Value of artificial intelligence with novel tumor tracking technology in the diagnosis of gastric submucosal tumors by contrast-enhanced harmonic endoscopic ultrasonography.

BACKGROUND AND AIM: Contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS) is useful for the diagnosis of lesions inside and outside the digestive tract. This study evaluated the value of artificial intelligence (AI) in the diagnosis of gastric submucosal tumors by CH-EUS. METHODS: This retrospective study included 53 patients with gastrointestinal stromal tumors (GISTs) and leiomyomas, all of whom underwent CH-EUS between June 2015 and February 2020. A novel technology, SiamMask, was used to track and trim the lesions in CH-EUS videos. CH-EUS was evaluated by AI using deep learning involving a residual neural network and leave-one-out cross-validation. The diagnostic accuracy of AI in discriminating between GISTs and leiomyomas was assessed and compared with that of blind reading by two expert endosonographers. RESULTS: Of the 53 patients, 42 had GISTs and 11 had leiomyomas. Mean tumor size was 26.4 mm. The consistency rate of the segment range of the tumor image extracted by SiamMask and marked by the endosonographer was 96% with a Dice coefficient. The sensitivity, specificity, and accuracy of AI in diagnosing GIST were 90.5%, 90.9%, and 90.6%, respectively, whereas those of blind reading were 90.5%, 81.8%, and 88.7%, respectively (P = 0.683). The κ coefficient between the two reviewers was 0.713. CONCLUSIONS: The diagnostic ability of CH-EUS results evaluated by AI to distinguish between GISTs and leiomyomas was comparable with that of blind reading by expert endosonographers.

Utility of contrast-enhanced harmonic endoscopic ultrasonography for T-staging of patients with extrahepatic bile duct cancer.

BACKGROUND: The value of contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS) for T-staging in patients with extrahepatic bile duct cancer was evaluated. METHODS: This single-center, retrospective study included consecutive patients with extrahepatic bile duct cancer who underwent surgical resection after preoperative EUS, CH-EUS, and contrast-enhanced CT (CE-CT) examinations between June 2014 and August 2017. The capacity of these modalities for T-staging of extrahepatic bile duct cancer was evaluated by assessing invasion beyond the biliary wall into the surrounding tissue, gallbladder, liver, pancreas, duodenum, portal vein system (portal vein and/or superior mesenteric vein), inferior vena cava, and hepatic arteries (proper hepatic artery, right. and/or left. hepatic artery). Blind reading of EUS, CH-EUS, and CE-CT images was performed by two expert reviewers each. RESULTS: 38 patients were eligible for analysis, of which eight had perihilar bile duct cancer and 30 had distal bile duct cancer. Postoperative T-staging was T1 in 6, T2 in 16, and T3 in 16 cases. CH-EUS was superior to CE-CT for diagnosing invasion beyond the biliary wall into surrounding tissue (92.1% vs. 45.9%, P = 0.0002); the ability to detect invasion to other organs did not differ significantly between the two modalities. The accuracy of CH-EUS for T-staging of tumors was better than that of CE-CT (73.7% vs. 39.5%, P = 0.0059). CH-EUS tended to have a better accuracy than EUS for the diagnosis of invasion beyond the biliary wall into the surrounding tissue (92.1% vs. 78.9%, P = 0.074) and T-staging (73.7% vs. 60.5%, P = 0.074). CONCLUSION: CH-EUS is useful for T-staging of extra hepatic bile duct cancer, especially in terms of invasion beyond the biliary wall into the surrounding tissue.

Comparison of radiation exposure between endoscopic ultrasound-guided drainage and transpapillary drainage by endoscopic retrograde cholangiopancreatography for pancreatobiliary diseases.

OBJECTIVES: The transpapillary drainage by endoscopic retrograde cholangiopancreatography (ERCP-D) cannot be performed without fluoroscopy, and there are many situations in which fluoroscopy is required even in endoscopic ultrasound-guided drainage (EUS-D). Previous studies have compared the efficacy, but not the radiation exposure of EUS-D and ERCP-D. While radiation exposure in ERCP-D has been previously evaluated, there is a paucity of information regarding radiation doses in EUS-D. This study aimed to assess radiation exposure in EUS-D compared with that in ERCP-D. METHODS: This retrospective single-center cohort study included consecutive patients who underwent EUS-D and ERCP-D between October 2017 and March 2019. The air kerma (AK, mGy), kerma-area product (KAP, Gycm2 ), fluoroscopy time (FT, min), and procedure time (PT, min) were assessed. The invasive probability weighting method was used to qualify the comparisons. RESULTS: We enrolled 372 and 105 patients who underwent ERCP-D and EUS-D, respectively. The mean AK, KAP, and FT in the EUS-D group were higher by 53%, 28%, and 27%, respectively, than those in the ERCP-D group, whereas PT was shorter by approximately 11% (AK, 135.0 vs. 88.4; KAP, 28.1 vs. 21.9; FT, 20.4 vs. 16.0; PT, 38.7 vs. 43.5). The sub-analysis limited to biliary drainage cases showed the same trend (AK, 128.3 vs. 90.9; KAP, 27.0 vs. 22.2; FT, 16.4 vs. 16.1; PT, 32.5 vs. 44.4). CONCLUSIONS: This is the first study to assess radiation exposure in EUS-D compared with that in ERCP-D. Radiation exposure was significantly higher in EUS-D than in ERCP-D, despite the shorter procedure time.

Utility of contrast-enhanced harmonic endoscopic ultrasonography for predicting the prognosis of pancreatic neuroendocrine neoplasms.

BACKGROUND AND AIMS: Pancreatic neuroendocrine neoplasms (PanNENs), including Grade 1 (G1) or G2 tumors, can have a poor prognosis. This study investigated the value of contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS) for predicting the prognosis of PanNENs. METHODS: This single-center, retrospective study included 47 consecutive patients who underwent CH-EUS and were diagnosed with PanNEN by surgical resection or EUS-guided fine needle aspiration between December 2011 and February 2016. Patients were divided into aggressive and non-aggressive groups according to the degree of clinical malignancy. CH-EUS was assessed regarding its capacity for diagnosing aggressive PanNEN, the correspondence between contrast patterns and pathological features, and its ability to predict the prognosis of PanNEN. RESULTS: There were 19 cases of aggressive PanNEN and 28 cases of non-aggressive PanNEN. The aggressive group included three G1, four G2, three G3 tumors, three mixed neuroendocrine non-neuroendocrine neoplasms, and six neuroendocrine carcinomas. CH-EUS was superior to contrast-enhanced computed tomography for the diagnosis of aggressive PanNEN (P < 0.001): hypo-enhancement on CH-EUS was an indicator of aggressive PanNEN, with sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 94.7%, 100%, 100%, 96.6%, and 97.9%, respectively. Among G1/G2 PanNENs, cases with hypo-enhancement on CH-EUS had a poorer prognosis than those with hyper/iso-enhancement (P = 0.0009). Assessment of 36 resected specimens showed that hypo-enhancement on CH-EUS was associated with smaller and fewer vessels and greater degree of fibrosis. CONCLUSION: Contrast-enhanced harmonic endoscopic ultrasonography may be useful for predicting the prognosis of PanNENs.

Efficacy of a modified double-guidewire technique using an uneven double lumen cannula (uneven method) in patients with surgically altered gastrointestinal anatomy (with video).

BACKGROUND: Balloon enteroscopy-assisted endoscopic retrograde cholangiopancreatography (BE-ERCP) has been reported to be effective for patients with surgically altered gastrointestinal anatomy. However, selective biliary cannulation remains difficult in BE-ERCP. We examined the usefulness of a modified double-guidewire technique using an uneven double lumen cannula (the uneven method) for BE-ERCP in patients with surgically altered gastrointestinal anatomy. METHODS: To clarify the usefulness of the uneven method for selective biliary cannulation in BE-ERCP in comparison to the pancreatic guidewire (PGW) method, 40 patients with surgically altered gastrointestinal anatomy who underwent BE-ERCP with successful placement of a guidewire in the pancreatic duct were evaluated. The uneven method was used in 18 cases (uneven group) and the PGW method was used in the remaining 22 cases (PGW group). RESULTS: The technical success rate of biliary cannulation was higher in the uneven group than in the PGW group (83.3 vs. 59.0%; P = 0.165). In addition, the time to biliary cannulation were significantly shorter in the uneven group than in the PGW group (6 vs. 18 min; P = 0.004; respectively). In the PGW group, post-ERCP pancreatitis (PEP) occurred in 3 of 22 cases (13.6%). No adverse events, including PEP, occurred in the uneven group. CONCLUSIONS: The uneven method may be a useful option of selective biliary cannulation in BE-ERCP for the patients with surgically altered gastrointestinal anatomy.

Wild-Type Anaplastic Lymphoma Kinase Expression in Solitary Pulmonary Nodules: A Potential Marker for Primary Lung Squamous Cell Carcinoma in Patients With Previous Neck Squamous Cell Carcinoma.

In patients with a history of head and neck squamous cell carcinoma (HNSCC), distinguishing between primary lung squamous cell carcinoma (LSCC) and pulmonary metastasis of HNSCC is critical when a solitary pulmonary nodule is observed. However, differentiation in clinical practice remains challenging because no golden-standard immunohistochemical (IHC) marker has been established to identify the primary organ of squamous cell carcinoma (SCC). The anaplastic lymphoma kinase (ALK) gene harbors rearrangements in approximately 4-6% of non-small cell lung cancer (NSCLC) cases. The detection of ALK rearrangements is well-established through anti-ALK IHC. While anti-ALK IHC is primarily positive in adenocarcinoma within NSCLC, wild-type ALK without rearrangements is occasionally detected in other histological types, such as SCC. We report two surgical cases with a history of laryngeal cancer that exhibited solitary pulmonary SCC, in which only the lung lesions demonstrated positivity for wild-type ALK through IHC and fluorescence in-situ hybridization method, allowing for the diagnosis of primary LSCC and following postoperative strategy.

Wernicke encephalopathy with atypical imaging findings in a depressed patient: A case report.

This case report highlights the rare occurrence of Wernicke encephalopathy caused by malnutrition in a depressed patient with atypical imaging findings. A 60-year-old female with depression developed a disturbance of consciousness owing to Wernicke encephalopathy. Magnetic resonance imaging showed abnormal signals in the thalamus and mammillary bodies around the third ventricle, cerebral aqueduct, and fourth ventricle. Abnormal signals were also present in the cerebral cortex around the central sulcus, and an intracranial hemorrhage from the thalamus was observed. Therefore, clinicians should consider Wernicke encephalopathy in the differential diagnosis of altered consciousness in depressed patients. Early assessment of nutritional status and prompt intervention are crucial in cases of prolonged depression-related malnutrition.

The spectrum of TP53 mutations in Rwandan patients with gastric cancer.

BACKGROUND: Gastric cancer is the sixth most frequently diagnosed cancer and third in causing cancer-related death globally. The most frequently mutated gene in human cancers is TP53, which plays a pivotal role in cancer initiation and progression. In Africa, particularly in Rwanda, data on TP53 mutations are lacking. Therefore, this study intended to obtain TP53 mutation status in Rwandan patients with gastric cancer. RESULTS: Formalin-fixed paraffin-embedded tissue blocks of 95 Rwandan patients with histopathologically proven gastric carcinoma were obtained from the University Teaching Hospital of Kigali. After DNA extraction, all coding regions of the TP53 gene and the exon-intron boundary region of TP53 were sequenced using the Sanger sequencing. Mutated TP53 were observed in 24 (25.3%) of the 95 cases, and a total of 29 mutations were identified. These TP53 mutations were distributed between exon 4 and 8 and most of them were missense mutations (19/29; 65.5%). Immunohistochemical analysis for TP53 revealed that most of the TP53 missense mutations were associated with TP53 protein accumulation. Among the 29 mutations, one was novel (c.459_477delCGGCACCCGCGTCCGCGCC). This 19-bp deletion mutation in exon 5 caused the production of truncated TP53 protein (p.G154Wfs*10). Regarding the spectrum of TP53 mutations, G:C > A:T at CpG sites was the most prevalent (10/29; 34.5%) and G:C > T:A was the second most prevalent (7/29; 24.1%). Interestingly, when the mutation spectrum of TP53 was compared to three previous TP53 mutational studies on non-Rwandan patients with gastric cancer, G:C > T:A mutations were significantly more frequent in this study than in our previous study (p = 0.013), the TCGA database (p = 0.017), and a previous study on patients from Hong Kong (p = 0.006). Even after correcting for false discovery, statistical significance was observed. CONCLUSIONS: Our results suggested that TP53 G:C > T:A transversion mutation in Rwandan patients with gastric cancer is more frequent than in non-Rwandan patients with gastric cancer, indicating at an alternative etiological and carcinogenic progression of gastric cancer in Rwanda.

TP53 mutations in Romanian patients with colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) has been ranked as the second most deadly cancer and the third most diagnosed cancer cases for the year 2020. Specifically for Romania, the number of CRC-related deaths in 2019 was estimated at 6307 people, with a standardized mortality rate of 33.8 per 100,000 inhabitants. Although the tumor protein 53 (TP53) gene is intensively studied, there are few data on TP53 mutations in Romanian CRC. Furthermore, since genetic alterations may show geographical differences, our study aimed to analyze the clinical status and TP53 somatic variation in Romanian CRC patients. SUBJECTS AND METHODS: DNA from 40 randomly selected cases of CRC was extracted from formalin-fixed paraffin-embedded tissues and sequenced using direct Sanger sequencing techniques, and variants were annotated according to the recommendations of the Human Genome Variation Society. Novel variants were analyzed using MutationTaster2021 to predict their effects. RESULTS: The mean age was 63.6 years (range 33-85 years) with a male to female ratio of 2.3. More than 45% (18/40) had an advanced cancer stage (≥ stage III). Mutations were found in 21/40 cases (52.5%), with one case having two mutations, giving a total of twenty-two mutations in the TP53 coding DNA. These mutations include 3 (13.6%) insertion-deletion mutations, two of which are novel frameshift mutations: c.165delT (in exon 4) and c.928_935dup (in exon 9), both of which are predicted to lead to nonsense-mediated mRNA decay and are classified as deleterious. The remaining 19 (86.36%) were substitution mutations: 1 nonsense and 18 (81.8%) missense mutations, with G > A (n = 7/19; 36.8%) and C > T (n = 6/19; 31.5%) transitions being the most common. The G > T transversion was found in 21.05% (4/19) of the substitution mutations. CONCLUSION: We have described two novel frameshift mutations in TP53. The discovery of novel mutations following the efforts of The Cancer Genome Atlas and other large-scale cancer genome sequencing projects may be further evidence of the heterogeneous nature of mutations in cancer and may indicate that the identification of carcinogenic mutations is not yet saturated. Further sequencing is therefore needed, especially in less studied populations. Importantly, consideration of their geographical environment will shed light on population-specific carcinogenesis.

Low-dose gemcitabine plus nab-paclitaxel versus standard-dose gemcitabine plus nab-paclitaxel in elderly patients with metastatic pancreatic cancer: A randomized Phase II trial.

Background and Aim: A multicenter, open-label randomized Phase II trial was conducted to determine whether low-dose gemcitabine plus nab-paclitaxel (GnP) could improve tolerability and show equivalent efficacy to the standard-dose GnP for elderly patients with metastatic pancreatic cancer. Methods: Consecutive patients aged ≥65 years with metastatic pancreatic cancer who presented at one of four Japanese referral centers between November 2016 and January 2021 were enrolled. The 60 patients were randomly assigned to low- or standard-dose groups with a 1:1 ratio. Patients in the low-dose GnP group received gemcitabine at a dose of 250 mg/m2 and nab-paclitaxel at 125 mg/m2. Results: Low-dose GnP significantly decreased the rate of cases requiring dose reduction (16.7% vs 63.3%). The response rate (36.7% vs 33.3%) and progression-free survival (7.3 vs 8 months) were comparable between the low- and standard-dose groups as determined by independent review. The difference in the median overall survival between the two groups was not significant (7.9 vs 12 months). The proportion of patients with hematologic and non-hematologic treatment-related adverse events was comparable between the two groups. Conclusion: Low-dose GnP had an equivalent efficacy to conventional therapy; however, it did not reduce adverse events.

Impact of the COVID-19 Pandemic on Glycemic Control and Blood Pressure Control in Patients with Diabetes in Japan.

Objective In this study, we investigated whether and how the COVID-19 pandemic affected glycemic control and blood pressure (BP) control in patients with diabetes mellitus (DM). Methods DM patients whose HbA1c level was measured regularly before and after the declaration of a state of emergency were included in this study. Some patients were given questionnaires about changes in their lifestyle to determine the factors affecting glycemic control and BP control. Results The median HbA1c level of the 804 patients increased significantly from 6.8% before the state of emergency to 7.1% and 7.0% during and after the state of emergency, respectively. This was in contrast to the decrease one year earlier due to seasonal variations. In the 176 patients who responded to the questionnaire, the HbA1c level also increased significantly during and after the state of emergency. The worsening of glycemic control was more pronounced in the group that had achieved HbA1c of <7% before the state of emergency than in those with higher values. Unlike the rise in HbA1c, the BP did not rise during the state of emergency but did rise significantly afterwards. There was no marked decrease in HbA1c or BP after the state of emergency, even in patients who responded that they were much more careful with their diet, ate less, or exercised more. Conclusions The COVID-19 pandemic worsened glycemic control and BP control, even in patients who perceived no marked change in their diet or exercise, suggesting that more active lifestyle guidance is necessary for good treatment of DM patients.

Bispectral index-guided propofol sedation during endoscopic ultrasonography.

BACKGROUND/AIMS: Bispectral index (BIS) monitors process and display electroencephalographic data are used to assess the depth of anesthesia. This study retrospectively evaluated the usefulness of BIS monitoring during endoscopic ultrasonography (EUS). METHODS: This study included 725 consecutive patients who underwent EUS under sedation with propofol. BIS monitoring was used in 364 patients and was not used in 361. The following parameters were evaluated: (1) median dose of propofol; (2) respiratory and circulatory depression; (3) occurrence of body movements; (4) awakening score >8 at the time; and (5) awakening score 2 hours after leaving the endoscopy room. RESULTS: The BIS group received a significantly lower median dose of propofol than the non-BIS group (159.2 mg vs. 167.5 mg; p=0.015) in all age groups. For patients aged ≥75 years, the reduction in heart rate was significantly lower in the BIS group than in the non-BIS group (1.2% vs. 9.1%; p=0.023). Moreover, the occurrence of body movements was markedly lower in the BIS group than in the non-BIS group (8.5% vs. 39.4%; p<0.001). CONCLUSION: During EUS examination, BIS monitoring is useful for maintaining a constant depth of anesthesia, especially in patients 75 years of age or older.

Utility of contrast-enhanced harmonic EUS for diagnosis of portal vein invasion by pancreatic cancer.

Background: The value of contrast-enhanced harmonic EUS (CH-EUS) for diagnosis of portal vein invasion in patients with pancreatic cancer was evaluated. Patients and Methods: This single-center, retrospective study included consecutive patients with pancreatic cancer who underwent both surgical resection after preoperative EUS, CH-EUS, and contrast-enhanced computed tomography (CE-CT) examinations between April 2015 and August 2017. CH-EUS evaluation was performed during the late phase. Portal vein invasion on EUS and CH-EUS was defined as no continuity in the line of the vessel wall. Definition of portal vein invasion on CE-CT was based on the Loyer's criteria. The accuracy of three modalities for diagnosis of invasion into the portal vein was compared using the McNemar's test. Results: Eighty-eight patients (mean age: 71.0 years, ratio of male to female: 48:40) were eligible. Postoperative pathological results were as follows: seven cases of portal vein invasion; 81 cases without. Diagnostic accuracy of EUS, CH-EUS, and CE-CT for diagnosing invasion into the portal vein was 72.7%, 93.2%, and 81.8%, respectively. The differences between CH-EUS and CE-CT (P = 0.0094) and CH-EUS and EUS (P = 0.0022) were significant. EUS and CE-CT were comparable. Conclusion: CH-EUS is useful for diagnosis of portal vein invasion by pancreatic cancer.

Should Contrast-Enhanced Harmonic Endoscopic Ultrasound Be Incorporated into the International Consensus Guidelines to Determine the Appropriate Treatment of Intraductal Papillary Mucinous Neoplasm?

This study aimed to investigate whether the incorporation of contrast-enhanced harmonic endoscopic ultrasound (CH-EUS) into the international consensus guidelines (ICG) for the management of intraductal papillary mucinous neoplasm (IPMN) could improve its malignancy diagnostic value. In this single-center retrospective study, 109 patients diagnosed with IPMN who underwent preoperative CH-EUS between March 2010 and December 2018 were enrolled. We analyzed each malignancy diagnostic value (sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV)) by replacing fundamental B-mode EUS with CH-EUS as the recommended test for patients with worrisome features (WF) (the CH-EUS incorporation ICG) and comparing the results to those obtained using the 2017 ICG. The malignancy diagnostic values as per the 2017 ICG were 78.9%, 42.3%, 60.0%, and 64.7% for Se, Sp, PPV, and NPV, respectively. The CH-EUS incorporation ICG plan improved the malignancy diagnostic values (Se 78.9%/Sp, 53.8%/PPV, 65.2%/NPV 70.0%). CH-EUS may be useful in determining the appropriate treatment strategies for IPMN.

Clinical utility of treatment method conversion during single-session endoscopic ultrasound-guided biliary drainage.

BACKGROUND: Although several techniques for endoscopic ultrasound-guided biliary drainage (EUS-BD) are available at present, an optimal treatment algorithm of EUS-BD has not yet been established. AIM: To evaluate the clinical utility of treatment method conversion during single endoscopic sessions for difficult cases in initially planned EUS-BD. METHODS: This was a single-center retrospective analysis using a prospectively accumulated database. Patients with biliary obstruction undergoing EUS-BD between May 2008 and April 2016 were included. The primary outcome was to evaluate the improvement in EUS-BD success rates by converting the treatment methods during a single endoscopic session. Secondary outcomes were clarification of the factors leading to the conversion from the initial EUS-BD and the assessment of efficacy and safety of the conversion as judged by technical success, clinical success, and adverse events (AEs). RESULTS: A total of 208 patients underwent EUS-BD during the study period. For 18.8% (39/208) of the patients, the treatment methods were converted to another EUS-BD technique from the initial plan. Biliary obstruction was caused by pancreatobiliary malignancies, other malignant lesions, biliary stones, and other benign lesions in 22, 11, 4, and 2 patients, respectively. The reasons for the difficulty with the initial EUS-BD were classified into the following 3 procedures: Target puncture (n = 13), guidewire manipulation (n = 18), and puncture tract dilation (n = 8). Technical success was achieved in 97.4% (38/39) of the cases and clinical success was achieved in 89.5% of patients (34/38). AEs occurred in 10.3% of patients, including bile leakage (n = 2), bleeding (n = 1), and cholecystitis (n = 1). The puncture target and drainage technique were altered in subsequent EUS-BD procedures in 25 and 14 patients, respectively. The final technical success rate with 95%CI for all 208 cases was 97.1% (95%CI: 93.8%-98.9%), while that of the initially planned EUS-BD was 78.8% (95%CI: 72.6%-84.2%). CONCLUSION: Among multi-step procedures in EUS-BD, guidewire manipulation appeared to be the most technically challenging. When initially planned EUS-BD is technically difficult, treatment method conversion in a single endoscopic session may result in successful EUS-BD without leading to severe AEs.

Partial Pancreatic Parenchymal Atrophy Is a New Specific Finding to Diagnose Small Pancreatic Cancer (≤10 mm) Including Carcinoma in Situ: Comparison with Localized Benign Main Pancreatic Duct Stenosis Patients.

BACKGROUND: This study aimed to evaluate and identify the specific CT findings by focusing on abnormalities in the main pancreatic duct (MPD) and pancreatic parenchyma in patients with small pancreatic cancer (PC) including carcinoma in situ (CIS). METHODS: Nine CT findings indicating abnormalities of MPD and pancreatic parenchyma were selected as candidate findings for the presence of small PC ≤ 10 mm. The proportions of patients positive for each finding were compared between small PC and benign MPD stenosis groups. Interobserver agreement between two independent image reviewers was evaluated using kappa statistics. RESULTS: The final analysis included 24 patients with small PC (including 11 CIS patients) and 28 patients with benign MPD stenosis. The proportion of patients exhibiting partial pancreatic parenchymal atrophy (PPA) corresponding to the distribution of MPD stenosis (45.8% vs. 7.1%, p < 0.01), upstream PPA arising from the site of MPD stenosis (33.3% vs. 3.6%, p = 0.01), and MPD abrupt stenosis (45.8% vs. 14.3%, p = 0.03) was significantly higher in the small PC group than in the benign MPD stenosis group. CONCLUSIONS: The presence of partial PPA, upstream PPA, and MPD abrupt stenosis on a CT image was highly suggestive of the presence of small PCs including CIS.