaging, staging and use of the PACT-UK radiology template pre- and post-neoadjuvant treatment.

Pancreatic ductal adenocarcinoma continues to have a poor prognosis, although recent advances in neoadjuvant treatments have provided some hope. Imaging assessment of suspected tumours can be challenging and requires a specific approach, with pancreas protocol CT being the primary imaging modality for staging with other modalities used as problem-solving tools to facilitate appropriate management. Imaging assessment post neoadjuvant treatment can be particularly difficult due to a current lack of robust radiological criteria to predict response and differentiate treatment induced fibrosis/inflammation from residual tumour. This review aims to provide an update of pancreatic ductal adenocarcinoma with particular focus on three points: tumour staging pre- and post-neoadjuvant treatment including vascular assessment, structured reporting with introduction of the PACT-UK radiology template (PAncreatic Cancer reporting Template-UK), and the potential future role of artificial intelligence in the diagnosis and staging of pancreatic cancer.

Automated deep learning-based bone mineral density assessment for opportunistic osteoporosis screening using various CT protocols with multi-vendor scanners

This retrospective study examined the diagnostic efficacy of automated deep learning-based bone mineral density (DL-BMD) measurements for osteoporosis screening using 422 CT datasets from four vendors in two medical centers, encompassing 159 chest, 156 abdominal, and 107 lumbar spine datasets. DL-BMD values on L1 and L2 vertebral bodies were compared with manual BMD (m-BMD) measurements using Pearson’s correlation and intraclass correlation coefficients. Strong agreement was found between m-BMD and DL-BMD in total CT scans (r = 0.953, p < 0.001). The diagnostic performance of DL-BMD was assessed using receiver operating characteristic analysis for osteoporosis and low BMD by dual-energy x-ray absorptiometry (DXA) and m-BMD. Compared to DXA, DL-BMD demonstrated an AUC of 0.790 (95% CI 0.733–0.839) for low BMD and 0.769 (95% CI 0.710–0.820) for osteoporosis, with sensitivity, specificity, and accuracy of 80.8% (95% CI 74.2–86.3%), 56.3% (95% CI 43.4–68.6%), and 74.3% (95% CI 68.3–79.7%) for low BMD and 65.4% (95% CI 50.9–78.0%), 70.9% (95% CI 63.8–77.3%), and 69.7% (95% CI 63.5–75.4%) for osteoporosis, respectively. Compared to m-BMD, DL-BMD showed an AUC of 0.983 (95% CI 0.973–0.993) for low BMD and 0.972 (95% CI 0.958–0.987) for osteoporosis, with sensitivity, specificity, and accuracy of 97.3% (95% CI 94.5–98.9%), 85.2% (95% CI 78.8–90.3%), and 92.7% (95% CI 89.7–95.0%) for low BMD and 94.4% (95% CI 88.3–97.9%), 89.5% (95% CI 85.6–92.7%), and 90.8% (95% CI 87.6–93.4%) for osteoporosis, respectively. The DL-based method can provide accurate and reliable BMD assessments across diverse CT protocols and scanners.

Optimized versus conventional trigger threshold for pancreatic phase image acquisition using dual-energy CT at 40-keV: a randomized controlled trial.

To evaluate the impact of optimized trigger threshold on 40-keV pancreatic phase images acquired with a dual-energy CT (DECT) protocol. A cohort of 69 consecutive participants (median age, 72 years) undergoing a pancreatic protocol DECT examination between September to December 2021 were prospectively randomized into two protocols: conventional trigger threshold of 100 HU (Group A, n = 34) and optimized trigger threshold of 30 HU (Group B, n = 35). Pancreatic phase image acquisition was performed with fixed delay of 20s from the trigger threshold. Two radiologists assessed the 40-keV pancreatic phase images for scan timing adequacy using a binary scale (adequate or inadequate). The proportions of these classifications were compared in the two groups using the Fisher's test. The median times to achieve the aortic attenuation of 30 HU and 100 HU were 16.3s and 22.3s in Group A, respectively, and was 17.8s for 30 HU in Group B. The median time difference from 30 HU to 100 HU was 4.5s in Group A. The scan timing adequacies of pancreatic phase images were classified as adequate (50.0% and 74.3%) or inadequate (50.0% and 25.7%) in Group A and Group B (P = 0.049). An optimized trigger threshold of 30 HU allows consistent acquisition of adequate pancreatic phase images compared to the conventional trigger threshold of 100 HU for pancreatic protocol DECT at 40-keV which might lead to improved pancreatic lesion conspicuity.

Standardized diagnosis of gastrointestinal tumors: an update regarding the situation in Germany.

To evaluate the current status of the diagnosis of gastrointestinal tumors in Germany by means of a survey of the oncological imaging working group of the German Radiological Society (DRG) with a focus on the CT protocols being used.Radiologists working in outpatient or inpatient care in Germany were invited. The survey was conducted between 10/2022 and 06/2023 using the SurveyMonkey web tool. Questions related to gastrointestinal cancer were asked with regard to the commonly used imaging modalities, body coverage, and contrast agent phases in CT as well as the use of oral or rectal contrast. The results of the survey were analyzed using descriptive statistics.Clear differences were identified regarding the acquired contrast phases in relation to the place of work - outpatient care, smaller hospitals, maximum care hospitals, or university hospitals. Variances were also recognized regarding oral and rectal contrast. Based on the results and international guidelines, proposals for CT protocols were derived.CT protocols in Germany show a heterogeneous picture regarding acquired contrast phases, as well as oral and rectal contrast for the staging of gastrointestinal cancer. Clear recommendations in the respective guidelines would aid in quality assurance and comparability between different centers. · The examination protocols for the staging of gastrointestinal tumors are heterogeneous in Germany.. · The application of oral and rectal contrast is handled differently at the various radiological centers.. · Standardization of imaging should be targeted.. · Gerwing M, Ristow I, Afat S et al. Standardized diagnosis of gastrointestinal tumors: an update regarding the situation in Germany. Fortschr Röntgenstr 2024; DOI 10.1055/a-2378-6451.

Performance of Lung-Nodule Computer-Aided Detection Systems on Standard-Dose and Low-Dose Pediatric CT Scans: An Intraindividual Comparison.

Background: When applying lung-nodule computer-aided detection (CAD) systems for pediatric CT, performance may be degraded on low-dose scans due to increased image noise. Objective: To conduct an intraindividual comparison of the performance for lung nodule detection of two CAD systems trained using adult data between low-dose and standard-dose pediatric chest CT scans. Methods: This retrospective study included 73 patients (32 female, 41 male; mean age, 14.7 years; age range, 4-20 years) who underwent both clinical standard-dose and investigational low-dose chest CT examinations within the same encounter from November 30, 2018 to August 31, 2020 as part of an earlier prospective study. Fellowship-trained pediatric radiologists annotated lung nodules to serve as the reference standard. Both CT scans were processed using two publicly available lung-nodule CAD systems previously trained using adult data: FlyerScan and Medical Open Network for Artificial Intelligence (MONAI). The systems' sensitivities for nodules measuring 3-30 mm (n=247) were calculated when operating at a fixed frequency of two false-positives per scan. Results: FlyerScan exhibited detection sensitivities of 76.9% (190/247; 95% CI: 73.3-80.8%) on standard-dose scans and 66.8% (165/247; 95% CI: 62.6-71.5) on low-dose scans. MONAI exhibited detection sensitivities of 67.6% (167/247, 95% CI: 61.5-72.1) on standard-dose scans and 62.3% (154/247, 95% CI: 56.1-66.5%) on low-dose scans. The number of detected nodules for standard-dose versus low-dose scans for 3-mm nodules was 33 versus 24 (FlyerScan) and 16 versus 13 (MONAI), 4-mm nodules was 46 versus 42 (FlyerScan) and 39 versus 30 (MONAI), 5-mm nodules was 38 versus 33 (FlyerScan) and 32 versus 31 (MONAI), and 6-mm nodules was 27 versus 20 (FlyerScan) and 24 versus 24 (MONAI). For nodules measuring ≥7 mm, detection did not show a consistent pattern between standard-dose and low-dose scans for either system. Conclusions: Two lung-nodule CAD systems demonstrated decreased sensitivity on low-dose versus standard-dose pediatric CT scans performed in the same patients. The reduced detection at low dose was overall more pronounced for nodules measuring less than 5 mm. Clinical Impact: Caution is needed when using low-dose CT protocols in combination with CAD systems to help detect small lung nodules in pediatric patients.

7446 Primary Adrenal Mature Teratoma Initially Diagnosed As An Adrenal Myelolipoma

Abstract Disclosure: A. White-Cotsmire: None. B. Kodali: None. A.M. Avram: None. S.S. Shah: None. Background: Teratomas are a type of germ cell tumor containing different types of tissue (e.g., hair, teeth, bone adipose, muscle). Most teratomas are benign (i.e., mature), but they may also be malignant (i.e., immature). Both immature and mature teratomas contain derivatives of ectoderm, endoderm, and mesoderm; however, immature teratomas are differentiated by the presence of embryonic, usually neuroectodermal, tissue. Mature teratomas have the potential for malignant transformation (1–2% of cases), usually squamous cell carcinoma within the teratoma. Extra-gonadal teratomas are rare (only 1–5%); reported locations include sacrococcygeal, head and neck, retroperitoneum, mediastinum, brain and spine, liver, and rarely adrenal glands. (1) Only 18 cases of adult primary adrenal teratomas have been reported since 1952. (2)Clinical Case: A 48-year-old woman with 4 days of worsening abdominal pain underwent CT imaging, which demonstrated a 6cm complex left adrenal mass containing peripheral and scattered internal-coarse calcifications with internal soft tissue and fat components, suggestive of adrenal myelolipoma with probable sequela of previous hemorrhage. Subsequent endocrine follow-up ruled out a cortisol secreting tumor with a negative dexamethasone suppression test and pheochromocytoma with normal serum free metanephrines and normetanephrines. Dedicated adrenal protocol CT scan further characterized the mass as a mature adrenal teratoma containing a rudimentary mandible and two teeth within the soft tissue associated with internal microscopic fat. The left renal vein was anteriorly displaced by this left adrenal mass and severely narrowed by the large adrenal mass, with development of left retroperitoneal collateral venous drainage from the left kidney into the lumbar venous system. The patient opted for conservative management with active clinical surveillance. Conclusion: This is a rare case of adrenal mature teratoma in an adult, originally diagnosed as an adrenal myelolipoma. This case highlights the use of more dedicated adrenal imaging for the characterization of adrenal tumors and the broad differential of benign non-functional adrenal tumors, including myelolipomas, lipomas, angiomyolipomas, and nonfunctional adenomas. However, a definitive diagnosis can only be confirmed by surgical removal of the tumor, usually through a laparoscopic approach, with histopathologic evaluation.

Image quality of virtual monochromatic and material density iodine images for evaluation of head and neck neoplasms using deep learning-based CT image reconstruction – A retrospective observational study

PurposeTo compare the quality of deep learning image reconstructed (DLIR) virtual monochromatic images (VMI) and material density (MD) iodine images from dual-energy computed tomography (DECT) for the evaluation of head and neck neoplasms with CT scans from a conventional single-energy protocol. MethodA total of 294 head and neck CT scans (98 VMIs operated at 60 keV, 102 MD iodine images, and 94 images from a 120 kVp single-energy CT (SECT) protocol) were retrospectively evaluated. VMIs and MD iodine images were generated using the Gemstone Spectral Imaging (GSI) mode using DLIR and metal artifact reduction (MAR) algorithms. SECT images were generated using adaptive statistical iterative reconstruction (ASIR-V). Images were scored by two independent readers on a 6-point Likert-type scale for overall image quality, vessel contrast, soft tissue contrast, noise texture, noise intensity, artifact reduction, and sharpness. ResultsSubjective overall image quality was rated as superior or excellent in 98 % of DLIR-based MD iodine images and VMIs, but only in 55 % of ASIR-V-based SECT images. For each individual quality criterion, image quality of VMIs and MD iodine images was rated as better than that of SECT images (p < 0.001 in each case). Noise texture and intensity were rated better in MD iodine images than in VMIs. ConclusionDECT using both DLIR and MAR for the generation of VMIs and MD iodine images resulted in higher subjective quality of oncologic head and neck images than ASIR-V-based SECT. Noise reduction and noise texture were best achieved with DLIR-based MD iodine images.

A Multidisciplinary Assessment of Standard Low Dose Versus Ultra-low Dose Chest CT Scans for Pectus Excavatum Imaging

AimEvaluation of ultra-low dose chest CT imaging for the assessment of pectus excavatum severity as determined by pediatric radiologists and pediatric surgeons using Haller (HI) and Correction indices (CI). MethodsA single institution, prospective evaluation of patients being evaluated for pectus excavatum were scanned with a standard low-dose chest CT protocol (CARE) followed by a consecutive ultra-low dose CT scan (ULTRA). 3 surgeons and 4 radiologists were instructed to determine HI and CI in each series. The Intraclass Correlation Coefficient (ICC) was used to calculate the agreement level between CARE and ULTRA. Bland–Altman (BA) and scatter plots were also performed to determine bias of each approach. Results32 patients had CARE and ULTRA consecutively. The ICC for HI demonstrated good reliability with a value of 0.89 and excellent reliability for CI with a value of 0.91. The reliability for HI was greater in the surgeon group (0.89) compared to the radiologist group (0.88). The reliability for CI was greater in the radiologist group (0.92) compared to the surgeon group (0.90). The Bland Altman plots for the HI and CI demonstrate no consistent bias for CARE or ULTRA approach when evaluating HI and CI. ConclusionUltra-low dose CT scan imaging compared to standard low-dose CT appears to be a reliable alternative for evaluating PE severity as assessed by HI and CI. This work supports the evaluation and potential development of a standardized CT imaging protocol capable of reducing radiation exposure without sacrificing imaging for PE patients. Level of Evidence2.

Optimizing CT Protocols: Advanced Dose Reduction and Contrast Media Strategies for Personalized Patient Care – Today's Innovations and Tomorrow's Horizons

Optimizing CT Protocols: Advanced Dose Reduction and Contrast Media Strategies for Personalized Patient Care – Today's Innovations and Tomorrow's Horizons

Diagnostic performance of CT/MRI LI-RADS v2018 in non-cirrhotic hepatitis C virus infection.

To evaluate the diagnostic performance of LI-RADS among patients with non-cirrhotic hepatitis C virus (HCV) infection. This retrospective, IRB-approved, single-center study included 66 observations from 43 adult patients (11 women, 32 men; median age 65 years). All patients received liver protocol CT or MRI from 2010 to 2023, had HCV, and did not have cirrhosis based on histopathology. Three board-certified abdominal radiologists blinded to histopathology and imaging follow-up assessed each observation for major features and final LI-RADS category, and inter-reader agreements with weighted kappa were calculated. The positive predictive value, sensitivity, specificity, and accuracy of in diagnosing HCC and overall malignancy was calculated. Of the 66 observations, 53 (80%) were malignant and 13 (20%) were benign. Positive predictive value for HCC was 0-0% for LR-1, 0-0% for LR-2, 0-33% for LR-3, 57-100% for LR-4, 98-100% for LR-5, 25-50% for LR-M, and 83-100% for LR-TIV. Positive predictive value for overall malignancy was 0-0% for LR-1, 0-0% for LR-2, 0-33% for LR-3, 57-100% for LR-4, 98-100% for LR-5, 100-100% for LR-M, and 100-100% for LR-TIV. For LR-5 in identifying HCC, sensitivity ranged from 74 to 90%, specificity from 94 to 100%, and accuracy from 80 to 91%. For the composite of LR-5, LR-M, or LR-TIV in identifying overall malignancy, sensitivity was 87-98%, specificity was 92-100%, and accuracy was 89-97%. The inter-reader agreement for major features varied from moderate to substantial, with substantial agreement for the final category. CT/MRI LI-RADS v2018 criteria can be applied to non-cirrhotic HCV patients with near-perfect specificity.

Helical to wide volume acquisition in lumbar spine CT: Structures scoring based analysis

This study aims to compare the effectiveness of standard helical CT (HMCT) and volume CT (VMCT) protocols for lumbar spine imaging in terms of radiation dose and image quality. Two groups of 56 patients each (32 males, 24 females) who underwent lumbar spine CT were evaluated. The first group was imaged using HMCT and the second with VMCT. Dosimetric parameters including CTDIvol, DLP, and SSDE for both protocols were assesed and compared to evaluate radiation exposure. Image quality was assessed through quantitative analysis of Hounsfield Units (HU) and image noise, and qualitative analysis based on anatomical structure scoring by four reviewers. The VMCT protocol significantly reduced the mean CTDIvol (13 ± 3 mGy vs. 26 ± 6 mGy), DLP (270 ± 29 mGy cm vs. 609 ± 71 mGy cm), and effective dose (5 ± 0 mSv vs. 11 ± 1 mSv) compared to HMCT. SSDE was also lower for VMCT (15.6 ± 4.8 mGy) versus HMCT (31.8 ± 9.1 mGy). Despite this reduction in radiation dose, VMCT showed increased image noise across all anatomical regions, though differences in HU values were region-specific. Qualitative scoring revealed that VMCT images were similar in clarity and sharpness to HMCT images, with only marginally lower scores for most structures. VMCT significantly reduces radiation exposure compared to HMCT with observed difference in noise and CT number. The VMCT protocol can represent a promising tool in terms of radiation protection of patients while image quality needs further evaluation to take into consideration other parameters.

Accuracy of Ultralow-Dose Photon-counting CT in the Detection of Lung Changes after Lung Transplant.

Background Data on the diagnostic accuracy of ultralow-dose (ULD) CT protocols for periodic surveillance in recipients of lung transplant are lacking. Purpose To assess the potential for radiation dose reduction using ULD photon-counting CT (PCT) to detect lung abnormalities in recipients of lung transplant during repeat CT follow-up. Materials and Methods Consecutive adult recipients of lung transplant undergoing same-day standard-of-care low-dose (LD) and ULD PCT from March 2023 to May 2023 were prospectively included. The ULD protocols were performed with two target effective doses comprising 20% (hereafter, ULD1) and 10% (hereafter, ULD2) of the standard LD protocol. The 1-mm reconstructions were reviewed by three readers. Subjective image quality, the visibility of certain anatomic structures (using a five-point Likert scale), and the presence of lung abnormalities were independently assessed. The χ2 or t tests were used to evaluate differences between the ULD1 and ULD2 protocols. Results A total of 82 participants (median age, 64 years [IQR, 54-69 years]; 47 male) were included (41 participants for each ULD protocol). The mean effective doses per protocol were 1.41 mSv ± 0.44 (SD) for LD, 0.26 mSv ± 0.08 for ULD1, and 0.17 mSv ± 0.04 for ULD2. According to three readers, the subjective image quality of the ULD images was deemed diagnostic (Likert score ≥3) in 39-40 (ULD1) and 40-41 (ULD2) participants, and anatomic structures could be adequately visualized (Likert score ≥3) in 33-41 (ULD1) and 34-41 (ULD2) participants. The detection accuracy for individual lung anomalies exceeded 70% for both ULD protocols, except for readers 1 and 3 detecting proximal bronchiectasis and reader 3 detecting bronchial wall thickening and air trapping. No evidence of a statistically significant difference in noise (P = .96), signal-to-noise ratio (P = .77), or reader accuracy (all P ≥ .05) was noted between the ULD protocols. Conclusion ULD PCT was feasible for detecting lung abnormalities following lung transplant, with a tenfold radiation dose reduction. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Ciet in this issue.

Survey of CT radiation doses and iodinated contrast medium administration: an international multicentric study.

To assess the relationship between intravenous iodinated contrast media (ICM) administration usage and radiation doses for contrast-enhanced (CE) CT of head, chest, and abdomen-pelvis (AP) in international, multicenter settings. Our international (n = 16 countries), multicenter (n = 43 sites), and cross-sectional (ConRad) study had two parts. Part 1: Redcap survey with questions on information related to CT and ICM manufacturer/brand and respective protocols. Part 2: Information on 3,258 patients (18-96 years; M:F 1654:1604) who underwent CECT for a routine head (n = 456), chest (n = 528), AP (n = 599), head CT angiography (n = 539), pulmonary embolism (n = 599), and liver CT examinations (n = 537) at 43 sites across five continents. The following information was recorded: hospital name, patient age, gender, body mass index [BMI], clinical indications, scan parameters (number of scan phases, kV), IV-contrast information (concentration, volume, flow rate, and delay), and dose indices (CTDIvol and DLP). Most routine chest (58.4%) and AP (68.7%) CECT exams were performed with 2-4 scan phases with fixed scan delay (chest 71.4%; AP 79.8%, liver CECT 50.7%) following ICM administration. Most sites did not change kV across different patients and scan phases; most CECT protocols were performed at 120-140 kV (83%, 1979/2685). There were no significant differences between radiation doses for non-contrast (CTDIvol 24 [16-30] mGy; DLP 633 [414-702] mGy·cm) and post-contrast phases (22 [19-27] mGy; 648 [392-694] mGy·cm) (p = 0.142). Sites that used bolus tracking for chest and AP CECT had lower CTDIvol than sites with fixed scan delays (p < 0.001). There was no correlation between BMI and CTDIvol (r2 ≤ - 0.1 to 0.1, p = 0.931). Our study demonstrates up to ten-fold variability in ICM injection protocols and radiation doses across different CT protocols. The study emphasizes the need for optimizing CT scanning and contrast protocols to reduce unnecessary contrast and radiation exposure to patients. The wide variability and lack of standardization of ICM media and radiation doses in CT protocols suggest the need for education and optimization of contrast usage and scan factors for optimizing image quality in CECT. There is a lack of patient-centric CT protocol optimization taking into consideration mainly patients' size. There is a lack of correlation between ICM volume and CT radiation dose across CT protocol. A ten-fold variation in iodine-load for the same CT protocol in sites suggests a lack of standardization.

Eastern Health, Box Hill Hospital and Maroondah Hospital. Melbourne, Australia.

Box Hill Hospital has approximately 750 stroke presentations per annum and in 2023, 99 patients received thrombolysis and 40 were transferred out for thrombectomy. Thrombolysis rates, for patients with ischaemic stroke that present within 4.5 hours of symptom onset, was at 37%, with a median door-to-needle (DNT) of 41 minutes, 86% of cases being treated under 60 minutes of arrival and our fastest DNT being 16 minutes. Meidan DIDO was 47 minutes with the fastest recorded 17 minutes. Reperfusion time metrics have improved significantly over the years with the biggest impact being from a direct to CT protocol, organisational coordination and the presence of an Acute Stroke Nurse (ASN) for patients receiving thrombolysis.

A reference framework for standardization and harmonization of CT radiomics features on cadaveric sample

Radiomics features (RFs) serve as quantitative metrics to characterize shape, density/intensity, and texture patterns in radiological images. Despite their promise, RFs exhibit reproducibility challenges across acquisition settings, thus limiting implementation into clinical practice. In this investigation, we evaluate the effects of different CT scanners and CT acquisition protocols (KV, mA, field-of-view, and reconstruction kernel settings) on RFs extracted from lumbar vertebrae of a cadaveric trunk. Employing univariate and multivariate Generalized Linear Models (GLM), we evaluated the impact of each acquisition parameter on RFs. Our findings indicate that variations in mA had negligible effects on RFs, while alterations in kV resulted in exponential changes in several RFs, notably First Order (94.4%), GLCM (87.5%), and NGTDM (100%). Moreover, we demonstrated that a tailored GLM model was superior to the ComBat algorithm in harmonizing CT images. GLM achieved R2 > 0.90 in 21 RFs (19.6%), contrasting ComBat's mean R2 above 0.90 in only 1 RF (0.9%). This pioneering study unveils the effects of CT acquisition parameters on bone RFs in cadaveric specimens, highlighting significant variations across parameters and scanner datasets. The proposed GLM model presents a robust solution for mitigating these differences, potentially advancing harmonization efforts in Radiomics-based studies across diverse CT protocols and vendors.

Feasibility of a single-phase portal venous CT protocol using bolus tracking technique and lean body weight-based contrast media dose.

To evaluate the impact of the use of lean body weight (LBW)-based contrast material (CM) dose and bolus tracking technique on portal venous phase abdominal CT image quality. IRB-approved prospective study; informed consent was acquired. In the period July-November 2023, we randomly selected 105 oncologic patients scheduled for a portal venous phase abdominal CT to undergo our experimental protocol (i.e., 0.7 gI/Kg of LBW CM administration and bolus tracking on the liver). Included patients had performed a "standard" portal venous phase abdominal CT (i.e., 0.6 gI/Kg of total body weight (TBW) contrast material administration and 70 s fixed delay) on the same scanner within the previous 12 months. One reader evaluated CT images measuring liver, portal vein, kidney cortex, and spleen attenuation; values were normalized to paraspinal muscles. Median administered contrast dose (350 mgI/mL CM) was 99 mL (IQR: 81-115 mL) using the experimental protocol and 110 mL (IQR: 100-120 mL) using the standard one (p < 0.0001). Median acquisition delay using the experimental protocol was 65" (IQR 59-73"). Median normalized hepatic enhancement was significantly higher using the experimental protocol (1.97, IQR: 1.83-2.47 vs. 1.86, IQR: 1.58-2.11; p < 0.0001). Median normalized portal vein enhancement was significantly higher using the experimental protocol (3.43, IQR: 2.73-4.04 vs. 2.91, IQR: 2.58-3.41; p < 0.0001). No statistically significant differences were found in the kidneys' cortex and aorta normalized enhancement (p > 0.05). The combination of LBW-based CM dose administration and bolus tracking allows a significant CM dose reduction and a significant liver and portal vein enhancement increase. Lean body weight-based contrast material (CM) dose administration and bolus tracking technique in portal venous phase CT scans overcome differences in body composition and hemodynamics, improving reproducibility. It allows a significant CM dose reduction with increased liver and portal vein enhancement. Lean body weight (LBW)-based contrast material (CM) dosing could be superior to total body weight dosing. Portal venous phase CT with a liver bolus tracking technique improved liver and spleen enhancement with a reduced contrast dose. The combination of LBW-based CM dosing and liver bolus tracking technique enables more "customized" CT examinations.