Journal of Computer Assisted Tomography最新文献

Objective: The second-generation motion correction algorithm, Snapshot Freeze 2.0 (SSF2), is designed to suppress coronary artery motion in cardiac CT angiography. This study aimed to evaluate whether SSF2 improves unenhanced CT images and to compare the coronary artery calcium score (CACS) values reconstructed with and without SSF2.

Methods: One hundred nineteen patients with coronary artery calcium (CACS >0) were enrolled in this study. Unenhanced CT for CACS was performed with a phase window limited to 75% of the R-R interval, using 120 kVp and automatic tube current modulation. CACS values were measured on images with and without SSF2, and absolute differences were calculated. Two radiologists assessed the overall image quality, focusing on coronary artery motion, using a 4-point scale (1=uninterpretable, 4=no motion artifacts).

Results: The absolute differences in CACS for patients with heart rates of 60-95 bpm (n=85) were larger than those with heart rates of up to 59 bpm (n=21) or above 95 bpm (n=13) (median: 10.6, range: 0.1 to 171.2; median: 9.3, range: 0.8 to 31.8; median: 6.0, range: 1.6 to 43.4, respectively). In patients with heart rates of 60 to 95 bpm, SSF2 improved image quality scores ( P <0.001); however, for heart rates of up to 59 bpm or above 95 bpm, the improvements were not significant ( P =0.18 and 0.10, respectively).

Conclusions: SSF2 reduces motion artifacts in the coronary arteries on unenhanced CT and significantly alters the CACS values. A more accurate calcification assessment is anticipated with SSF2, especially in patients with heart rates of 60 to 95 bpm.

Objective: Primary hyperparathyroidism (PHPT) is commonly caused by parathyroid adenomas (PAs), and four-dimensional computed tomography (4DCT) is increasingly used for localising PAs due to its high sensitivity and specificity. However, the relative high radiation dose of 4DCT may limit its widespread use as first line imaging in some settings. A reduced phase protocol and enhancement maps, which highlight relative enhancement differences between the nonenhanced and arterial phases, have been proposed as ways to reduce radiation exposure without compromising diagnostic accuracy. This study aims to assess whether reduced 4DCT protocols can maintain diagnostic performance and if the enhancement map can further assist in adenoma localisation.

Methods: This retrospective study included 27 PHPT patients, with both single and double adenomas, and some ectopic cases and 3 secondary HPT patients. Five-phase combinations derived from our institution's 4-phase protocol were evaluated using a multireader, multicase approach involving experienced neuroradiologists and general radiologists. The phases tested included combinations of nonenhanced, arterial, venous, and delayed venous phases. An enhancement map was introduced as one of the phases. Readers were asked to identify adenomas and assign confidence levels. Performance metrics, including sensitivity, specificity, and area under the curve (AUC), were calculated, and noninferiority tests compared the results to the current 4-phase protocol.

Results: Sensitivity of the total group was between 0.64 and 0.70 with a specificity between 0.94 and 0.97. AUC were between 0.80 and 0.84. All reduced phase combinations were noninferior to the 4-phase protocol. Neuroradiologists achieved noninferior results with 1-phase to 3-phase protocols, while general radiologists required at least 3-phases. The enhancement map did not improve sensitivity or specificity, although readers found it useful as a supplementary tool for identifying lesions. Artefacts, especially in ectopic locations, reduced its effectiveness.

Conclusions: This study supports the use of reduced 4DCT protocols for PHPT. A 1-phase or 2-phase protocol is recommended for experienced radiologists, while a 3-phase protocol is suitable for less experienced radiologists.

Claustrophobia during MRI is a well-documented challenge that affects diagnostic accuracy and patient care. Each year, nearly 2 million MRI scans are disrupted due to anxiety, thus leading to early termination of the scan, image degradation from motion, and increasing healthcare costs. This review examines the prevalence of MRI-related claustrophobia, along with the financial and operational burdens. This review also highlights the latest strategies to improve patient tolerance, which range from technological advancements, behavioral techniques and pharmacological interventions, all of which show promise in reducing scan-related distress. Ultimately, a holistic patient-centered approach is key to optimizing both imaging efficiency and the overall MRI experience.

Objective: To assess the agreement between cardiac computed tomography (CCT) and cardiac magnetic resonance (CMR) for measuring left ventricular (LV) and left atrial (LA) function, and to evaluate the influence of segmentation approach and volume calculation method.

Methods: This retrospective study included 24 patients (mean age 74.2±10.9 y; 54% male) who underwent CMR and multiphase CCT within 14 days. LV and LA end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), and LV mass were measured using CCT voxel-based volumetry with papillary-inclusion (PIS) and exclusion (PES) segmentations and then compared with CMR. Simulations of Simpson's Area-Length (AL) and Disk-Summation (DS) techniques were performed on reformatted CCT images using increasing slice spacings (1 to 32 mm). Agreement was evaluated using correlation coefficients, intraclass correlation coefficients (ICC), percent error, and Bland-Altman analysis.

Results: CCT demonstrated excellent correlation with CMR for LV-EDV, ESV, EF, and mass (r=0.82 to 0.98; ICC=0.72 to 0.94). PES yielded no EF bias, while PIS overestimated EF by 7.0%. LV mass was consistently overestimated by 39 to 52 g (P<0.01). LA volumes showed moderate-to-strong correlation (r=0.70 to 0.90), but poor-to-moderate agreement (ICC=0.21 to 0.55). Simulated LA Simpson-DS measurements with slice spacings ≤8 mm preserved agreement with voxel-based values (ICC ≥0.99).

Conclusions: CCT can accurately assess LV function when compared with CMR when using voxel-based methods and consistent papillary segmentation approaches. Biplane and measurements with wide slice spacings reduce agreement, warranting standardization for clinical interchangeability.

Objective: The effect of hepatic steatosis on liver 18F-FDG uptake remains unclear, as previous PET/CT-based studies have reported inconsistent findings. This study aimed to investigate the impact of hepatic steatosis on 18F-FDG uptake and to identify the factors influencing the liver standardized uptake value (SUV) using PET/MRI.

Methods: A total of 188 participants who underwent PET/MRI for cancer screening between January 2017 and December 2021 were evaluated. The liver fat fraction was quantified using MRI proton density fat fraction (PDFF). Participants were classified into 3 groups based on PDFF thresholds: normal (<6%), mild steatosis (6% to 17%), and moderate-to-severe steatosis (>17%). Liver SUVmax and SUVmean were measured and analyzed for correlations with age, body mass index (BMI), serum lipids, PDFF, and iron deposition. Multivariate and segmented regression analyses were performed to identify independent predictors of liver SUV.

Results: Liver SUVmax and SUVmean increased with mild steatosis but decreased with moderate-to-severe steatosis (P<0.001). Triglyceride (β=0.068, P=0.002), high-density lipoprotein cholesterol (β=-0.295, P=0.001), body mass index (β=0.018, P=0 .037), and age (β=0.007, P=0.007) independently predicted liver SUVmean. PDFF was positively associated with SUVmean in normal livers but negatively associated with fatty livers.

Conclusions: PET/MRI demonstrated that hepatic steatosis, as assessed by PDFF, significantly influenced liver 18F-FDG uptake in a biphasic manner. These findings underscore the importance of integrating fat quantification into PET interpretation to improve the accuracy of oncologic imaging.

Objective: To assess the impact of split-bolus (SB) single scan CT on the conspicuity of clear cell renal cell carcinoma (ccRCC) metastases compared with single-bolus injection.

Methods: This retrospective cohort study included consecutive patients with histologically proven metastatic ccRCC who underwent both SB and single-bolus portal venous abdominal CT within 6 months between 2017 and 2022 in a single tertiary center. SB CT utilized BMI-adjusted contrast dose and kVp (80 to 120) with concurrent arterial and portal venous phases. Single bolus CT utilized BMI-adjusted contrast dose at 120 kVp at the portal venous phase. Wilcoxon rank test compared the conspicuity of metastases between the protocols.

Results: Of the 47 patients, 80.9% were male, with a mean age of 67±10.4 years and a BMI of 27.1±5.7. There were 48 paired CTs performed with a median interval of 93 days. Contrast dose was 143±27 ml for SB and 108±26 ml for single-bolus (P<0.001). Sixty-six metastases were analyzed, with an average size of 2 cm: 48.5% in the pancreas, 28.8% in skeletal muscle, and 22.7% in the liver. The median contrast-to-noise ratio (CNR) was higher with SB compared with single-bolus for all metastases (3.0 vs. 1.4), pancreatic metastases (2.7 vs. 1.4), muscle metastases (5.2 vs. 2.0), and liver metastases (2.8 vs. 0.9), all P<0.001.

Conclusions: SB scan provides dramatically higher conspicuity of ccRCC metastases as compared with single-bolus portal venous CT.

Objective: Coronary computed tomography angiography (CTA) plays a pivotal role in the diagnosis of coronary heart disease in elderly hypertensive patients. This study aimed to investigate the hemodynamic changes in terms of dynamic characteristics, magnitude, and duration following intravenous bolus injection of iodinated contrast media.

Methods: Thirty-two medicated hypertensive patients and 32 nonhypertensive patients underwent Iopromide 370-mediated coronary CTA examination (registration number: ChiCTR2300070704). Hemodynamic parameters were determined at 6 predefined time points from 1 minute before injection to 30 minutes postinjection, using a noninvasive hemodynamic monitoring system. Continuous variables were compared using an independent-samples t test. Categorical data were compared using the χ2 test or a nonparametric test based on data distribution. Repeated measures data were analyzed using repeated measures analysis of variance.

Results: The patterns of hemodynamic change were comparable between groups, with most indicators showing a transient increase followed by recovery to baseline. The magnitude of change was more pronounced in the hypertensive group, with most indicators fluctuating within 10% of baseline values. All hemodynamic values during injection correlated well with baseline levels in both groups, with Pearson correlation coefficients ranging from 0.61 to 0.87. No acute allergic-like reactions were observed, and there was no statistically significant difference in physiological responses between groups.

Conclusions: Our findings indicate that Iopromide 370 has favorable safety and tolerability. Greater clinical caution may be warranted for elderly hypertensive patients with cardiovascular comorbidities.

Objective: To investigate the performance of various convolutional neural networks (CNNs) in identifying clear renal cell carcinoma (ccRCC) on MRI and to compare them with radiologists using the clear cell likelihood score (ccLS) algorithm.

Methods: A total of 480 CNN models were retrospectively trained using 1 or 3 (fusion) different types of MR images obtained from 310 patients with pathologically confirmed renal masses (cT1, ≤7 cm). MR images included T2-weighted (T2w), T1-weighted opposed-phase/in-phase (T1wOPIP), and corticomedullary phase (CMphase) contrast-enhanced MR acquisitions. To increase the robustness of classification, a 5-fold cross-validation was performed, and the averaged area under curve (AUC) values were compared among the CNN models. The best performing CNN models were compared with radiologists' performance using the ccLS algorithm.

Results: The performance of CNN models in ccRCC classification was significantly influenced by the choice of models, the type of input images, and image size. The best CNN models for the diagnosis of ccRCC using T2w and all 3 types of images (fusion CNN models) achieved an AUC of 0.79 and 0.8, respectively. Combining these models using logistic regression produced a slightly higher AUC value of 0.83. Radiologists using the ccLS achieved an AUC value of 0.85, which was not statistically different than the T2w+fusion model (P>0.05). Combining the T2w+fusion model and the ccLS achieved an AUC value of 0.86, which was not different than the AUC value using ccLS alone (P>0.05).

Conclusions: A CNN model integrating three different types of MR images demonstrated performance comparable to that of radiologists in the diagnosis of ccRCC.

Objective: To describe the imaging appearances and treatment response patterns of the pancreatic neuroendocrine tumors (panNETs) following radiofrequency ablation (RFA).

Methods: From an internal database, 17 patients (8 male; mean age: 67±14 y) with 18 pathology-proven, localized, nonfunctioning panNETs <3 cm who underwent EUS-RFA for curative intent were included. A total of 32 preablation and 33 postablation scans were included (CT, MRI, or 68Ga-DOTATATE PET). Lesion size and enhancement on CT/MRI were independently assessed by 2 readers, while SUVmax was extracted from the original PET reports by a separate reviewer. The Wilcoxon signed-rank and McNemar tests were performed. Treatment response is defined as a complete response (loss of enhancement and SUVmax), a partial response (decrease in size, enhancement, or SUVmax), or no response (no change).

Results: Mean lesion size decreased from 1.4​​​​​​±0.5​ cm preablation to 0.3±0.5 cm postablation (P<0.0001). Mean SUVmax declined from 17.3±11.2 to 3.1±6.0 (P<0.001). Hyperenhancement was present in 15/18 (83.3%) lesions preablation versus 5/18 (27.8%) postablation (P<0.01). Of these 15 hyperenhancing lesions, 11 were solid, 3 were cystic, and 1 was mixed cystic and solid. Complete response occurred in 12/18 (66.7%) lesions, with either complete disappearance 5/12 (41.4%) or bland cavity formation 7/12 (58.5%). Partial response occurred in 5/18 (27.8%) lesions; 4/5 decreased in size (mean±SD: 1.4±0.5 cm preablation vs. 0.6±0.7 cm postablation), and 3/5 demonstrated decreased SUVmax. One patient with partial response underwent 2 repeat ablations with an ultimate decrease in SUVmax from 34.1 to 5.9. One solid, hyperenhancing pancreatic body lesion demonstrated no response (1.3 cm); preablation SUVmax was 10.8, but they did not undergo postablation DOTATATE PET. One patient developed postablation pancreatitis. Mean clinical follow-up was 650 days (423).

Conclusion: RFA is an emerging treatment for small, nonfunctioning panNET. Postablation imaging findings most commonly included complete resolution of the tumor, decreased enhancement, decreased SUVmax, and formation of a bland cavity. As interest in this technique continues to grow, radiologists' familiarity with expected post-treatment imaging appearances and their associated response patterns is essential for accurate assessment.

Chest CTs done for unrelated reasons have the potential to reveal unsuspected abnormalities and provide complementary information to help direct appropriate management. By thoroughly understanding the diagnostic role and limitations of CT in assessing ventricular size and morphology as well as myocardial attenuation, enhancement, and thickness, radiologists will be better equipped to differentiate between normal and abnormal findings and provide precise, clinically appropriate recommendations.