Investigation of abdominal artery delineation by photon-counting detector CT.

OBJECTIVES: To evaluate the ability of 50-keV virtual monoenergetic images (VMI) to depict abdominal arteries in abdominal CT angiography (CTA) compared with 70-keV VMI with photon-counting detector CT (PCD-CT). METHODS: Fifty consecutive patients who underwent multiphase abdominal scans between March and April 2023 were included. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were quantitatively assessed for the abdominal aorta (AA), celiac artery (CeA), superior mesenteric artery (SMA), renal artery (RA), and right hepatic artery (RHA) at both 50- and 70-keV VMI. In addition, 3D images from CTA were analyzed to measure arterial lengths and evaluate the visualization of distal branches. RESULTS: Significantly higher SNR and CNR were observed at 50-keV compared to 70-keV VMI for all arteries: AA (36.54 and 48.28 vs. 25.70 and 28.46), CeA (22.39 and 48.38 vs. 19.09 and 29.15), SMA (23.34 and 49.34 vs. 19.67 and 29.71), RA (22.88 and 48.84 vs. 20.15 and 29.41), and RHA (14.38 and 44.41 vs. 13.45 and 27.18), all p < 0.05. Arterial lengths were also significantly longer at 50-keV: RHA (192.6 vs. 180.3 mm), SMA (230.9 vs. 216.5 mm), and RA (95.9 vs. 92.0 mm), all p < 0.001. CONCLUSION: In abdominal CTA with PCD-CT, 50-keV VMI demonstrated superior quantitative image quality compared to 70-keV VMI. In addition, 50-keV VMI 3D CTA allowed better visualization of abdominal artery branches, highlighting its potential clinical advantage for improved imaging and detailed assessment of abdominal arteries.

Risk stratification of oesophageal squamous cell carcinoma using change in total lesion glycolysis and number of PET-positive lymph nodes.

BACKGROUND: The efficacy of neoadjuvant chemotherapy (NACT) correlates with patient survival in oesophageal squamous cell carcinoma (OSCC), but optimal evaluation of the treatment response based on PET-CT parameters has not been established. METHODS: We analysed 226 OSCC patients who underwent PET-CT before and after NACT followed by surgery. We assessed SUVmax, metabolic tumour volume (MTV), and total lesion glycolysis (TLG) for the primary tumour and the number of PET-positive lymph nodes before and after NACT to predict patient survival. RESULTS: In a stepwise analysis, we defined 60%, 80%, and 80% as the optimal cut-off values for SUVmax, MTV, and TLG reduction, respectively, to distinguish responders and non-responders to NACT. In the ROC analysis, the TLG reduction rate was the best predictor of recurrence among PET-CT parameters. The TLG responders achieved significantly more favourable prognoses than non-responders (2-year progression-free survival [PFS] rate: 64.1% vs. 38.5%; P = 0.0001). TLG reduction rate (HR 2.58; 95% CI 1.16-5.73) and the number of PET-positive lymph nodes after NACT (HR 1.79; 95% CI 1.04-3.08) were significant independent prognostic factors. CONCLUSIONS: TLG reduction is the best predictor of prognosis. Preoperative PET-CT evaluation of both the primary tumour and lymph nodes could accurately stratify risk in OSCC patients.

Image Quality and Lesion Detectability of Pancreatic Phase Thin-Slice Computed Tomography Images With a Deep Learning-Based Reconstruction Algorithm.

OBJECTIVE: To evaluate the image quality and lesion detectability of pancreatic phase thin-slice computed tomography (CT) images reconstructed with a deep learning-based reconstruction (DLR) algorithm compared with filtered-back projection (FBP) and hybrid iterative reconstruction (IR) algorithms. METHODS: Fifty-three patients who underwent dynamic contrast-enhanced CT including pancreatic phase were enrolled in this retrospective study. Pancreatic phase thin-slice (0.625 mm) images were reconstructed with each FBP, hybrid IR, and DLR. Objective image quality and signal-to-noise ratio of the pancreatic parenchyma, and contrast-to-noise ratio of pancreatic lesions were compared between the 3 reconstruction algorithms. Two radiologists independently assessed the image quality of all images. The diagnostic performance for the detection of pancreatic lesions was compared among the reconstruction algorithms using jackknife alternative free-response receiver operating characteristic analysis. RESULTS: Deep learning-based reconstruction resulted in significantly lower image noise and higher signal-to-noise ratio and contrast-to-noise ratio than hybrid IR and FBP ( P < 0.001). Deep learning-based reconstruction also yielded significantly higher visual scores than hybrid IR and FBP ( P < 0.01). The diagnostic performance of DLR for detecting pancreatic lesions was highest for both readers, although a significant difference was found only between DLR and FBP in one reader ( P = 0.02). CONCLUSIONS: Deep learning-based reconstruction showed improved objective and subjective image quality of pancreatic phase thin-slice CT relative to other reconstruction algorithms and has potential for improving lesion detectability.

Diagnostic accuracy of MRI for evaluating myometrial invasion in endometrial cancer: a comparison of MUSE-DWI, rFOV-DWI, and DCE-MRI.

OBJECTIVES: To compare the image quality of high-resolution diffusion-weighted imaging (DWI) using multiplexed sensitivity encoding (MUSE) versus reduced field-of-view (rFOV) techniques in endometrial cancer (EC) and to compare the diagnostic performance of these techniques with that of dynamic contrast-enhanced (DCE) MRI for assessing myometrial invasion of EC. METHODS: MUSE-DWI and rFOV-DWI were obtained preoperatively in 58 women with EC. Three radiologists assessed the image quality of MUSE-DWI and rFOV-DWI. For 55 women who underwent DCE-MRI, the same radiologists assessed the superficial and deep myometrial invasion using MUSE-DWI, rFOV-DWI, and DCE-MRI. Qualitative scores were compared using the Wilcoxon signed-rank test. Receiver operating characteristic analysis was performed to compare the diagnostic performance. RESULTS: Artifacts, sharpness, lesion conspicuity, and overall quality were significantly better with MUSE-DWI than with rFOV-DWI (p < 0.05). The area under the curve (AUC) of MUSE-DWI, rFOV-DWI, and DCE-MRI for the assessment of myometrial invasion were not significantly different except for significantly higher AUC of MUSE-DWI than that of DCE-MRI for superficial myometrial invasion (0.76 for MUSE-DWI and 0.64 for DCE-MRI, p = 0.049) and for deep myometrial invasion (0.92 for MUSE-DWI and 0.80 for DCE-MRI, p = 0.022) in one observer, and that of rFOV-DWI for deep myometrial invasion in another observer (0.96 for MUSE-DWI and 0.89 for rFOV-MRI, p = 0.048). CONCLUSION: MUSE-DWI exhibits better image quality than rFOV-DWI. MUSE-DWI and rFOV-DWI shows almost equivalent diagnostic performance compared to DCE-MRI for assessing superficial and deep myometrial invasion in EC although MUSE-DWI may be helpful for some radiologists.

Performance of oral HPV DNA, oral HPV mRNA and circulating tumor HPV DNA in the detection of HPV-related oropharyngeal cancer and cancer of unknown primary.

A biomarker that is useful for the detection of human papillomavirus (HPV)-related oropharyngeal cancer (OPC) and cancer of unknown primary (CUP) is indispensable. We evaluated the diagnostic performance of HPV DNA and mRNA in oral gargle samples and circulating tumor HPV16 DNA (ctHPV16DNA) in blood samples. Oral HPV DNA and mRNA were analyzed using commercially available HPV assays of the GENOSEARCH HPV31 and Aptima, respectively. ctHPV16DNA was analyzed using in-house droplet digital polymerase chain reaction. Seventy-four patients with OPC and eight patients with CUP were included. The sensitivity and specificity of oral HPV DNA, oral HPV mRNA, and ctHPV16DNA were 82% (95% confidence interval [CI] = 66-92) and 100% (95% CI = 88-100), 85% (95% CI = 69-94) and 94% (95% CI = 73-100), and 93% (95% CI = 81-99) and 97% (95% CI = 84-100), respectively, for HPV16-related OPC, while those were 20% (95% CI = 1-72) and 100% (95% CI = 3-100), 0% (95% CI = 0-52) and 100% (95% CI = 3-100), and 100% (95% CI = 54-100) and 100% (95% CI = 16-100), respectively, for HPV16-related CUP. The sensitivity of ctHPV16DNA for HPV16-related OPC was higher than that of oral biomarkers, though the difference was not statistically significant. ctHPV16DNA remarkably correlated with the anatomic extent of disease, total metabolic tumor volume and HPV16 copy number per tumor genome in patients with HPV16-related OPC/CUP, whereas oral biomarkers did not. In conclusion, ctHPV16DNA is a potentially promising biomarker for HPV16-related OPC, while further studies are required for HPV16-related CUP.

MRI of Borderline Epithelial Ovarian Tumors: Pathologic Correlation and Diagnostic Challenges.

Borderline epithelial ovarian tumors are a distinct pathologic entity characterized by increased epithelial proliferation and nuclear atypia, but without frank stromal invasion. Borderline tumor (BT) is now considered to represent an intermediate phase in the stepwise progression from benign to malignant ovarian epithelial tumor. Since BTs commonly manifest at early stages in women of reproductive age and are associated with a good prognosis, making the correct diagnosis is important in determining whether a patient is a candidate for fertility-sparing surgery. There are six histologic BT subtypes (serous, mucinous, seromucinous, endometrioid, clear cell, and Brenner), and each has different MRI features, reflecting their unique histologic architectures. Radiologists should be aware of the MRI features that can suggest BTs. These features include a hyperintense papillary architecture with hypointense internal branching, which can be observed with serous and seromucinous BTs on T2-weighted images; aggregates of microcysts that have hypointensity on T2-weighted images and reticular enhancement on contrast-enhanced T2-weighted images, which can be seen with mucinous BTs; and moderately high signal intensity on diffusion-weighted images along with relatively high apparent diffusion coefficient values, which can be observed regardless of the histologic subtype. Nevertheless, because the imaging features of BTs overlap with those of many benign lesions (eg, cystadenoma and cystadenofibroma, decidualized endometriosis, and polypoid endometriosis) and malignant tumors (ovarian cancers and metastases), histologic confirmation is required for the final diagnosis. Special emphasis is placed on the MRI features of BTs, pathologic correlation, and the challenges related to diagnosis. ©RSNA, 2022.

Circulating tumor HPV DNA complements PET-CT in guiding management after radiotherapy in HPV-related squamous cell carcinoma of the head and neck.

Positron emission tomography and computed tomography (PET-CT) is widely used to assess the response to radiotherapy. However, the ability of PET-CT to predict treatment failure in human papillomavirus (HPV)-related squamous cell carcinoma of the head and neck (HNSCC) is unsatisfactory. We quantified circulating tumor HPV type16 DNA (ctHPV16DNA) using optimized droplet digital PCR in 35 patients with HPV16-related HNSCC, who received radiotherapy with or without chemotherapy, and prospectively correlated ctHPV16DNA and metabolic response with treatment failure. After a median follow-up of 21 months, ctHPV16DNA and PET-CT had similar negative predictive values (89.7% vs 84.0%), whereas the positive predictive value was much higher in ctHPV16DNA than in PET-CT (100% vs 50.0%). Notably, six patients who had detectable posttreatment ctHPV16DNA all had treatment failure irrespective of metabolic response, whereas none of five patients who had partial metabolic response without detectable posttreatment ctHPV16DNA had treatment failure. The risk of treatment failure was high in patients who had incomplete metabolic response with detectable posttreatment ctHPV16DNA (hazard ratio [HR], 138.8; 95% confidence interval [CI], 15.5-3366.4; P < .0001) and intermediate in patients who had discordant results between metabolic response and posttreatment ctHPV16DNA (HR, 4.7; 95% CI, 0.8-36.2, P = .09) as compared with patients who had complete metabolic response without detectable posttreatment ctHPV16DNA. One-year event-free survival rates of each risk group were 0%, 88% (95% CI, 46-98) and 95% (95% CI, 72-99), respectively (P < .0001). In conclusion, posttreatment ctHPV16DNA complements PET-CT and helps guide decisions managing patients with HPV16-related HNSCC after radiotherapy.

Peritumoral Lymphatic Vessels Associated with Resistance to Neoadjuvant Chemotherapy and Unfavorable Survival in Esophageal Cancer.

BACKGROUND: Peri- or intra-tumor lymphangiogenesis is induced in several types of cancer. However, the significance of peritumoral lymphatic vessels (LVs) in esophageal cancer (EC) remains to be clarified. METHODS: This study included 162 eligible EC patients with or without neoadjuvant chemotherapy (NAC). The numbers of non-tumoral and peritumoral LVs were counted in resected specimens based on podoplanin immunostaining. The association between peritumoral LV number and clinicopathologic parameters, including tumor heterogeneity as measured by positron emission tomography, NAC response, and patient survival were analyzed. RESULTS: In non-NAC patients, the number of peritumoral LVs was highest in the lamina propria mucosa (LPM), followed by non-tumoral LVs in the LPM, peritumoral LVs in the submucosa (SM), and non-tumoral LVs in the SM. The patients with a low number of peritumoral LVs in the LPM versus those with a high number constituted a larger fraction of the NAC patients (67.8% vs. 50.0%; P = 0.022) and had a poorer pathologic response to NAC (grades 0-1a: 68.8% vs. 47.2%; P = 0.035), as well as greater tumor heterogeneity and worse survival (5-year overall survival: 50.6% vs. 72.8%; P = 0.0097). The number of peritumoral LVs in the LPM was identified as an independent prognostic factor with the highest hazard ratio (HR) of overall survival (HR 2.06; P = 0.0049) in the multivariate analysis. CONCLUSION: For EC patients, peritumoral LVs in the LPM layer are associated with tumor heterogeneity, response to NAC, and unfavorable survival.

Metabolic Tumor Volume Change Predicts Long-term Survival and Histological Response to Preoperative Chemotherapy in Locally Advanced Esophageal Cancer.

OBJECTIVE: Here, we assess the ability of metabolic tumor volume (MTV) as measured by F-fluorodeoxyglucose-positron emission tomography/computed tomography (F-FDG PET/CT) to evaluate neoadjuvant chemotherapy response for patients with locally advanced esophageal cancer (EC). BACKGROUND: Optimal methods to evaluate treatment response for EC patients have not yet been established. Although previous studies have reported the value of standardized uptake value (SUV), the accuracy of predicting histological response or long-term survival in EC is limited. METHODS: In all, 102 EC patients without distant metastasis who underwent F-FDG PET/CT both before and after the preoperative chemotherapy series were analyzed. RESULTS: The median primary tumor MTV values before and after preoperative chemotherapy were 22.55 (range 0.4-183.1) and 2.75 (0-52.9), respectively, and the median MVT reduction rate was 86.5%. We found the most significant difference in survival between PET responders and nonresponders with a cut-off value of 60% MTV reduction, using a 10% stepwise cut-off analysis [2-year progression-free survival (PFS): 79.2 vs 44.4%; hazard ratio (HR) 3.397; P < 0.0001). With this cut-off value, histological response (P = 0.0091), tumor location (P = 0.0102), pT (P = 0.0011), and pN (P = 0.0110) were significantly associated with PET response. Univariate analysis of PFS indicated a correlation between PFS and tumor size, cT, decrease of primary lesion by CT, SUVmax reduction rate, MTV reduction rate, pT, pN, and pM. Multivariate analysis further identified pM (HR 3.063; P = 0.0279) and MTV reduction rate (HR 2.471; P = 0.0263) to be independent prognostic predictors, but not decrease of primary lesion by CT or SUVmax reduction rate. CONCLUSION: MTV change is clinically useful in predicting both long-term survival and histological response to preoperative chemotherapy in EC patients, after determining the optimal cut-off value based on survival analysis.

Volumetric and texture analysis on FDG PET in evaluating and predicting treatment response and recurrence after chemotherapy in follicular lymphoma.

PURPOSE: The purpose of this study was to determine if quantitative SUV-related, volumetric FDG PET parameters, and texture features (SPs, VPs, and TFs, respectively) were useful to evaluate and predict response and recurrence after chemotherapy in follicular lymphoma (FL). METHODS: Pre- and posttreatment FDG PET examinations in 45 FL patients were analyzed retrospectively. In addition to SPs in the representative lesion, metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were calculated as VPs for the representative and whole-body lesions. Six TFs were calculated in the pretreatment representative lesion. Response results with reduction of SPs or VPs after treatment (Δ) were compared to the Lugano classification based on visual assessment. SPs, VPs, and Δ of them as well as TFs were also evaluated if they allow prediction of response and recurrence after chemotherapy. RESULTS: Quantitative assessment with SPs and VPs provided 89% and 93-96% concordant results, respectively, with Lugano classification. Among pretreatment PET parameters, low gray-level zone emphasis (LGZE) in TFs solely showed statistical significance to predict complete response. All of posttreatment and Δ of SPs and VPs were considered as the predictors of progression free survival in the univariate Cox regression analysis, but none of them was the predictor in the multivariate analysis. CONCLUSION: This study demonstrated that quantitative PET parameters were applicable to evaluate treatment response in FL. Texture analysis showed promise in predicting treatment response. Although posttreatment and Δ of PET parameters were the candidates, all of them proved to have limited value in predicting recurrence after chemotherapy.

Phantom Study of In-Stent Restenosis at High-Spatial-Resolution CT.

Purpose To examine the diagnostic performance of high-spatial-resolution (HSR) CT with 0.25-mm section thickness for evaluating renal artery in-stent restenosis. Materials and Methods A 0.05-mm wire phantom and vessel phantoms with renal stents with in-stent stenotic sections of varying diameters were scanned with both an HSR CT scanner equipped with 160-section multi-detector rows (0.25-mm section thickness) and a conventional CT scanner. The wire phantom was used to analyze modulation transfer function (MTF). With the vessel phantoms, the error rates were calculated as the absolute difference between the measured diameters and true diameters divided by the true diameters at the narrowing sections. For qualitative evaluation, overall image quality and diagnostic accuracy for evaluating stenosis in three stages were assessed by two radiologists. Statistical analyses included the paired t test, Wilcoxon signed-rank test, and McNemar test. Results HSR CT achieved 24.3 line pairs per centimeter ± 0.5 (standard deviation) and 29.1 line pairs per centimeter ± 0.4 at 10% and 2% MTF, respectively; and conventional CT was 12.5 line pairs per centimeter ± 0.1 and 14.3 line pairs per centimeter ± 0.1 at 10% and 2% MTF, respectively. The mean error rate of the measured diameter at HSR CT (8.0% ± 5.8) was significantly lower than that at at conventional CT (16.9% ± 9.3; P < .001). Image quality at HSR CT was significantly better than that at conventional CT (P < .001), but HSR CT was not significantly superior to conventional CT in terms of diagnostic accuracy. Conclusion Compared with conventional CT, high-spatial-resolution CT achieved spatial resolutions of up to 29 line pairs per centimeter at 2% modulation transfer function and yielded improved measurement accuracy for the evaluation of in-stent restenosis in a phantom study of renal artery stents. Published under a CC BY 4.0 license.

Assessment of Myometrial Invasion in Premenopausal Grade 1 Endometrial Carcinoma: Is Magnetic Resonance Imaging a Reliable Tool in Selecting Patients for Fertility-Preserving Therapy?

OBJECTIVES: The aim of this study was to evaluate the diagnostic ability of magnetic resonance imaging (MRI) in premenopausal women with G1 endometrial carcinoma. METHODS: Twenty-six patients underwent T2W, diffusion weighted, and dynamic contrast-enhanced 3-T MRI. The degree of myometrial invasion was pathologically classified into no invasion, shallow (3 mm or less), and more. Two radiologists assessed myometrial invasion on MRI. Diagnostic accuracy, sensitivity, specificity, positive and negative predictive values, AUC, and interobserver agreement were analyzed. RESULTS: For assessing myometrial invasion, mean accuracy, sensitivity, specificity, positive predictive values, negative predictive values, and AUC, respectively, were as follows: 63%, 42%, 85%, 79%, 47%, and 0.75. Mean interobserver agreement was fair (k = 0.36). Shallow invasions were underestimated as no invasion on MRI in all 6 cases. CONCLUSIONS: Magnetic resonance imaging produced false-negative result on half of patients. The misjudgments tended to happen in patients with shallow invasion.

Value of 18F-FDG PET/CT in discrimination between indolent and aggressive non-Hodgkin's lymphoma: A study of 328 patients.

OBJECTIVE: Non-Hodgkin's lymphoma (NHL) cases with inconclusive biopsy findings are not infrequently referred for fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). We searched for maximum standardized uptake value (SUVmax) cut-off values that could discriminate between indolent and aggressive NHL in conventional non-time of flight (non-TOF) 18F-FDG PET/CT and TOF 18F-FDG PET/CT. SUBJECTS AND METHODS: Retrospectively, 328 patients were selected by the following inclusion criteria: biopsy-proven NHL with no more than one histopathological type; new cases with less than 90 days between obtaining biopsy and 18F-FDG PET/CT scanning; recurrent cases with time interval more than six months since the last therapy with no history of transformation; and blood glucose less than 150mg/dL. Two hundred forty six (246) selected patients were scanned with non-TOF PET/CT, and 82 patients were scanned with TOF 18F-FDG PET/CT. RESULTS: The SUVmax of NHL tends to be higher in TOF 18F-FDG PET/CT than non-TOF 18F-FDG PET/CT. New aggressive NHL had significantly higher SUVmax than new indolent NHL in both, non-TOF 18F-FDG PET/CT (13.6±7.7g/mL vs. 5.3±3.4g/mL, P<0.0001) and TOF 18F-FDG PET/CT (20.5±9.8g/mL vs. 6.6±4.7g/mL, P<0.0001). A receiver operating characteristic curve analysis for new cases in non-TOF 18F-FDG PET/CT (n=204), demonstrated SUVmax of 10g/mL as the most balanced cut-off between aggressive and indolent NHL, with the area under the curve (AUC) of 86%, specificity of 94%, and sensitivity of 71%. While SUVmax of 13g/mL was the most balanced cut-off for new cases in TOF 18F-FDG PET/CT (n=57), with AUC of 91%, specificity of 95.5%, and sensitivity of 77%. CONCLUSION: Both SUVmax>10g/mL in non-TOF 18F-FDG PET/CT and >13g/mL in TOF 18F-FDG PET/CT were highly suggestive of an aggressive nature of NHL, while there was an overlap between indolent and aggressive NHL in the lower SUVmax levels.

Metabolic tumor volume of primary tumor predicts survival better than T classification in the larynx preservation approach.

We aimed to determine whether pretreatment metabolic tumor volume of the primary tumor (T-MTV) or T classification would be a better predictor of laryngectomy-free survival (LFS) and overall survival (OS) after chemoradiotherapy in patients with locally advanced laryngeal or hypopharyngeal cancer requiring total laryngectomy. We analyzed 85 patients using a Cox proportional hazards model and evaluated its usefulness by Akaike's information criterion. A T-MTV cut-off value was determined by time-dependent receiver operating characteristic curve analysis. Interobserver reliability for measuring T-MTV was estimated by the intraclass correlation coefficient (ICC). After adjustment for covariables, T-MTV, irrespective of whether a continuous or dichotomized variable, and T classification remained independent predictors of LFS and OS. Large T-MTV (>28.7 mL) was associated with inferior LFS (hazard ratio [HR], 4.16; 95% confidence interval [CI], 1.97-8.70; P = 0.0003) and inferior OS (HR, 3.18; 95% CI, 1.47-6.69; P = 0.004) compared with small T-MTV (≤28.7 mL). The T-MTV model outperformed the T classification model in predicting LFS and OS (P = 0.007 and 0.01, respectively). Three-year LFS and OS rates for patients with small versus large T-MTV were 68% vs 9% (P < 0.0001) and 77% vs 25% (P < 0.0001), respectively, whereas those for patients with T2-T3 versus T4a were 61% vs 31% (P = 0.003) and 71% vs 48% (P = 0.10), respectively. ICC was 0.99 (95% CI, 0.99-1.00). Given the excellent interobserver reliability, T-MTV is better than T classification to identify patients who would benefit from the larynx preservation approach.

Preoperative staging of endometrial cancer using reduced field-of-view diffusion-weighted imaging: a preliminary study.

OBJECTIVES: To compare the image quality and diagnostic performance of reduced field-of-view (rFOV) versus conventional full field-of-view (fFOV) diffusion-weighted (DW) imaging of endometrial cancer. METHODS: Fifty women with endometrial cancer underwent preoperative rFOV and fFOV DW imaging. Two radiologists compared the image qualities of both techniques, and five radiologists assessed superficial and deep myometrial invasion using both techniques. The statistical analysis included the Wilcoxon signed-rank test and paired t-test for comparisons of image quality and mean diagnostic values. RESULTS: Distortion, tumour delineation, and overall image quality were significantly better with rFOV DW imaging, compared to fFOV DW imaging (P < 0.05); however, the former was inferior in noise (P < 0.05). Regarding superficial invasion, the mean accuracies of the techniques did not differ statistically (rFOV, 58.0% versus fFOV, 56.0%; P = 0.30). Regarding deep myometrial invasion, rFOV DW imaging yielded significantly better mean accuracy, specificity, and positive predictive values (88.4%, 97.8%, and 91.7%, respectively), compared with fFOV DW imaging (84.8%, 94.1%, and 77.4%, respectively; P = 0.009, 0.005, and 0.011, respectively). CONCLUSIONS: Compared with fFOV DW imaging, rFOV DW imaging yielded less distortion, improved image quality and, consequently, better diagnostic performance for deep myometrial invasion of endometrial cancer. KEY POINTS: • rFOV DWI yields better assessment of deep myometrial invasion in endometrial cancer. • rFOV DWI could not sufficiently evaluate superficial invasion in endometrial cancer. • Distortion, tumour delineation, and overall image quality were improved with rFOV DWI.

[A Case Report of Curative Surgery for Pancreatic Ductal Adenocarcinoma with Peritoneal Dissemination after Gemcitabine Chemotherapy].

A 70-year-old man was diagnosed with pancreatic ductal adenocarcinoma(PDAC)with peritoneal dissemination and received systemic chemotherapy of gemcitabine(GEM)plus nab-paclitaxel. Since the patient could not continue the regimen due to an adverse event of liver dysfunction, he was administered GEM alone except for the first administration. GEM monotherapy resulted in remarkable anti-tumor effects with a distinct decrease of both tumor markers and size. Peritoneal metastases were not detected in images after 12 courses of the GEM regimen, and the vanished tumor metastasis in images was maintained until 16 courses were administered. After the laparoscopic examination proved no peritoneal metastasis, we performed curative surgery. The presence of peritoneal metastasis of PDAC indicated that it was at a lethal stage; however, a few cases were reported as receiving curative surgery after chemotherapy with modest long-term survival. We herein report a rare case of curative surgery following chemotherapy with GEM alone for unresectable PDAC accompanied with peritoneal dissemination.

[Creation and Evaluation of Educational Programs for Additional Delayed Scan of FDG-PET/CT].

Generally, FDG-PET/CT image is acquired at the 60th minute after tracer administration. Depending on the clinical case, additional delayed scans may be useful. However, it is difficult to judge whether additional delayed scan is useful or not. The purposes of this study were creation and evaluation of educational programs to help radiological technologists to decide the usefulness of additional delayed scan of FDG-PET/CT. METHODS: Educational programs consisted of the instructional materials and the judgment test of clinical cases. The instructional materials provided the valuable findings for differentiation between uptake in the wall of the colon and colon content, distinction between uptake in the lymph node and urinary tract, and evaluation of malignancy. The judgment test of clinical cases consisted of 10 cases selected by a nuclear medicine physician (for 5 of that cases additional delayed scan was decided to be useful). Five experienced technologists and five inexperienced technologists scored the volubility of additional delayed scan pre- and post-training using the instructional materials (the full marks of score is 5). RESULTS: After the educational programs using the instructional materials, the score was improved with the significant difference in both experienced (pre: 3.6±1.4, post: 4.0±1.2) and inexperienced (pre: 2.8±1.5, post: 3.7±1.5) groups (p<0.05). CONCLUSION: According to the educational programs, technologist might be able to decide whether the additional delayed scan is useful or not. The successful results of this study may improve the interpretation or reduce the total exposure dose of the PET/CT scan.