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

PURPOSE: To evaluate the impact of optimized trigger threshold on 40-keV pancreatic phase images acquired with a dual-energy CT (DECT) protocol. METHODS: 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 20 s 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. RESULTS: The median times to achieve the aortic attenuation of 30 HU and 100 HU were 16.3 s and 22.3 s in Group A, respectively, and was 17.8 s for 30 HU in Group B. The median time difference from 30 HU to 100 HU was 4.5 s 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). CONCLUSION: 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.

Quantitative spatial visualization of X-ray irradiation via redox reaction by dynamic nuclear polarization magnetic resonance imaging.

The dose of X-ray irradiation is commonly measured by point assessment with an ionization chamber dosimeter. However, to achieve spatially accurate delivery of X-ray to avoid the exposure to normal tissues, an accurate imaging method for spatially and quantitatively detecting exposure is required. Herein, we present a novel method to visualize X-ray exposure using low-field dynamic nuclear polarization magnetic resonance imaging (DNP-MRI) with nitroxyl radical tempol as the chemical dosimeter. In this system, gel phantoms containing glutathione (GSH) and the paramagnetic tempol radical were used to monitor the deposited X-ray-irradiation via the redox reaction. The tempol radical level was evaluated by DNP-MRI whose signal intensity was linearly correlated with the radical concentration. The radical level in the presence of GSH decreased in proportion to the dose of X-irradiation deposited. In an imaging experiment simulating clinical radiotherapy, we used a clinical linear accelerator with a radiotherapy planning software to confirm the utility of the exposure imaging. The X-ray exposure and its distribution were clearly visualized on the gel phantom image acquired by DNP-MRI. The results were consistent with those specified in the radiotherapy plan where the intensity of the radiation beam was modulated. This exposure estimation will be useful for determining an accurate irradiation field and reducing off-target exposure in clinical settings.

MRI features of histological subtypes of thyroid cancer in comparison with CT findings: differentiation between anaplastic, poorly differentiated, and papillary thyroid carcinoma.

PURPOSE: This study aimed to evaluate the MRI features of the main histological subtypes of thyroid cancer and enable differentiation between anaplastic thyroid carcinoma (ATC), poorly differentiated thyroid carcinoma (PDTC), and papillary thyroid carcinoma (PTC). MATERIALS AND METHODS: This study included 79 patients with histopathologically proven thyroid cancer (14 ATCs, 8 PDTCs, and 57 PTCs) who underwent neck MRI. MRI images were retrospectively reviewed and compared between the three pathologies. RESULTS: The maximum diameter was larger in ATCs and PDTCs than in PTCs (65.2 mm and 38.4 mm vs. 26.0 mm, p < 0.01). The signal intensity ratio of the solid components on T2-weighted images (T2WIs) was higher in ATCs than in PTCs (1.13 vs. 0.89, p < 0.05). The predominant signal intensity of the solid components on T2WI exhibited hyperintensity relative to the spinal cord in ATCs more frequently than in PTCs (71% vs. 30%, p < 0.01), whereas hypointensity was more frequent in PTCs than in ATCs and PDTCs (60% vs. 0% and 13%, p < 0.01). Intratumoral ring-shaped hypointensity on T2WI was more frequent in ATCs than in PDTCs and PTCs (64% vs. 13% and 18%, p < 0.01). An ill-defined margin was more frequent in ATCs and PDTCs than in PTCs (93% and 63% vs. 25%, p < 0.01). Extrathyroidal extension, tracheal invasion, esophageal invasion, vascular invasion, and venous thrombosis were more frequently observed in ATCs than in PTCs (p < 0.05). CONCLUSIONS: MRI could characterize the differences between ATCs, PDTCs, and PTCs.

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.

Diffusion-weighted Echo Planar Imaging with Compressed SENSE (EPICS-DWI) for Pancreas Assessment: A Multicenter Study.

PURPOSE: This study aimed to evaluate the feasibility of single-shot echo planar diffusion-weighted imaging with compressed SENSE (EPICS-DWI) for pancreas assessment by comparing with single-shot echo planar DWI with parallel imaging (PI-DWI). METHODS: This multicenter prospective study included 27 consecutive participants with untreated pancreatic ductal adenocarcinoma (PDAC) (15 men; mean age, 67 ± 10 years) who underwent pancreatic protocol MRI including both PI-DWI and EPICS-DWI. Two radiologists independently and randomly reviewed the high b-value DWI images and qualitatively assigned confidence scores for overall image quality, image noise, pancreas conspicuity, and PDAC conspicuity using a 5-point scale. One radiologist measured the PDAC-to-pancreas contrast-to-noise-ratio (CNR) on high b-value DWI images and the apparent diffusion coefficient (ADC) value of PDAC. Qualitative and quantitative parameters were compared between PI-DWI and EPICS-DWI using the Wilcoxon signed-rank test. RESULTS: The confidence scores for overall image quality (P < 0.001 in both radiologists) and image noise (P < 0.001 in both radiologists) were higher in EPICS-DWI than in PI-DWI. The pancreas conspicuity was better in EPICS-DWI than in PI-DWI in one of the radiologists (P = 0.02 and 0.06). The PDAC conspicuity was comparable between PI-DWI and EPICS-DWI (P > 0.99 in both radiologists). The PDAC-to-pancreas CNR was higher in EPICS-DWI than in PI-DWI (P = 0.02), while the ADC value of PDAC in PI-DWI was not significantly different compared to that in EPICS-DWI (P = 0.48). CONCLUSION: The image quality and PDAC-to-pancreas CNR was improved in EPICS-DWI compared to PI-DWI. However, the conspicuity and ADC value of PDAC were comparable between PI-DWI and EPICS-DWI.

Assessment of Arterial Involvement in Pancreatic Cancer: Utility of Reconstructed CT Images Perpendicular to Artery.

The purpose of this study was to investigate the utility of reconstructed CT images perpendicular to the artery for assessing arterial involvement from pancreatic cancer and compare the interobserver variability between it and the current diagnostic imaging method. This retrospective study included patients with pancreatic cancer in the pancreatic body or tail who underwent preoperative pancreatic protocol CT and distal pancreatectomy. Five radiologists used axial and coronal CT images (current method) and perpendicular reconstructed CT images (proposed method) to determine if the degree of solid soft-tissue contact with the splenic artery was ≤180° or >180°. The generalized estimating equations were used to compare the diagnostic performance of solid soft-tissue contact >180° between the current and proposed methods. Fleiss' ĸ statistics were used to assess interobserver variability. The sensitivity and negative predictive value for diagnosing solid soft-tissue contact >180° were higher (p < 0.001 for each) and the specificity (p = 0.003) and positive predictive value (p = 0.003) were lower in the proposed method than the current method. Interobserver variability was improved in the proposed method compared with the current method (ĸ = 0.87 vs. 0.67). Reconstructed CT images perpendicular to the artery showed higher sensitivity and negative predictive value for diagnosing solid soft-tissue contact >180° than the current method and demonstrated improved interobserver variability.

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.

CT and MRI findings of small cell neuroendocrine carcinoma of the urinary bladder: comparison with urothelial carcinoma.

OBJECTIVE: This study aimed to evaluate the efficacy of CT and MRI findings to differentiate small cell neuroendocrine carcinoma (SCNEC) from urothelial carcinoma (UC) of the urinary bladder. MATERIALS AND METHODS: This study included 90 patients with histopathologically confirmed bladder cancer (10 SCNECs and 80 UCs). Eight patients with bladder SCNEC and 80 with UC underwent CT and MRI, whereas the remaining two patients with SCNEC underwent CT alone before treatment. CT and MRI findings were retrospectively evaluated and compared between the two pathologies. RESULTS: The maximum diameter (36.5 mm vs. 19.0 mm, p < 0.01) and height (22.0 mm vs. 14.0 mm, p < 0.01) of the tumor in bladder SCNEC were higher than in UC. The pedunculated configuration (20% vs. 61%, p < 0.05) and irregular tumor margins (20% vs. 76%, p < 0.01) in bladder SCNEC were less common than in UC. The CT attenuation of the solid component in unenhanced CT images was higher in bladder SCNEC than in UC (37 Hounsfield unit [HU] vs. 34 HU, p < 0.01). The apparent diffusion coefficient (ADC) of the solid component in bladder SCNEC was lower than in UC (0.49 × 10-3 mm2/s vs. 1.02 × 10-3 mm2/s, p < 0.01). CONCLUSION: In comparison with UC, bladder SCNEC was larger, had higher unenhanced CT attenuation, and had a lower ADC value. The pedunculated configuration and irregular tumor margins were typical of bladder UC.

FDG uptake in the cervical muscles after neck dissection: imaging features and postoperative natural course on 18F­FDG­PET/CT.

PURPOSE: This study aimed to assess the imaging features and postoperative natural course of 18F-fluorodeoxyglucose (FDG) uptake in the cervical muscles after neck dissection. MATERIALS AND METHODS: This study included 83 patients who underwent preoperative and postoperative 18F-FDG-PET/CT and were diagnosed with head and neck malignancy after neck dissection. Postoperative 18F-FDG-PET/CT was performed within 5 years after neck dissection. Preoperative and postoperative FDG uptake of the trapezius, sternocleidomastoid, scalene, pectoralis major, and deltoid muscles was visually assessed. Increased postoperative uptake was visually defined as higher postoperative FDG uptake than the preoperative one in the corresponding muscle. The maximum standardized uptake value (SUVmax) was measured in cases with increased postoperative uptakes. RESULTS: Increased postoperative uptakes were observed in 43 patients (52%). The trapezius (31/83, 37%), sternocleidomastoid (19/83, 23%), and scalene (12/83, 14%) muscles were involved, as opposed to the pectoralis major and deltoid muscles were not. Increased postoperative uptakes were observed on the dissected side in all 43 patients. Significant differences between SUVmax estimated from the mixed-effects model and postoperative months were observed in the trapezius muscle (Coefficient (ß) = -0.038; 95% confidence interval (CI): [-0.047, -0.028]; p < 0.001) and sternocleidomastoid muscle (ß = -0.015; 95% CI: [-0.029, -0.001]; p = 0.046). CONCLUSIONS: Increased postoperative uptakes in the cervical muscles were observed on the dissected side in approximately half of the patients after neck dissection. The SUVmax in the trapezius and sternocleidomastoid muscles decreased after surgery over time.

Appropriate pancreatic phase image acquisition by free-breathing dynamic contrast-enhanced pancreatic MRI using stack-of-stars radial sampling and Compressed SENSE.

PURPOSE: To evaluate the feasibility of a free-breathing sequence (4D FreeBreathing) combined with Compressed SENSE in dynamic contrast-enhanced pancreatic MRI and compare it with a breath-holding sequence (eTHRIVE). METHOD: Patients who underwent pancreatic MRI, either eTHRIVE or 4D FreeBreathing, from April 2022 to November 2023 were included in this retrospective study. Two radiologists, who were unaware of the scan sequence, independently and randomly reviewed the images at the precontrast, pancreatic, portal venous, and equilibrium phases and assigned confidence scores for motion and streaking artifacts, pancreatic sharpness, and overall image quality using a 5-point scale. Furthermore, the radiologists assessed the appropriateness of the scan timing of the pancreatic phase. Mann-Whitney U and Fisher's exact tests were conducted to compare the confidence scores and adequacy of the pancreatic phase scan timing between eTHRIVE and 4D FreeBreathing. RESULTS: Overall, 48 patients (median age, 71 years; interquartile range, 64-77 years; 24 women) were included. Among them, 20 patients (42%) were scanned using 4D FreeBreathing. The 4D FreeBreathing showed moderate streaking artifact but improved motion artifact (P <.001-.17) at all phases. Pancreatic sharpness and overall image quality were almost comparable between two sequences (P = .17-.96). All 20 examinations in 4D FreeBreathing showed appropriate pancreatic phase images, but only 16 (57%; P <.001 for reviewer 1) and 18 (64%; P = .003 for reviewer 2) examinations showed it in eTHRIVE. CONCLUSION: The use of 4D FreeBreathing combined with Compressed SENSE was feasible in pancreatic MRI and provided appropriate pancreatic phase images in all examinations.

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.

Radiomics Features Using Dual-energy CT for Lymph Nodes After Preoperative Chemotherapy for Esophageal Cancer.

BACKGROUND/AIM: Progress has been made in a triplet preoperative chemotherapy regimen for advanced esophageal cancer. We performed a preliminary investigation of the radiomics features of pathological lymph node metastasis after neoadjuvant chemotherapy using dual-energy computed tomography (DECT). PATIENTS AND METHODS: From January to December 2022, 36 lymph nodes from 10 patients with advanced esophageal cancer who underwent contrast-enhanced DECT after neoadjuvant chemotherapy and radical surgery in our department were studied. Radiomics features were extracted from iodine-based material decomposition images at the portal venous phase constructed by DECT using MATLAB analysis software. Receiver operating characteristic (ROC) analysis and cut-off values were determined for the presence or absence of pathological metastasis. RESULTS: ROC for the short axis of the pathologically positive lymph nodes showed an AUC of 0.713. Long run emphasis (LRE) within gray-level run-length matrix (GLRLM) was confirmed with a high AUC of 0.812. Sensitivity and specificity for lymph nodes with a short axis >10 mm were 0.222 and 1, respectively. Sensitivity and specificity for LRE within GLRLM were 0.722 and 0.833, respectively. Sensitivity and specificity for small zone emphasis (SZE) within gray-level size zone matrix (GLSZM) were 0.889 and 0.667, and zone percentage (ZP) values within GLSZM were 0.722 and 0.778, respectively. Discrimination of existing metastases using radiomics showed significantly higher sensitivity compared to lymph node short axis >10 mm (odds ratios of LRE, SZE, and ZP: 9.1, 28, and 9.1, respectively). CONCLUSION: Evaluation of radiomics analysis using DECT may enable a more detailed evaluation of lymph node metastasis after neoadjuvant chemotherapy.

Does CT overestimate extra-pancreatic perineural invasion in patients with pancreatic ductal adenocarcinoma following neoadjuvant chemoradiation therapy?

OBJECTIVES: To evaluate the diagnostic performance of CT in the assessment of extra-pancreatic perineural invasion (EPNI) in patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: This retrospective study included 123 patients (66 men; median age, 66 years) with PDAC who underwent radical surgery and pancreatic protocol CT for assessing surgical resectability between September 2011 and March 2019. Among the 123 patients, 97 patients had received neoadjuvant chemoradiation therapy (CRT). Two radiologists reviewed the CT images for evidence of EPNI using a 5-point scale (5 = definitely present, 4 = probably present, 3 = equivocally present, 2 = probably absent, and 1 = definitely absent). Diagnostic performance for assessing EPNI was evaluated with receiver operating characteristic (ROC) curve analysis. RESULTS: The sensitivity, specificity, and area under the ROC curve for assessing EPNI were 98%, 30%, and 0.62 in all patients; 97%, 22%, and 0.59 in patients with neoadjuvant CRT; and 100%, 100%, and 1.00 in patients without neoadjuvant CRT, respectively. False-positive assessment of EPNI occurred in 23% of patients (n = 28/123), and 100% of these (n = 28/28) had received neoadjuvant CRT. There was moderate to substantial agreement between the readers (ĸ = 0.49-0.62). CONCLUSION: Pancreatic protocol CT has better diagnostic performance for determination of EPNI in treatment naïve patients with PDAC and overestimation of EPNI is likely in patients who have received preoperative CRT. ADVANCES IN KNOWLEDGE: Pancreatic protocol CT has better diagnostic performance for the detection of EPNI in treatment naïve patients compared to patients receiving neoadjuvant CRT.

MRI findings of malignant transformation arising from mature cystic teratoma of the ovary: comparison with benign mature cystic teratoma.

OBJECTIVE: This study aimed to evaluate the efficacy of MRI findings to differentiate malignant transformation arising from mature cystic teratoma (MT-MCT) of the ovary from benign mature cystic teratoma (BMCT). MATERIALS AND METHODS: This study included 11 patients with histopathologically proven MT-MCT and 50 with BMCT. Overall, 7 patients with MT-MCT and all 50 with BMCT underwent unenhanced and contrast-enhanced MRIs and 4 with MT-MCT only underwent unenhanced MRIs. The MRI findings were evaluated and compared between the two diseases. RESULTS: The median age (55 vs. 38 years, p < 0.01) and maximum diameter (109 vs. 65 mm, p < 0.01) were higher in MT-MCT than in BMCT. Fat component occupancy was lower in MT-MCT than in BMCT (median, 5% vs. 63%, p < 0.01). Only MT-MCT exhibited irregular tumor margins (64%), peritoneal dissemination (18%), and abnormal ascites (27%). The solid components were more commonly observed in MT-MCT than in BMCT (100% vs. 32%, p < 0.01) on contrast-enhanced images. The maximum diameter of solid components in MT-MCT was larger than that in BMCT (median, 61 mm vs. 14 mm, p < 0.01). In MT-MCT, the common configuration of solid components was endophytic or exophytic sessile (85%), whereas in BMCT, it was endophytic papillary (88%). CONCLUSION: Compared with BMCT, MT-MCT demonstrated a larger maximum diameter, lower occupancy rate of fat components, and sessile solid components. The characteristic configuration of solid components was endophytic or exophytic sessile in MT-MCT and endophytic papillary in BMCT.

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.

Deuterium Magnetic Resonance Imaging Using Deuterated Water-Induced 2H-Tissue Labeling Allows Monitoring Cancer Treatment at Clinical Field Strength.

PURPOSE: An accurate and noninvasive assessment of tumor response following treatment other than traditional anatomical imaging techniques is essential. Deuterium magnetic resonance spectroscopic (MRS) imaging has been demonstrated as an alternative for cancer metabolic imaging by high-field MRI using deuterium-labeled molecules. The study aim was to use 2H tissue labeling and deuterium MRI at clinical field strength for tumor visualization and assessment of three anticancer therapies in pancreatic cancer model mice. EXPERIMENTAL DESIGN: MIA PaCa-2 pancreatic carcinoma and C26 colorectal carcinoma models of BALB/c-nu mice was prepared, and repeated deuterium MRI was performed during the first 10 days of free drinking of 30% D2O to track 2H distribution in tissues. 2H accumulation in the tumor after irradiation, bevacizumab administration, or gemcitabine administration was also measured in MIA PaCa-2-bearing mice. Confirmatory proton MRI, ex vivo metabolic hyperpolarization 13C-MRS, and histopathology were performed. RESULTS: The mouse's whole-body distribution of 2H was visible 1 day after drinking, and the signal intensity increased daily. Although the tumor size did not change 1 and 3 days after irradiation, the amount of 2H decreased significantly. The 2H image intensity of the tumor also significantly decreased after the administration of bevacizumab or gemcitabine. Metabolic hyperpolarization 13C-MRS, proton MRI, and 2H-NMR spectroscopy confirmed the efficacy of the anticancer treatments. CONCLUSIONS: Deuterium MRI at 1.5T proved feasible to track 2H distribution throughout mouse tissues during D2O administration and revealed a higher 2H accumulation in the tumor xenografts. This research demonstrated a promising successful method for preliminary assessment of radiotherapy and chemotherapy of cancer.

Diagnostic ability of diffusion-weighted imaging using echo planar imaging with compressed SENSE (EPICS) for differentiating hepatic hemangioma and liver metastasis.

PURPOSE: To assess the diagnostic abilities of diffusion-weighted imaging (DWI) with parallel imaging (PI-DWI) and that with Compressed SENSE (EPICS-DWI) for differentiating hepatic hemangiomas (HHs) and liver metastases (LMs). METHOD: This prospective study included 30 participants with HH and/or LM who underwent PI-DWI and EPICS-DWI. Two radiologists assessed the DWI images and assigned confidence scores for hepatic lesions conspicuity using 4-point scale. One of the radiologists additionally calculated the contrast-to-noise ratio (CNR) and measured ADC value of the hepatic lesions. The conspicuity, CNR, and ADC values were compared between the two sequences. A receiver operating characteristic (ROC) analysis was performed to assess the diagnostic abilities of the two sequences for differentiating HHs and LMs. RESULTS: The conspicuity of LMs was better in EPICS-DWI than in PI-DWI (P < .05 in both radiologists). The CNR of LMs was higher in EPICS-DWI than in PI-DWI (P = .008). No difference was found in the CNR of HHs (P = .52), ADC values for HHs (P = .79), and LMs (P = .29) between the two sequences. To differentiate between HHs and LMs, the cutoff ADC values were 1.38 × 10-3 mm2/s in PI-DWI and 1.37 × 10-3 mm2/s in EPICS-DWI. The area under the ROC curve (P = .86), sensitivity (P > .99), and specificity (P > .99) did not vary. CONCLUSIONS: The LMs were more visible in EPICS-DWI than in PI-DWI. However, the cutoff ADC values and diagnostic abilities for differentiating HHs and LMs were almost comparable between the two sequences.

Deep-learning image reconstruction for 80-kVp pancreatic CT protocol: Comparison of image quality and pancreatic ductal adenocarcinoma visibility with hybrid-iterative reconstruction.

PURPOSE: To evaluate the image quality and visibility of pancreatic ductal adenocarcinoma (PDAC) in 80-kVp pancreatic CT protocol and compare them between hybrid-iterative reconstruction (IR) and deep-learning image reconstruction (DLIR) algorithms. METHOD: A total of 56 patients who underwent 80-kVp pancreatic protocol CT for pancreatic disease evaluation from January 2022 to July 2022 were included in this retrospective study. Among them, 20 PDACs were observed. The CT raw data were reconstructed using 40% adaptive statistical IR-Veo (hybrid-IR group) and DLIR at medium- and high-strength levels (DLIR-M and DLIR-H groups, respectively). The CT attenuation of the abdominal aorta, pancreas, and PDAC (if present) at the pancreatic phase and those of the portal vein and liver at the portal venous phase; background noise; signal-to-noise ratio (SNR) of these anatomical structures; and tumor-to-pancreas contrast-to-noise ratio (CNR) were calculated. The confidence scores for the image noise, overall image quality, and visibility of PDAC were qualitatively assigned using a five-point scale. Quantitative and qualitative parameters were compared among the three groups using Friedman test. RESULTS: The CT attenuation of all anatomical structures were comparable among the three groups (P = .26-.86), except that of the pancreas (P = .001). Background noise was lower (P <.001) and SNRs (P <.001) and tumor-to-pancreas CNR (P <.001) were higher in the DLIR-H group than those in the other two groups. The image noise, overall image quality, and visibility of PDAC were better in the DLIR-H group than in the other two groups (P <.001-.003). CONCLUSION: In 80-kVp pancreatic CT protocol, DLIR at a high-strength level improved image quality and visibility of PDAC.

MRI-Based Tumor Necrosis Depiction in Pancreatic Ductal Adenocarcinoma: Can It Predict Tumor Aggressiveness?

The purpose of this study was to investigate whether tumor necrosis depicted on contrast-enhanced abdominal MRI can predict tumor aggressiveness in pancreatic ductal adenocarcinoma (PDAC). In this retrospective analysis, we included 71 patients with pathology-proven PDAC who underwent contrast-enhanced MRI from 2006 to 2020. Assessment for the presence/absence of imaging detected necrosis was performed on T2-weighted and contrast-enhanced T1-weighted images. Primary tumor characteristics, regional lymphadenopathy, metastases, stage, and overall survival were analyzed. Fisher's exact and Mann-Whitney U tests were used for statistical analysis. Of the 72 primary tumors, necrosis was identified on MRI in 58.3% (42/72). Necrotic PDACs were larger (44.6 vs. 34.5 mm, p = 0.0016), had higher rates of regional lymphadenopathy (69.0% vs. 26.7%, p = 0.0007), and more frequent metastases (78.6% vs. 40.0%, p = 0.0010) than those without MRI-evident necrosis. A non-statistically significant reduction in median overall survival was observed in patients with versus without MRI-evident necrosis (15.8 vs. 38.0 months, p = 0.23). PDAC tumor necrosis depicted on MRI was associated with larger tumors and higher frequency of regional lymphadenopathy and metastases.