Thyroid hemiatrophy associated with papillary thyroid carcinoma.

PURPOSE: The present study aimed to investigate CT imaging features, pathological findings, and prognosis in patients with thyroid hemiatrophy (THA) associated with papillary thyroid carcinoma (PTC). METHODS: This retrospective study included 225 patients with histopathologically proven PTC treated by surgical resection who underwent preoperative CT scanning. On CT images, THA was defined as thyroid parenchymal hemiatrophy on the ipsilateral side of PTC. CT findings, overall survival, and disease-free survival were compared between patients with and without THA. Pathological findings were also assessed in PTCs with and without THA. RESULTS: THA was observed in 35 of 225 (16%) patients with PTC. Atrophic thyroid parenchyma was observed in the right lobe of 20 patients (57%) and in the left lobe of the remaining 15 patients (43%). With respect to the solid components within PTCs, contrast-enhanced CT attenuation (114.2 ± 18.2 vs. 126.7 ± 31.3 HU; p < 0.05) and CT attenuation change for contrast-enhanced CT minus unenhanced CT (60.2 ± 18.1 vs. 72.3 ± 31.0 HU; p < 0.05) were significantly lower in PTCs with THA than in those without THA. Histopathologically, almost all PTCs with THA (97%) had keloid-like collagen, which is broad bundles of hypocellular collagen with bright eosinophilic hyalinization, typically observed in keloid. However, no significant differences were observed in the prognosis between the two groups. CONCLUSION: THA was occasionally observed in patients with PTC. Weak contrast-enhancement was distinct characteristic of PTC patients with THA, which is probably caused by keloid-like collagen.

Prognostic value of radiological T category using conventional MRI in patients with oral tongue cancer: comparison with pathological T category.

PURPOSE: This study aimed to compare the radiological tumor (T)-category using multiparametric MRI with the pathological T category in patients with oral tongue squamous cell carcinoma (OTSCC) and to examine which is a better predictor of prognosis. METHODS: This retrospective study included 110 consecutive patients with surgically resected primary OTSCC who underwent preoperative contrast-enhanced MRI. T categories determined by maximum diameter and depth of invasion were retrospectively assessed based on the pathological specimen and multiparametric MRI. The MRI assessment included the axial and coronal T1-weighted image (T1WI), axial T2-weighted image (T2WI), coronal fat-suppressed T2WI, and axial and coronal fat-suppressed contrast-enhanced T1WI (CET1WI). Axial and coronal CET1WI measurements were divided into two groups: measurements excluding peritumoral enhancement (MEP) and measurements including peritumoral enhancement. The prognostic values for recurrence and disease-specific survival after radiological and pathological T categorization of cases into T1/T2 and T3/T4 groups were compared. RESULTS: The T category of MEP on coronal CET1WI was the most relevant prognostic factor for recurrence [hazard ratio (HR) = 3.30, p = 0.001] and the HR was higher than the HR for pathological assessment (HR = 2.26, p = 0.026). The T category determined by MEP on coronal CET1WI was also the most relevant prognostic factor for disease-specific survival (HR = 3.12, p = 0.03), and the HR was higher than the HR for pathological assessment (HR = 2.02, p = 0.20). CONCLUSION: The T category determined by MEP on the coronal CET1WI was the best prognostic factor among all radiological and pathological T category measurements.

Pancreatic cancer detection with dual-energy CT: diagnostic performance of 40 keV and 70 keV virtual monoenergetic images.

PURPOSE: To compare the diagnostic performance of 40 keV and 70 keV virtual monoenergetic images (VMIs) generated from dual-energy CT in the detection of pancreatic cancer. METHODS: This retrospective study included patients who underwent pancreatic protocol dual-energy CT from January 2019 to August 2022. Four radiologists (1-11 years of experience), who were blinded to the final diagnosis, independently and randomly interpreted 40 keV and 70 keV VMIs and graded the presence or absence of pancreatic cancer. For each image set (40 keV and 70 keV VMIs), the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated. The diagnostic performance of each image set was compared using generalized estimating equations. RESULTS: Overall, 137 patients (median age, 71 years; interquartile range, 63-78 years; 77 men) were included. Among them, 62 patients (45%) had pathologically proven pancreatic cancer. The 40 keV VMIs had higher specificity (75% vs. 67%; P < .001), PPV (76% vs. 71%; P < .001), and accuracy (85% vs. 81%; P = .001) than the 70 keV VMIs. On the contrary, 40 keV VMIs had lower sensitivity (96% vs. 98%; P = .02) and NPV (96% vs. 98%; P = .004) than 70 keV VMIs. However, the diagnostic confidence in patients with (P < .001) and without (P = .001) pancreatic cancer was improved in 40 keV VMIs than in 70 keV VMIs. CONCLUSIONS: The 40 keV VMIs showed better diagnostic performance in diagnosing pancreatic cancer than the 70 keV VMIs, along with higher reader confidence.

Determination of arterial invasion in pancreatic ductal adenocarcinoma: what is the best diagnostic criterion on CT?

OBJECTIVES: To investigate the diagnostic performance and interobserver variability in the determination of arterial invasion in pancreatic ductal adenocarcinoma (PDAC) and determine the best CT imaging criterion. METHODS: We retrospectively evaluated 128 patients with PDAC (73 men and 55 women) who underwent preoperative contrast-enhanced CT. Five board-certified radiologists (expert) and four fellows (non-expert]) independently assessed the arterial invasion (celiac, superior mesenteric, splenic, and common hepatic arteries) using a 6-point score: 1, no tumor contact; 2, hazy attenuation ≤ 180°; 3, hazy attenuation > 180°; 4, solid soft tissue contact ≤ 180°; 5, solid soft tissue contact > 180°; and 6, contour irregularity. ROC analysis was performed to evaluate the diagnostic performance and determine the best diagnostic criterion for arterial invasion, with pathological or surgical findings as references. Interobserver variability was assessed using Fleiss's ĸ statistics. RESULTS: Among the 128 patients, 35.2% (n = 45/128) received neoadjuvant treatment (NTx). Solid soft tissue contact ≤ 180° was the best diagnostic criterion for arterial invasion as defined by the Youden Index both in patients who did and did not receive NTx (sensitivity, 100% vs. 100%; specificity, 90% vs. 93%; and AUC, 0.96 vs. 0.98, respectively). Interobserver variability among the non-expert was not inferior to that among the expert (ĸ = 0.61 vs 0.61; p = .39 and ĸ = 0.59 vs 0.51; p < .001 in patients treated with and without NTx, respectively). CONCLUSIONS: Solid soft tissue contact ≤ 180° was the best diagnostic criterion for the determination of arterial invasion in PDAC. Considerable interobserver variability was seen among the radiologists. KEY POINTS: • Solid soft tissue contact ≤ 180° was the best diagnostic criterion for the determination of arterial invasion in pancreatic ductal adenocarcinoma. • Interobserver agreement among non-expert radiologists was almost comparable to that among expert radiologists.

Prognostic Factors of Pretreatment Magnetic Resonance Imaging for Predicting Clinical Outcome in Patients With Parotid Gland Cancer.

PURPOSE: This study aimed to assess the utility of pretreatment magnetic resonance imaging (MRI) in predicting the clinical outcomes of patients with parotid gland cancer. METHODS: A total of 43 patients with histopathologically confirmed primary parotid gland cancer, who underwent pretreatment MRI, were enrolled in this study. All images were retrospectively reviewed, and MRI features were evaluated as possible prognostic factors influencing the progression-free survival (PFS) using the Kaplan-Meier method and Cox proportional hazards regression model. Cox regression analysis was used to estimate the hazard ratios (HRs) with 95% confidence interval (95% CI) values. RESULTS: Kaplan-Meier survival analysis showed that old age (>73 years, P < 0.01), large maximum tumor diameter (>33 mm, P < 0.01), low apparent diffusion coefficient value (≤1.29 ×10 -3 mm 2 /s, P < 0.01), ill-defined margin ( P < 0.01), skin invasion ( P < 0.01), regional nodal metastasis ( P < 0.01), heterogeneous enhancement ( P < 0.05), and high signal intensity ratio on gadolinium-enhanced fat-suppressed T1-weighted images (>2.017, P < 0.05) were significant predictors of worse PFS. Cox proportional hazards regression analysis revealed that regional nodal metastasis (HR, 32.02; 95% CI, 6.42-159.84; P < 0.01) and maximum tumor diameter (HR, 1.04; 95% CI, 1.01-1.08; P < 0.05) were independent predictors of PFS. CONCLUSION: Pretreatment MRI parameters could be prognostic factors of patients with parotid gland cancer. In particular, the maximum tumor diameter and regional nodal metastasis, which were closely associated with T and N classifications, were important prognostic factors in predicting the PFS.

Magnetic Resonance Imaging Features for Differentiating Low-Grade and High-Grade Malignant Peripheral Nerve Sheath Tumors.

OBJECTIVE: This study aimed to assess the usefulness of magnetic resonance imaging (MRI) findings for differentiating low-grade and high-grade malignant peripheral nerve sheath tumors (MPNSTs). METHODS: This study included 31 patients (onset age range, 19-83 years; mean onset age, 57 years; 9 men and 22 women) with 36 histopathologically proven MPNSTs (7 low-grade MPNSTs and 29 high-grade MPNSTs) who underwent preoperative MRI between December 2007 and October 2022. Quantitative and qualitative MRI findings were retrospectively evaluated and compared between the 2 subtypes. RESULTS: The maximum tumor diameter (106.1 ± 64.0 vs 54.9 ± 19.8 mm, P = 0.032) and tumor-to-muscle signal intensity ratio (SIR) of fat-suppressed gadolinium-enhanced T1-weighted images (2.69 ± 1.40 vs 1.62 ± 0.40, P = 0.005) were significantly higher in high-grade MPNSTs than in low-grade MPNSTs. The receiver operating characteristic analysis revealed that the tumor-to-muscle SIR of fat-suppressed gadolinium-enhanced T1-weighted images exhibited the highest area under the curve value (0.88), followed by the maximum tumor diameter (0.76). The sensitivity and specificity of the tumor-to-muscle SIR of fat-suppressed gadolinium-enhanced T1-weighted images for diagnosing high-grade MPNST at an optimal SIR threshold of greater than 1.73 were 90% and 83%, respectively. However, other MRI findings showed no significant differences between the 2 subtypes (P = 0.16-1.00). CONCLUSIONS: Although the MRI findings of low-grade and high-grade MPNST overlapped considerably, the maximum tumor diameter and degree of contrast enhancement can be used to differentiate low-grade MPNST from high-grade MPNST.

MRI-based radiomics analysis for differentiating phyllodes tumors of the breast from fibroadenomas.

OBJECTIVES: To evaluate the diagnostic performance of MRI-based radiomics model for differentiating phyllodes tumors of the breast from fibroadenomas. METHODS: This retrospective study included 88 patients (32 with phyllodes tumors and 56 with fibroadenomas) who underwent MRI. Radiomic features were extracted from T2-weighted image, pre-contrast T1-weighted image, and the first-phase and late-phase dynamic contrast-enhanced MRIs. To create stable machine learning models and balanced classes, data augmentation was performed. A least absolute shrinkage and selection operator (LASSO) regression was performed to select features and build the radiomics model. A radiological model was constructed from conventional MRI features evaluated by radiologists. A combined model was constructed using both radiomics features and radiological features. Machine learning classifications were done using support vector machine, extreme gradient boosting, and random forest. The area under the receiver operating characteristic (ROC) curve (AUC) was computed to assess the performance of each model. RESULTS: Among 1070 features, the LASSO logistic regression selected 35 features. Among three machine learning classifiers, support vector machine had the best performance. Compared to the radiological model (AUC: 0.77 ± 0.11), the radiomics model (AUC: 0.96 ± 0.04) and combined model (0.97 ± 0.03) had significantly improved AUC values (both p < 0.01) in the validation set. The combined model had a relatively higher AUC than that of the radiomics model in the validation set, but this was not significantly different (p = 0.391). CONCLUSIONS: Radiomics analysis based on MRI showed promise for discriminating phyllodes tumors from fibroadenomas. KEY POINTS: • The radiomics model and the combined model were superior to the radiological model for differentiating phyllodes tumors from fibroadenomas. • The SVM classifier performed best in the current study. • MRI-based radiomics model could help accurately differentiate phyllodes tumors from fibroadenomas.

A comparative analysis of MRI findings in endometrial cancer: differentiation between endometrioid adenocarcinoma, serous carcinoma, and clear cell carcinoma.

OBJECTIVE: To assess the magnetic resonance imaging (MRI) findings of endometrial cancers and to reveal the differences between endometrioid carcinoma (EC), serous carcinoma (SC), and clear cell carcinoma (CCC). METHODS: In this study, 274 consecutive patients with histopathologically confirmed endometrial cancer (231 ECs, 25 SCs, and 18 CCCs) who underwent MRI before hysterectomy were enrolled. MRI images were retrospectively reviewed and compared between the three pathologies. RESULTS: The maximum diameters (55.6 ± 34.7 vs. 39.3 ± 21.6 vs. 39.4 ± 26.8 mm) (p < 0.05) and apparent diffusion coefficient (ADC) values (1.11 ± 0.21 vs. 0.84 ± 0.17 vs. 0.86 ± 0.16 × 10-3 mm2/s) (p < 0.01) were significantly greater in CCCs than in ECs and SCs, respectively. Infiltrative growth pattern (33% vs. 6%) (p < 0.01) was more frequent in CCCs than in ECs. Peritoneal dissemination (16% vs. 0%) (p < 0.01) and heterogeneous signal on diffusion-weighted (61% vs. 32%) (p < 0.05) images were more frequent in SCs than in ECs, respectively. Abnormal ascites (12% vs. 11% vs. 0%) and heterogeneous signal on T1-weighted (28% vs. 50% vs. 9%), T2-weighted (64% vs. 72% vs. 36%), and fat-suppressed gadolinium-enhanced T1-weighted (80% vs. 90% vs. 46%) images were more frequent in SCs and CCCs than in ECs, respectively (p < 0.05). CONCLUSIONS: SCs frequently exhibited a heterogeneous signal with peritoneal dissemination and abnormal ascites. Alternatively, CCCs tended to have a larger tumor size and higher ADC values with an infiltrative growth pattern, heterogeneous signal, and abnormal ascites. KEY POINTS: • SCs tend to have a heterogeneous signal intensity with peritoneal dissemination and abnormal ascites compared to ECs. • CCCs tend to have a heterogeneous signal intensity with an infiltrative growth pattern and abnormal ascites compared to ECs. • CCCs have a larger tumor size and higher ADC values compared to ECs and SCs.

Deep learning image reconstruction algorithm for pancreatic protocol dual-energy computed tomography: image quality and quantification of iodine concentration.

OBJECTIVES: To evaluate the image quality and iodine concentration (IC) measurements in pancreatic protocol dual-energy computed tomography (DECT) reconstructed using deep learning image reconstruction (DLIR) and compare them with those of images reconstructed using hybrid iterative reconstruction (IR). METHODS: The local institutional review board approved this prospective study. Written informed consent was obtained from all participants. Thirty consecutive participants with pancreatic cancer (PC) underwent pancreatic protocol DECT for initial evaluation. DECT data were reconstructed at 70 keV using 40% adaptive statistical iterative reconstruction-Veo (hybrid-IR) and DLIR at medium and high levels (DLIR-M and DLIR-H, respectively). The diagnostic acceptability and conspicuity of PC were qualitatively assessed using a 5-point scale. IC values of the abdominal aorta, pancreas, PC, liver, and portal vein; standard deviation (SD); and coefficient of variation (CV) were calculated. Qualitative and quantitative parameters were compared between the hybrid-IR, DLIR-M, and DLIR-H groups. RESULTS: The diagnostic acceptability and conspicuity of PC were significantly better in the DLIR-M group compared with those in the other groups (p < .001-.001). The IC values of the anatomical structures were almost comparable between the three groups (p = .001-.9). The SD of IC values was significantly lower in the DLIR-H group (p < .001) and resulted in the lowest CV (p < .001-.002) compared with those in the hybrid-IR and DLIR-M groups. CONCLUSIONS: DLIR could significantly improve image quality and reduce the variability of IC values than could hybrid-IR. KEY POINTS: Image quality and conspicuity of pancreatic cancer were the best in DLIR-M. DLIR significantly reduced background noise and improved SNR and CNR. The variability of iodine concentration was reduced in DLIR.

Response prediction of neoadjuvant chemoradiation therapy in locally advanced rectal cancer using CT-based fractal dimension analysis.

OBJECTIVES: There are individual variations in neo-adjuvant chemoradiation therapy (nCRT) in patients with locally advanced rectal cancer (LARC). No reliable modality currently exists that can predict the efficacy of nCRT. The purpose of this study is to assess if CT-based fractal dimension and filtration-histogram texture analysis can predict therapeutic response to nCRT in patients with LARC. METHODS: In this retrospective study, 215 patients (average age: 57 years (18-87 years)) who received nCRT for LARC between June 2005 and December 2016 and underwent a staging diagnostic portal venous phase CT were identified. The patients were randomly divided into two datasets: a training set (n = 170), and a validation set (n = 45). Tumor heterogeneity was assessed on the CT images using fractal dimension (FD) and filtration-histogram texture analysis. In the training set, the patients with pCR and non-pCR were compared in univariate analysis. Logistic regression analysis was applied to identify the predictive value of efficacy of nCRT and receiver operating characteristic analysis determined optimal cutoff value. Subsequently, the most significant parameter was assessed in the validation set. RESULTS: Out of the 215 patients evaluated, pCR was reached in 20.9% (n = 45/215) patients. In the training set, 7 out of 37 texture parameters showed significant difference comparing between the pCR and non-pCR groups and logistic multivariable regression analysis incorporating clinical and 7 texture parameters showed that only FD was associated with pCR (p = 0.001). The area under the curve of FD was 0.76. In the validation set, we applied FD for predicting pCR and sensitivity, specificity, and accuracy were 60%, 89%, and 82%, respectively. CONCLUSION: FD on pretreatment CT is a promising parameter for predicting pCR to nCRT in patients with LARC and could be used to help make treatment decisions. KEY POINTS: • Fractal dimension analysis on pretreatment CT was associated with response to neo-adjuvant chemoradiation in patients with locally advanced rectal cancer. • Fractal dimension is a promising biomarker for predicting pCR to nCRT and may potentially select patients for individualized therapy.

Arterial involvement and resectability scoring system to predict R0 resection in patients with pancreatic ductal adenocarcinoma treated with neoadjuvant chemoradiation therapy.

OBJECTIVES: To derive a CT-based scoring system incorporating arterial involvement and resectability status to predict R0 resection in patients with pancreatic ductal adenocarcinoma (PDAC) undergoing neoadjuvant chemoradiation therapy (CRT). METHODS: This retrospective study included 112 patients with PDAC who underwent dynamic contrast-enhanced CT before and after neoadjuvant CRT. A 5-point score was used to determine arterial involvement (A score; 1 = no involvement, 2 = haziness, 3 = abutment, 4 = encasement, 5 = deformity) and 4-point score evaluating resectability status (R score; 1 = resectable, 2 = borderline resectable [BR] with venous involvement, 3 = BR with arterial involvement, 4 = locally advanced [LA]). A score before and after CRT were summed with R score before and after CRT to compute the AR score (ARtotal). The associations between ARtotal, R0 resection, overall survival (OS), and disease-free survival (DFS) were assessed. RESULTS: The ARtotal was associated with R0 resection (p < .001) and showed area under the ROC curve of 0.79 for differentiating R0 and R1 resections. Median OS was significantly lower for patients with ARtotal  > 9 (median: 35.2 months) compared to patients with ARtotal ≤ 9 (median: not estimable) (p < .001). Similar results were observed for DFS (median, 16.8 months in > 9 vs median, not estimable in ≤ 9; p < .001). CONCLUSIONS: A composite score which incorporates degree of arterial involvement and resectability status before and after neoadjuvant CRT is associated with R0 resection and discriminates between R0 and R1 resections in PDAC. KEY POINTS: • A scoring system incorporating arterial involvement and resectability status was associated with R0 resection. • ARtotal > 9 could predict patients' overall and disease-free survival.

Prediction of overall survival in patients with pancreatic ductal adenocarcinoma: histogram analysis of ADC value and correlation with pathological intratumoral necrosis.

BACKGROUND: To evaluate the utility of histogram analysis (HA) of apparent diffusion coefficient (ADC) values to predict the overall survival (OS) in patients with pancreatic ductal adenocarcinoma (PDAC) and to correlate with pathologically evaluated massive intratumoral necrosis (MITN). MATERIALS AND METHODS: Thirty-nine patients were included in this retrospective study with surgically resected PDAC who underwent preoperative magnetic resonance imaging. Twelve patients received neoadjuvant chemotherapy. HA on the ADC maps were performed to obtain the tumor HA parameters. Using Cox proportional regression analysis adjusted for age, time-dependent receiver-operating-characteristic (ROC) curve analysis, and Kaplan-Meier estimation, we evaluated the association between HA parameters and OS. The association between prognostic factors and pathologically confirmed MITN was assessed by logistic regression analysis. RESULTS: The median OS was 19.9 months. The kurtosis (P < 0.001), entropy (P = 0.013), and energy (P = 0.04) were significantly associated with OS. The kurtosis had the highest area under the ROC curve (AUC) for predicting 3-year survival (AUC 0.824) among these three parameters. Between the kurtosis and MITN, the logistic regression model revealed a positive correlation (P = 0.045). Lower survival rates occurred in patients with high kurtosis (cutoff value > 2.45) than those with low kurtosis (≤ 2.45) (P < 0.001: 1-year survival rate, 75.2% versus 100%: 3-year survival rate, 14.7% versus 100%). CONCLUSIONS: HA derived kurtosis obtained from tumor ADC maps might be a potential imaging biomarker for predicting the presence of MITN and OS in patients with PDAC.

MRI findings to differentiate musculoskeletal dedifferentiated liposarcoma from atypical lipomatous tumor.

OBJECTIVE: This study aimed to assess the efficacy of using MRI findings for differentiating musculoskeletal dedifferentiated liposarcoma (DDLP) from atypical lipomatous tumor (ALT). MATERIALS AND METHODS: This study included 22 patients with histopathologically proven DDLP and 35 with ALT in the musculoskeletal areas. All DDLPs were immunohistochemically positive for MDM2. MRI findings for both pathologies were retrospectively reviewed and compared. RESULTS: The maximum lesion diameter was significantly lower in DDLPs than in ALTs (p < 0.01). Ill-defined margin, peritumoral edema, and tail sign were more frequently observed in DDLPs than in ALTs (p < 0.01, respectively). The fatty component was less frequently observed in DDLPs than in ALTs (27 vs. 100%; p < 0.01), whereas the non-fatty component was more frequently observed in DDLPs than in ALTs (100 vs. 11%; p < 0.01). The occupation rate by non-fatty components was significantly higher in DDLPs than in ALTs (p < 0.01). No significant differences were observed in imaging findings associated with fatty component; however, necrosis within the non-fatty component on the contrast-enhanced image was more frequently observed in DDLPs than in ALTs (72 vs. 0%, p < 0.05). CONCLUSION: DDLPs always had a non-fatty component, whereas ALTs always had fatty component. Ill-defined margin, peritumoral edema, tail sign, and necrosis within non-fatty components were useful MRI features for differentiating musculoskeletal DDLP from ALT.

Optimized Bolus Threshold for Dual-Energy CT Angiography with Monoenergetic Images: A Randomized Clinical Trial.

Background The bolus-tracking technique from single-energy CT has been applied to dual-energy CT (DECT) without optimization or validation. Further optimization is imperative because of a paucity of literature and differences in the attenuation profile of virtual monoenergetic images (VMIs). Purpose To determine the optimal trigger threshold with bolus-tracking technique for DECT angiography (DECTA) in a phantom study and assess the feasibility of an optimized threshold for bolus-tracking technique in DECTA at 40 keV with a 50% reduced iodine dose in human participants. Materials and Methods A phantom study with rapid kilovoltage-switching DECT was performed to determine the optimal threshold for each kiloelectron-volt VMI. In a prospective study, consecutive participants who underwent whole-body CT angiography (CTA) from August 2018 to July 2019 were randomized into three groups: single-energy CTA (SECTA) with standard iodine dose (600 mg of iodine per kilogram), DECTA with 50% reduced iodine dose (300 mg of iodine per kilogram) by using a conventional threshold, and DECTA with 300 mg of iodine per kilogram by using an optimized threshold. A trigger threshold of 100 HU at 120 kVp was used as a reference for comparison. Injected iodine doses and aortic CT numbers were compared among the three groups using Kruskal-Wallis test. Results Ninety-six participants (mean age ± standard deviation, 72 years ± 9; 80 men) were evaluated (32 participants in each group). The optimized threshold for VMIs at 40 keV was 30 HU. The median iodine dose was lower in the optimized DECTA group (13 g) compared with conventional DECTA (19 g) and SECTA (26 g) groups (P < .017 for each comparison). The median aortic CT numbers were higher in the order corresponding to conventional DECTA (655-769 HU), optimized DECTA (543-610 HU), and SECTA (343-359 HU) groups (P < .001). Conclusion The optimized trigger threshold of 30 HU for bolus-tracking technique during dual-energy CT angiography at 40 keV achieved lower iodine load while maintaining aortic enhancement. ©RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Malayeri in this issue.

Hepatobiliary contrast uptake patterns on gadoxetic acid-enhanced MRI in liver metastases from pancreatic ductal adenocarcinoma: can it predict prognosis?

OBJECTIVES: To evaluate the relationship between the patterns of hepatobiliary phase (HBP) contrast uptake in liver metastases on gadoxetic acid-enhanced MR imaging and overall survival (OS) in patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: This retrospective study was approved by our institutional review board and written informed consent was waived. A total of 57 patients (30 men and 27 women; age range, 46-92 years; mean age, 64.9 ± 9.2 years) with PDAC and liver metastasis who had undergone gadoxetic acid-enhanced MR imaging were included. The internal morphologies of the nodules were classified as heterogeneous or homogeneous on HBP images (20 min). During patient-by-patient analysis, patients with both patterns of nodules were classified as belonging to the heterogeneous group. Kaplan-Meier analysis and log-rank test were conducted for univariate analysis and Cox proportional hazards regression was conducted for multivariate analysis to evaluate prognostic factors for OS in patients with PDAC and liver metastasis. RESULTS: A total of 199 liver metastases were analyzed, among which 138 nodules (69%) demonstrated heterogeneous hypointensity, while 61 nodules (31%) demonstrated homogeneous hypointensity. Homogeneous hypointense nodules were encountered in 18 patients (32%; homogeneous group), heterogeneous in 29 patients (51%), and both patterns co-existed in 10 patients (17%; heterogeneous group). The heterogeneous group exhibited lower OS rates than the homogeneous group (mean OS, 48.5 months vs 23.9 months; p = 0.032). CONCLUSIONS: Hepatobiliary contrast uptake pattern in liver metastasis on HBP images can be a potential imaging biomarker to predict OS in patients with PDAC and liver metastasis. KEY POINTS: • Majority of the liver metastases were heterogeneous (69%) after gadoxetic acid-enhanced MR imaging. • Patients with heterogeneous hypointense nodules demonstrated lower overall survival rate. • Hepatobiliary contrast uptake pattern in liver metastasis is possibly associated with patients' prognosis.

Low keV portal venous phase as a surrogate for pancreatic phase in a pancreatic protocol dual-energy CT: feasibility, image quality, and lesion conspicuity.

OBJECTIVE: To assess the feasibility of a proposed pancreatic protocol CT generated from portal-venous phase (PVP) dual-energy CT (DECT) acquisition and its impact on image quality, lesion conspicuity, and arterial visualization/involvement. METHODS: We included 111 patients (mean age, 66.8 years) who underwent pancreatic protocol DECT (pancreatic phase, PP, and PVP). The original DECT acquisition was used to create two data sets-standard protocol (50 keV PP/65 keV PVP) and proposed protocol (40 keV/65 keV PVP). Three reviewers evaluated the two data sets for image quality, lesion conspicuity, and arterial visualization/involvement using a 5-point scale. The signal-to-noise ratio (SNR) of pancreas and lesion-to-pancreas contrast-to-noise ratio (CNR) was calculated. Qualitative scores, quantitative parameters, and dose-length product (DLP) were compared between standard and proposed protocols. RESULTS: The image quality, SNR of pancreas, and lesion-to-pancreas CNR of the standard and proposed protocol were comparable (p = 0.11-1.00). Lesion conspicuity was comparable between the standard and proposed protocols for pancreatic ductal adenocarcinoma (p = 0.55) and pancreatic cysts (p = 0.28). The visualization of larger arteries and arterial involvement were comparable between the two protocols (p = 0.056-1.00) while the scores were higher for smaller vessels in the standard protocol (p < 0.0001-0.0015). DLP of the proposed protocol (670.4 mGy·cm) showed a projected 42% reduction than the standard protocol (1145.9 mGy·cm) (p < 0.0001). CONCLUSION: Pancreatic protocol CT generated from a single PVP DECT acquisition is feasible and could potentially be an alternative to the standard pancreatic protocol with PP and PVP. KEY POINTS: • The lesion conspicuity for focal pancreatic lesions was comparable between the proposed protocol and standard dual-phase pancreatic protocol CT. • Qualitative and quantitative image assessments were almost comparable between two protocols. • The radiation dose of a proposed protocol showed a projected 42% reduction from the conventional protocol.

Effect of computed tomography value error on dose calculation in adaptive radiotherapy with Elekta X-ray volume imaging cone beam computed tomography.

PURPOSE: We evaluated the effect of changing the scan mode of the Elekta X-ray volume imaging cone beam computed tomography (CBCT) on the accuracy of dose calculation, which may be affected by computed tomography (CT) value errors in three dimensions. METHODS: We used the electron density phantom and measured the CT values in three dimensions. CT values were compared with planning computed tomography (pCT) values for various materials. The evaluated scan modes were for head and neck (S-scan), chest (M-scan), and pelvis (L-scan) with various collimators and filter systems. To evaluate the effects of the CT value error of the CBCT on dose error, Monte Carlo calculations of dosimetry were performed using pCT and CBCT images. RESULTS: The L-scan had a CT value error of approximately 800 HU at the isocenter compared with the pCT. Furthermore, inhomogeneity in the longitudinal CT value profile was observed in the bone material. The dose error for ±100 HU difference in CT values for the S-scan and M-scan was within ±2%. The center of the L-scan had a CT error of approximately 800 HU and a dose error of approximately 6%. The dose error of the L-scan occurred in the beam path in the case of both single field and two parallel opposed fields, and the maximum error occurred at the center of the phantom in the case of both the 4-field box and single-arc techniques. CONCLUSIONS: We demonstrated the three-dimensional CT value characteristics of the CBCT by evaluating the CT value error obtained under various imaging conditions. It was found that the L-scan is considerably affected by not having a unique bowtie filter, and the S-scan without the bowtie filter causes CT value errors in the longitudinal direction. Moreover, the CBCT dose errors for the 4-field box and single-arc irradiation techniques converge to the isocenter.

Correlation of quantitative pancreatic T1 value and HbA1c value in subjects with normal and impaired glucose tolerance.

BACKGROUND: Signal intensity on T1 -weighted images (T1 WI) is associated with pancreatic fibrosis and HbA1c levels. PURPOSE: To evaluate the feasibility of the pancreatic T1 value for assessment of subjects with normal and impaired glucose tolerance (IGT). STUDY TYPE: A prospective single-institution study. POPULATION: In all, 95 consecutive patients with a known or suspected pancreatic disease. FIELD STRENGTH/SEQUENCES: 3T/fast pancreatic T1 mapping using a modified Look-Locker sequence. ASSESSMENT: Following the American Diabetes Association criteria, patients were classified into three groups, as follows: no-diabetes subject, HbA1c < 5.7%; prediabetes, 5.7% ≤ HbA1c < 6.5%; and type 2 diabetes mellitus (T2DM), HbA1c ≥ 6.5%. Pancreatic T1 value and signal intensity ratio (SIR = SIpancreas /SImuscle ) using T1 WI were compared with the HbA1c values. STATISTICAL TESTS: Quantitative data were assessed with one-way analysis of variance, Fisher's and Mann-Whitney U tests, and receiver-operating characteristic analysis. RESULTS: The pancreatic T1 value was significantly longer in T2DM than in no-diabetes and prediabetes subjects (P < 0.05) and was significantly longer in prediabetes than in no-diabetes subjects (P < 0.05). The mean pancreatic T1 value was significantly lower in the low-value group (HbA1c < 5.7%) (906.3 msec) compared with the high-value group (HbA1c ≥ 6.5%) (993.8 msec) (P < 0.0001). SIR on T1 WI was significantly higher in the low-value group compared with the high-value group (P = 0.029). The sensitivities, specificities, and area under the receiver-operating characteristic curve (AUCs) for differentiating the low- and high-value groups were 74.1%, 83.8%, and 0.82 in the pancreatic T1 values and 77.8%, 54.4%, and 0.63 in SIR on T1 WI, respectively. The specificity (P < 0.0001) and AUC (P = 0.0020) were significantly higher in the pancreatic T1 values than in SIR on T1 WI. DATA CONCLUSION: Pancreatic T1 value has the potential of being an imaging biomarker for the assessment of IGT. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:711-718.

Prognostic evaluation of pancreatic ductal adenocarcinoma: Associations between molecular biomarkers and CT imaging findings.

OBJECTIVES: To investigate association between molecular biomarkers and computed tomography (CT) imaging findings in patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: Fifty-three consecutive patients with PDAC (34 men and 19 women; mean age, 70.6 ±â€¯8.1 years; range, 56-86 years) who underwent dynamic contrast-enhanced CT prior to pancreatectomy were included. The Ki-67 index and expressions of E-cadherin, Vimentin, and TWIST were immunohistochemically evaluated. Qualitative image analysis and histogram analysis of CT numbers were conducted. Clinical and molecular biomarkers were tested as possible prognostic factors for overall survival (OS) using Kaplan-Meier method and Cox proportional hazards regression. In addition, associations between CT imaging findings and significant molecular biomarkers were investigated. RESULTS: The TNM stage (P = 0.018) and E-cadherin expression status (P = 0.018) were independently associated with OS. E-cadherin-negative PDACs had a worse prognosis than E-cadherin-positive PDACs (hazard ratio: 2.21). Irregular tumor margin was observed more frequently in E-cadherin-negative PDACs (54.7%) than in E-cadherin-positive PDACs (45.3%) (P = 0.00054). The kurtosis of CT number during the pancreatic parenchymal phase was significantly higher in E-cadherin-negative PDACs than in E-cadherin-positive PDACs (P = 0.035). CONCLUSIONS: E-cadherin suppression was found to be a prognostic factor for OS in patients with PDAC, and irregular tumor margin and kurtosis of CT numbers during the pancreatic parenchymal phase could be indicators for E-cadherin suppression.