Yuji Nakamoto - Academia.edu (original) (raw)

Papers by Yuji Nakamoto

Diagnostics, 2021

Dedicated breast positron emission tomography (dbPET) is a new diagnostic imaging modality recent... more Dedicated breast positron emission tomography (dbPET) is a new diagnostic imaging modality recently used in clinical practice for the detection of breast cancer and the assessment of tumor biology. dbPET has higher spatial resolution than that of conventional whole body PET systems, allowing recognition of detailed morphological attributes of radiotracer accumulation within the breast. 18F-fluorodeoxyglucose (18F-FDG) accumulation in the breast may be due to benign or malignant entities, and recent studies suggest that morphology characterization of 18F-FDG uptake could aid in estimating the probability of malignancy. However, across the world, there are many descriptors of breast 18F-FDG uptake, limiting comparisons between studies. In this article, we propose a lexicon for breast radiotracer uptake to standardize description and reporting of image findings on dbPET, consisting of terms for image quality, radiotracer fibroglandular uptake, breast lesion uptake.

Molecular Imaging and Biology, 2021

Purpose: Flexible positron emission tomography (fxPET) employing a non-local means reconstruction... more Purpose: Flexible positron emission tomography (fxPET) employing a non-local means reconstruction algorithm, was designed to fit existing magnetic resonance imaging (MRI) systems. We aimed to compare the qualitative and quantitative performance of fxPET among fxPET with MR-based attenuation correction (MRAC), fxPET with CT-based attenuation correction (CTAC) using CT as a part of WB PET/CT, and whole-body (WB) PET/CT. Procedures: Sixteen patients with suspected head and neck cancer underwent 2-deoxy-2-[ 18 F]fluoro-D-glucose WB PET/CT scans, followed by fxPET and 3T MRI scans. Phantom data were compared among the three datasets. For registration accuracy, we measured the distance between the center of the tumor determined by fxPET and that in MRI. We compared image quality, detection rates and quantitative values including maximal standardized uptake value (SUVmax), metabolic tumor volume (MTV), total lesion glycolysis (TLG) and tumor-to-muscle ratio (TMR) among the three datasets. A Self-archived copy in Kyoto University Research Information Repository https://repository.kulib.kyoto-u.ac.jp Results: The phantom data in fxPET, except the percent contrast recoveries of 17-mm and 22-mm hot spheres, were inferior to those in WB PET/CT. The mean registration accuracy was 4.4 mm between fxPET using MRAC and MRI. The image quality was comparable between two fxPET datasets, but significantly inferior to WB PET/CT (p < 0.0001). In contrast, detection rates were comparable among the three datasets. SUVmax was significantly higher, and MTV and TLG were significantly lower in the two fxPET datasets compared with the WB PET/CT dataset (p < 0.005). There were no significant differences in SUVmax, MTV and TLG between the two fxPET datasets, or in TMR among the three datasets. All quantitative values had significantly positive correlations. Conclusions: Compared with WB PET/CT, the phantom data and image quality were inferior in fxPET. However, the results of the detection rates and quantitative values suggested the clinical feasibility of fxPET.

Journal of Nuclear Medicine, 2017

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Journal of translational medicine, Jan 11, 2018

Surgical resection remains the mainstay of curative treatment for intrahepatic cholangiocarcinoma... more Surgical resection remains the mainstay of curative treatment for intrahepatic cholangiocarcinoma (ICC). Prognosis after surgery is unsatisfactory despite improvements in treatment and post-operative clinical management. Despite developments in the molecular profiling of ICC, the preoperative prediction of prognosis remains a challenge. This study aimed to identify clinical prognostic indicators by investigating the molecular profiles of ICC and evaluating the preoperative imaging data of F-fluorodeoxyglucose positron emission tomography (F-FDG-PET). A retrospective analysis was performed on 50 consecutive patients with ICC who underwent curative hepatectomy after F-FDG-PET examination. To evaluate the molecular profiles of ICC, KRAS mutation status was assessed in resected specimens. For the assessment of glucose uptake, we observed the expression of glucose transporter-1 (GLUT-1) by immunohistochemistry. The data of F-FDG-PET were re-evaluated as follows: maximum standardized upta...

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, Jan 23, 2016

This study evaluated the clinical significance of (18)F-fluorodeoxyglucose-positron emission tomo... more This study evaluated the clinical significance of (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in patients with interstitial lung disease (ILD), by investigating the relationships between FDG-PET/CT parameters and clinical indicators, and by evaluating the prognostic implications of FDG-PET/CT results. Ninety patients (51 males, 39 females; mean age, 55.4 years; range, 26-78 years) with ILD who underwent FDG-PET/CT were retrospectively analyzed. SUVmean was defined as the mean standardized uptake value (SUV) of the less-affected lung field, SUVTF as adjusted SUVmean using tissue fraction, and CTmean as the mean attenuation of the corresponding region of interest on high resolution CT. SUVmean, SUVTF, and CTmean were compared in the 90 ILD patients and in 15 age- and gender-matched controls. Correlations of SUVmax, SUVmean, SUVTF, and CTmean with clinical indicators, including estimated percentage of forced vital capacity (%FVC), estimated pe...

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 2015

A number of studies have shown that KRAS mutations in colorectal cancer (CRC) result in the lack ... more A number of studies have shown that KRAS mutations in colorectal cancer (CRC) result in the lack of response to anti-epidermal growth factor receptor (EGFR)-based therapy; thus, KRAS mutational testing has been incorporated into routine clinical practice. However, one limitation of this test is the heterogeneity of KRAS status, which can either be intratumoral heterogeneity within an individual primary CRC, or discordant KRAS status between a primary CRC and its corresponding metastases. We previously reported that fluorodeoxyglucose (FDG) accumulation was significantly higher in primary CRCs with mutated KRAS than in those with wild-type KRAS. However, the clinical utility of the previous report has been limited because endoscopic biopsy for testing KRAS status is safe and feasible only in primary CRC. The purpose of this study was to investigate whether KRAS status is associated with FDG accumulation in metastatic CRC, and whether FDG-Positron emission tomography/computed tomograp...

Annals of nuclear medicine, Jan 18, 2015

Positron emission tomography (PET)/computed tomography (CT) using (68)Ga-labeled 1,4,7,10-tetraaz... more Positron emission tomography (PET)/computed tomography (CT) using (68)Ga-labeled 1,4,7,10-tetraazacyclododecane-N,N',N″,N‴-tetraacetic acid-D-Phe(1)-Tyr(3)-octreotide (DOTATOC) has been used to detect neuroendocrine tumors (NETs). The purpose of this study was to investigate the clinical efficacy of DOTATOC-PET/CT for detecting clinically suspected NETs when conventional imaging modalities were negative or inconclusive, in terms of additional value. A total of 46 patients were analyzed retrospectively. Among them, 14 patients underwent a DOTATOC-PET/CT scan for detecting unknown primary tumors after histopathological confirmation of a NET at metastatic sites (group A): 7 patients for detecting metastasis or recurrence after surgery for NET because of their high hormone levels but with no recurrence detected by other imaging modalities (group B); the remaining 25 patients for detecting suspected NETs because their hormone levels were high with no history of histopathologically pr...

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 2002

Recently, some studies have shown that delayed scanning with (18)F-FDG PET may help to differenti... more Recently, some studies have shown that delayed scanning with (18)F-FDG PET may help to differentiate malignant from benign pancreatic lesions. However, no study has evaluated the relationship between temporal changes in (18)F-FDG uptake and expression of hexokinase or glucose transporter. Twenty-one consecutive patients with pancreatic cancer were studied preoperatively by dual-phase (18)F-FDG PET, performed 1 and 2 h after injection of (18)F-FDG. The standardized uptake value (SUV) of the pancreatic cancer was determined, and the retention index (RI) (%) was calculated by subtracting the SUV at 1 h (SUV1) from the SUV at 2 h (SUV2) and dividing by SUV1. The percentages of cells strongly expressing hexokinase type-II (HK-II) and glucose transporter-1 (GLUT-1) were scored on a 5-point scale (1 = 0%-20%, 2 = 20%-40%, 3 = 40%-60%, 4 = 60%-80%, 5 = 80%-100%) by visual analysis of immunohistochemical staining of paraffin sections from the tumor specimens using anti-HK-II and anti-GLUT-1 ...

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 2006

The SET-3000 G/X (clinical tomograph with high resolution and a large axial field of view) is a 3... more The SET-3000 G/X (clinical tomograph with high resolution and a large axial field of view) is a 3-dimensional (3D) (only) dedicated PET camera with germanium oxyorthosilicate (GSO) and bismuth germanate (BGO) scintillators. The main characteristic of the SET-3000 G/X PET scanner is 3D continuous-emission and spiral-transmission (CEST) scanning, yielding a reduction in whole-body scan time. We evaluated the physical performance of the SET-3000 G/X PET scanner with the National Electrical Manufacturers Association (NEMA) NU 2-2001 standard. A GSO 3D emission scanner is combined with a BGO transmission scanner separated axially by a lead shield. In the GSO scanner, small and thick scintillators (2.45 x 5.1 x 30 mm(3)) are arranged in small blocks (23.1 x 52 mm) to achieve high resolution and a high counting rate. The detector ring has a large solid angle with a diameter of 664 mm and an axial coverage of 260 mm (50 rings). The transmission scanner consists of BGO block detectors with a...

AJR. American journal of roentgenology, 2014

The purpose of this study was to assess the diagnostic value of (18)F-FDG PET/CT and MRI in predi... more The purpose of this study was to assess the diagnostic value of (18)F-FDG PET/CT and MRI in predicting the clinicopathologic subtypes of breast cancer. The cases of 89 patients with mass-type invasive breast cancer who underwent FDG PET/CT and MRI before therapy were retrospectively analyzed. Eight imaging variables-maximum standardized uptake value (SUVmax), apparent diffusion coefficient, size, shape, margin, intratumoral enhancement, dynamic kinetics, and high intratumoral signal intensity on T2-weighted images-were compared with results for the pathologic markers Ki-67 antibody, estrogen receptor (ER), progesterone receptor (PR), and ERBB2 (formerly HER2 or HER2/neu). The diagnostic performance of the imaging variables for sub-typing was evaluated, and the predictors of the subtypes were elucidated. Higher SUVmax was significantly associated with a high Ki-67 index (p < 0.0001), ER-negative status (p = 0.0001), and PR-negative status (p = 0.047). Significant correlation was a...

Radiotherapy and Oncology, 2010

Background and Purpose: The purpose was to characterize 18 F-fluorodeoxyglucosepositron emission ... more Background and Purpose: The purpose was to characterize 18 F-fluorodeoxyglucosepositron emission tomography (FDG-PET) findings after stereotactic body radiation therapy (SBRT) for lung cancer. Materials and Methods: This was a retrospective review of 32 FDG-PET scans from 23 patients who underwent SBRT for lung cancer and who showed no evidence of local recurrence. The FDG uptake by lesions was assessed visually using a 3-point scale (0, none or faint; 1, mild; or 2, moderate to intense), and the demarcation (ill-or welldefined) was evaluated. For semi-quantitative analysis, the maximum standardized uptake value (SUVmax) was calculated. Results: Grade 2 intensity was observed in 70, 33, 30, and 0% of PET scans performed <6, 6-12, 12-24, and >24 months, respectively, after SBRT; well-defined demarcation was observed in 80, 33, 40, and 17%, respectively, and the respective means of the SUVmax were 4.9, 2.6, 3.0 and 2.3. The SUVmax was significantly higher for scans performed at <6 months than at 6-12 or >24 months. Conclusions: FDG uptake tended to be intense and well-defined at early times after SBRT, especially within 6 months, and was faint and ill-defined at later periods. Moderate to intense FDG uptake observed soon after SBRT does not always indicate a residual tumour.

Journal of Nuclear Medicine, 2014

The aim of this work was to evaluate the performance characteristics of a newly developed dedicat... more The aim of this work was to evaluate the performance characteristics of a newly developed dedicated breast PET scanner, according to National Electrical Manufacturers Association (NEMA) NU 4-2008 standards. Methods: The dedicated breast PET scanner consists of 4 layers of a 32 • 32 lutetium oxyorthosilicate-based crystal array, a light guide, and a 64-channel position-sensitive photomultiplier tube. The size of a crystal element is 1.44 • 1.44 • 4.5 mm. The detector ring has a large solid angle with a 185-mm aperture and an axial coverage of 155.5 mm. The energy windows at depth of interaction for the first and second layers are 400-800 keV, and those at the third and fourth layers are 100-800 keV. A fixed timing window of 4.5 ns was used for all acquisitions. Spatial resolution, sensitivity, counting rate capabilities, and image quality were evaluated in accordance with NEMA NU 4-2008 standards. Human imaging was performed in addition to the evaluation. Results: Radial, tangential, and axial spatial resolution measured as minimal full width at half maximum approached 1.6, 1.7, and 2.0 mm, respectively, for filtered backprojection reconstruction and 0.8, 0.8, and 0.8 mm, respectively, for dynamic row-action maximum-likelihood algorithm reconstruction. The peak absolute sensitivity of the system was 11.2%. Scatter fraction at the same acquisition settings was 30.1% for the rat-sized phantom. Peak noise-equivalent counting rate and peak true rate for the ratlike phantom was 374 kcps at 25 MBq and 603 kcps at 31 MBq, respectively. In the image-quality phantom study, recovery coefficients and uniformity were 0.04-0.82 and 1.9%, respectively, for standard reconstruction mode and 0.09-0.97 and 4.5%, respectively, for enhanced-resolution mode. Human imaging provided highcontrast images with restricted background noise for standard reconstruction mode and high-resolution images for enhancedresolution mode. Conclusion: The dedicated breast PET scanner has excellent spatial resolution and high sensitivity. The performance of the dedicated breast PET scanner is considered to be reasonable enough to support its use in breast cancer imaging.

Japanese Journal of Clinical Oncology, 2007

Background: Diagnostic guidelines for the use of 2-(fluorine 18) fluoro-2 deoxy-D-glucose (FDG)-p... more Background: Diagnostic guidelines for the use of 2-(fluorine 18) fluoro-2 deoxy-D-glucose (FDG)-positron emission tomography (PET) in cancer screening have yet to be established. We assessed inter-observer variability in screening FDG-PET. Methods: Subjects comprised 40 individuals who underwent FDG-PET and computed tomography (CT) for cancer screening. To assess various patterns of FDG uptakes, three subsets of the cases were selected: 'Cancer', 15 cases with cancer; 'Not malignant', 15 cases with suspected cancer by FDG-PET who were confirmed as cancer-free; and 'Normal', 10 cases without remarkable FDG uptake who were confirmed as cancer-free. A total of 68 lesions made up of malignancy (n ¼ 18), benign (n ¼ 21), and physiological FDG uptake (n ¼ 29) were interpreted by six physicians. Each observer reviewed each case three times. Step 1 involved interpretation of PET images alone, Step 2 involved side-by-side reading of PET and CT images, and Step 3 involved re-evaluation of findings with the results of other screening tests. We assessed inter-observer agreement for each step. Results: Inter-observer agreement for all lesions at each step was moderate, compared to fair agreement for 'Normal' subjects. Inter-observer agreement of 'Cancer' and 'Not malignant' subjects in Step 1 were better than those in Step 2 and 3; however, the differences were not statistically significant. Conclusion: The interpretation of FDG-PET is adequately reproducible, while that of 'Normal' subjects is less reproducible. Improvement of inter-observer variability in assessing physiological FDG uptakes requires universal reporting criteria in FDG-PET. Correlative interpretation of PET, CT and other information may require standardization in subjects with suspected cancer by FDG-PET.

Japanese Journal of Clinical Oncology, 2009

The purpose of this multicenter study was to evaluate the clinical usefulness of positron emissio... more The purpose of this multicenter study was to evaluate the clinical usefulness of positron emission tomography (PET) using 18 F-fluorodeoxyglucose (FDG) for suspected recurrent gastric cancer. Methods: We performed a retrospective review of 92 consecutive patients who underwent PET [either integrated PET/computed tomography (CT) or manual fusion of dedicated PET and CT] scans for post-treatment surveillance of gastric cancer between June 2006 and December 2007. Of these patients, 46 patients were suspected of recurrence by other imaging modalities (Group A), 19 patients were suspected of recurrence by tumor markers without definite findings (Group B) and the remaining 27 patients underwent a PET scan without evidence of recurrence (Group C). The diagnostic performance and prevalence of the clinical impact of FDG-PET were analyzed. Results: Recurrence of gastric cancer was confirmed in 31 patients (67%) in Group A, in 11 patients (58%) in Group B and in 2 patients (7%) in Group C. In addition, colon cancer (n ¼ 3), lung cancer (n ¼ 1) and pulmonary carcinoid (n ¼ 1) were identified in five patients (5%). In patient-basis, the sensitivity, specificity and diagnostic accuracy of PET for recurrence were 81%, 87% and 83%, respectively, in Group A, 73%, 88% and 79%, respectively, in Group B and 50%, 88% and 85%, respectively, in Group C. Therapeutic management was influenced by PET results in 22 patients (48%) in Group A, in 8 patients (42%) in Group B and in 2 patients (7%) in Group C, including cases in which PET was helpful for detecting second primary cancer. Conclusions: PET with FDG yielded useful information in patients with suspected recurrent gastric cancer, especially when recurrence was suspected in the clinical setting.

International Journal of Gynecological Cancer, 2005

Positron emission tomography (PET) using fluorine-18-fluoro-2-deoxy-D-glucose (FDG), which origin... more Positron emission tomography (PET) using fluorine-18-fluoro-2-deoxy-D-glucose (FDG), which originated as a research tool to evaluate glucosemetabolism in cancer tissues, has now become an essential imaging modality for determining the appropriate therapeutic management of various cancer patients. The clinical role of FDG-PET for gynecologic tumors has not been established yet, but FDG-PET has come to be considered one of the important imaging modalities for evaluating patients with gynecological cancers. The objective was to review the literature regarding the utility of FDG-PET in the clinical setting of gynecological malignancies. Many articles reported that FDG-PET could be used for staging and restaging in patients with uterine cervical cancer. Although there is limited data about the feasibility of FDG-PET for endometrial cancer, preliminary results for detecting recurrence were promising. Furthermore, FDG-PET has been reported as a useful imaging modality, especially for restaging, in ovarian cancer, although the prognostic value needs to be fully investigated. Currently, a combined PET/ computed tomography scanner is available, and its clinical application has begun. It is expected that this modality will contribute to the management of gynecological cancers, as has been reported recently for other malignancies.

European Journal of Radiology, 2011

The clinical value of positron emission tomography (PET) using 18 F-fluorodeoxyglucose (FDG) for ... more The clinical value of positron emission tomography (PET) using 18 F-fluorodeoxyglucose (FDG) for follow-up or suspected recurrence of renal cell carcinoma (RCC) has not been fully evaluated. The purpose of this study was to assess the diagnostic performance of FDG-PET for post-operative assessment in patients with RCC. Methods: We reviewed 28 scans in 23 patients who had undergone FDG-PET scans after surgery for RCC. Diagnostic accuracy of visually interpreted PET was evaluated based on final diagnoses obtained histologically or by clinical follow-up at least 6 months. Also, additional information over CT, influence on treatment decisions, and the accuracy of FDG uptake as a predictor of survival were assessed. Results: Recurrence of renal carcinoma was histologically (n = 15) or clinically (n=6) confirmed in 21 of 28 cases. Overall, the sensitivity, specificity, and diagnostic accuracy using FDG-PET were 81%, 71%, and 79%, respectively. In papillary RCC, the sensitivity was 100%; however, that was 75% in clear cell RCC in patient-basis. PET correctly detected local recurrence and metastases in all cases in the peritoneum, bone, muscle and adrenal gland. Additional information was obtained from scans in 6 cases (21%), which influenced 4 therapeutic management in 3 cases (11%). Cumulative survival rates over 5 years in the PET-positive vs. the PET-negative group were 46% vs. 83%, respectively (p = 0.17). Conclusions: FDG-PET would be useful for postoperative surveillance in patients with RCC, although its impact on treatment decisions may be limited. Further investigations are necessary to conclude whether PET has a prognostic value.

Clinical Radiology, 2012

IgG4-related systemic disease (IgG4-RSD) is an emerging clinical entity about which much remains ... more IgG4-related systemic disease (IgG4-RSD) is an emerging clinical entity about which much remains to be elucidated, in terms of its aetiology, pathogenesis, diagnosis, treatment and outcome. Autoimmune pancreatitis (AIP) and Mikulicz Disease (MD) are the two major, well-studied constituents of IgG4-RSD. AIP and MD have common characteristics of forming tumour-mimicking lesions that consist of lymphoplasmacytic infiltrates and fibrosclerosis with numerous Immunoglobulin G4 (IgG4)-positive plasma cells, as well as various multi-organ manifestations of IgG4-RSD. Fluorine-18 fluorodeoxyglucose positron emission tomography / computed tomography (FDG PET/CT) enables acquisition of whole-body images and provides functional information about disease activity, as such it has a valuable role in staging extent of disease, guiding biopsy and monitoring response to treatment. However, FDG PET/CT is likely to be only one component of the management strategy, and clinical, laboratory, imaging and histological findings are crucial in the overall diagnosis of the condition. At present FDG PET/CT does not have a well-established role in the assessment of patients with IgG4-RSD and future prospective studies are required to more accurately define the cost-effectiveness and clinical impact in this patient group.

Clinical Cancer Research, 2012

Purpose: Positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) has been widely use... more Purpose: Positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) has been widely used in the management of colorectal cancer (CRC). However, the relationship between FDG accumulation and KRAS/BRAF mutations has not yet been investigated. The purpose of this study was to investigate whether KRAS/BRAF mutations affect FDG accumulation in CRC. Experimental Design: Retrospective analysis was conducted in 51 patients with CRC who underwent FDG-PET/computed tomographic (CT) scans for staging before primary tumor resection. The maximum standardized uptake value (SUVmax) for the primary tumor and the tumor-to-liver ratio (TLR) were calculated from FDG accumulation and compared between KRAS/BRAF mutated and wild-type groups. Expression levels of glucose transporter-1 (GLUT1) and hexokinase type-II (HXK-II) were assessed by immunohistochemical analysis. Results: Both SUVmax and TLR were significantly higher in the KRAS/BRAF-mutated group compared with the wild-type group (P = 0.0...

Annals of Nuclear Medicine, 2010

Positron emission tomography (PET)/computed tomography (CT) with 18 F-fluorodeoxyglucose (FDG) is... more Positron emission tomography (PET)/computed tomography (CT) with 18 F-fluorodeoxyglucose (FDG) is widely used for post-therapeutic surveillance of malignant lymphoma. Debate still exists as to whether intravenous contrast media during the CT stage of a PET/CT scan should be used. The purpose of this study was to investigate the clinical value of contrast agent in PET/CT in patients with lymphoma following treatment. 122 consecutive patients with malignant lymphoma underwent 146 PET/CT scans to monitor therapeutic response (n = 57) or surveillance during follow-up (n = 89). All patients had a conventional PET/CT scan with low-dose CT without contrast (ldCT), and then a full-dose CT scan with contrast (ceCT). Two datasets were interpreted separately and prevalence of discrepant results between the two methods was evaluated. In addition, differences of diagnostic performance were investigated for restaging. A Self-archived copy in Kyoto University Research Information Repository when monitoring response to therapy. There were no cases in which these techniques demonstrated inconsistent findings. For restaging, the patient-based sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of PET+ldCT were 70%, 91%, 76%, 87%, and 84%, respectively, and those of PET+ceCT were 74%, 92%, 81%, 89%, and 87%, respectively. Discrepant results between the two methods occurred in only 2 of 89 cases (2%). PET/ceCT yielded more accurate findings than PET/ldCT in a limited number of cases. PET/ldCT may, therefore, be sufficient for routine PET/CT scanning for post-therapeutic assessment or restaging of lymphoma patients.

Annals of Nuclear Medicine, 2003

characteristic (ROC) analysis. An average score of the 4 readers for each patient was also define... more characteristic (ROC) analysis. An average score of the 4 readers for each patient was also defined as consensus average index (CAI) and compared between the two images. Results: ROC results indicated no significant differences in detection performance (Averaged areas under ROC curves of 1 h vs. 2 h were 0.92 vs. 0.90 for primary tumor, and 0.81 vs. 0.85 for liver metastases). There were no significant differences in CAIs between 1 h and 2 h PI images in interpreting primary tumor and positive liver metastases, but a significant difference was observed for cases without liver metastases (p < 0.05). Conclusions: The certainty of excluding liver metastases was increased when the 2h image was used, although ROC analysis did not establish a difference between 1 h and 2 h imaging for differentiating malignant and benign lesions in primary pancreatic cancer or its liver metastases.