The relationship between the incision line and position of the latissimus dorsi muscle for subcutaneous implantable cardioverter-defibrillator intermuscular implantations.

INTRODUCTION: Intermuscular implantations of subcutaneous implantable cardioverter-defibrillators (S-ICD) have been recommended, but the position of the anterior border of the latissimus dorsi muscle (LDM) has not previously been evaluated in establishing an incision line to facilitate the intermuscular approach. The objective of this study is to evalua the position and trend of the anterior border of the LDM in patients who are candidates for implantable cardioverter-defibrillators. METHODS: The distance from the back to the anterior border of the LDM (A) and the anterior-posterior width of the chest wall (B) were measured on computed tomography retrospectively, and the ratio (=A/B) was used as the position of the anterior border of the LDM. In addition, the variability and factors affecting the values were evaluated. RESULTS: An analysis was performed on 78 patients, and the position of the anterior border of the LDM (=A/B) exhibited a normal distribution, with a mean value of 0.53 ± 0.062 (0.41-0.69). The position of the anterior border of the LDM tended to be more anterior in younger, taller, male, primary prevention, nonheart failure, low brain natriuretic peptide level, and nondiabetic patients. CONCLUSION: The position of the anterior border of the LDM varied from case to case with variable results. Conventional incisions on the midaxillary line may be inappropriate for intermuscular implantations, and the position of the anterior border of the LDM should be evaluated in each individual case to establish the incision line.

The impact of the procedural parameters on the lesion characteristics associated with AF recurrence: Late-gadolinium enhancement magnetic resonance imaging (LGE-MRI) analysis.

BACKGROUND: Lesion gaps assessed by late-gadolinium enhancement magnetic resonance imaging (LGE-MRI) are associated with the atrial fibrillation (AF) recurrence after pulmonary vein isolation. Animal studies have demonstrated that the catheter-contact force (CF), stability, and orientation are strongly associated with lesion formation. However, the impact of those procedural factors on the lesion characteristics associated with AF recurrence has not been well discussed. METHODS: A total of 30 patients with paroxysmal AF who underwent catheter ablation were retrospectively enrolled. Radiofrequency (RF) applications were performed with 35 W for 30 s in a point-by-point fashion under esophageal temperature monitoring. The inter-lesion distance was 4 mm. The lesions were visualized by LGE-MRI 3 months postprocedure and assessed by the LGE volume (ml), gap number (GN), and average gap length (AGL [mm]). The gaps were defined as nonenhancement sites of >4 mm. The procedural factors including the catheter-CF, stability, and orientation were calculated on the NavX system. RESULTS: Six (20%) of 30 patients had AF recurrences 12 months postablation. A univariate analysis demonstrated that the AGL was associated with AF recurrence (hazard ratio [HR]: 1.20, confidence interval [CI]: 1.03-1.42, p = .02). All AF recurrence were found in patients with an AGL of >7 mm. The catheter-CF and stability were associated with an AGL of >7 mm, but not the orientation (CF-HR: 0.62, CI: 0.39-0.97, p = .038; stability-HR: 0.8, CI: 0.66-0.98, p = .027). CONCLUSIONS: RF ablation with a low CF and poor catheter stability has a potential risk of creating large lesion gaps associated with AF recurrence.

Successful para-aortic lymph node dissection for endometrial cancer with horseshoe kidney: A case report and review of the literature.

Horseshoe kidney (HSK) is considered to impede para-aortic lymph node dissection. We report the case of a 54-year-old female patient with endometrial cancer and HSK, treated successfully with para-aortic lymph node dissection, and present literature review regarding vascular abnormalities associated with HSK affecting para-aortic lymph node dissection. Three-dimensional computed tomography reconstruction revealed the accessory renal artery, supernumerary renal vein and ventral displacement of the renal pelvis and ureter. Abdominal modified radical hysterectomy, bilateral salpingo-oophorec'tomy, pelvic and para-aortic lymph node dissection and omentectomy were then performed. Lymphadenectomy behind the isthmus of the kidney was performed without separation of the isthmus by lifting the kidneys with vessel tape. There were no intraoperative or postoperative complications. Grasping shifted ureter and complicated vascular network of HSK and securing the operative field without division of the isthmus were key to reducing complications and hemorrhage. This case report can serve as a guide for performing para-aortic lymph node dissection safely and effectively in patients with HSK.

Evaluation of 18F-labeled exendin(9-39) derivatives targeting glucagon-like peptide-1 receptor for pancreatic ß-cell imaging.

ß-cell mass (BCM) is known to be decreased in subjects with type-2 diabetes (T2D). Quantitative analysis for BCM would be useful for understanding how T2D progresses and how BCM affects treatment efficacy and for earlier diagnosis of T2D and development of new therapeutic strategies. However, a noninvasive method to measure BCM has not yet been developed. We developed four 18F-labeled exendin(9-39) derivatives for ß-cell imaging by PET: [18F]FB9-Ex(9-39), [18F]FB12-Ex(9-39), [18F]FB27-Ex(9-39), and [18F]FB40-Ex(9-39). Affinity to the glucagon-like peptide-1 receptor (GLP-1R) was evaluated with dispersed islet cells of ddY mice. Uptake of exendin(9-39) derivatives in the pancreas as well as in other organs was evaluated by a biodistribution study. Small-animal PET study was performed after injecting [18F]FB40-Ex(9-39). FB40-Ex(9-39) showed moderate affinity to the GLP-1R. Among all of the derivatives, [18F]FB40-Ex(9-39) resulted in the highest uptake of radioactivity in the pancreas 30 min after injection. Moreover, it showed significantly less radioactivity accumulated in the liver and kidney, resulting in an overall increase in the pancreas-to-organ ratio. In the PET imaging study, pancreas was visualized at 30 min after injection of [18F]FB40-Ex(9-39). [18F]FB40-Ex(9-39) met the basic requirements for an imaging probe for GLP-1R in pancreatic ß-cells. Further enhancement of pancreatic uptake and specific binding to GLP-1R will lead to a clear visualization of pancreatic ß-cells.

Utility of intravoxel incoherent motion magnetic resonance imaging and arterial spin labeling for recurrent glioma after bevacizumab treatment.

Background Detecting recurrence of glioma on magnetic resonance imaging (MRI) is getting more and more important, especially after administration of new anti-tumor agent. However, it is still hard to identify. Purpose To examine the utility of intravoxel incoherent motion (IVIM) MRI and arterial spin labeling-cerebral blood flow (ASL-CBF) for recurrent glioma after initiation of bevacizumab (BEV) treatment. Material and Methods Thirteen patients (7 men, 6 women; age range = 41-82 years) with glioma (high grade, n = 11; low grade, n = 2) were enrolled in the study. IVIM parameters including apparent diffusion coefficient (ADC), true diffusion coefficient (D), and perfusion fraction (f) were obtained with 14 different b-values. We identified tumor progression during BEV therapy by MRI monitoring consisting of diffusion-weighted imaging (DWI), fluid-attenuated inversion recovery (FLAIR) imaging, and contrast-enhanced T1-weighted (CE-T1W) imaging by measuring tumor area. We also measured each parameter of IVIM and ASL-CBF, and calculated relative ADC (rADC), relative D (rD), relative f (rf), and relative CBF (rCBF) by obtaining the ratio between each area and the contralateral cerebral white matter. We calculated the rate of change (Δ) by subtracting values from those from the preceding MRI study, and obtained Spearman's rank correlation coefficient (rs). Results Tumor progression was identified in nine patients (high grade, n = 7; low grade, n = 2). Negative correlations were identified between ΔrD and ΔDWI area (rs = -0.583), and between ΔrD and ΔCE-T1W imaging area (rs = -0.605). Conclusion Tumor progression after BEV treatment can be identified by decreasing rD.

Minimally invasive radical hysterectomy and the importance of avoiding cancer cell spillage for early-stage cervical cancer: a narrative review.

Radical hysterectomy is a standard surgery to treat early-stage uterine cervical cancer. The Laparoscopic Approach to Cervical Cancer (LACC) trial has shown that patients receiving minimally invasive radical hysterectomy have a poorer prognosis than those receiving open radical hysterectomy; however, the reason for this remains unclear. The LACC trial had 2 concerns: the learning curve and the procedural effects. Appropriate management of the learning curve effect, including surgeons' skills, is required to correctly interpret the result of surgical randomized controlled trials. Whether the LACC trial managed the learning curve effect remains controversial, based on the surgeons' inclusion criteria and the distribution of institutions with recurrent cases. An appropriate surgical procedure is also needed, and avoiding intraoperative cancer cell spillage plays an important role during cancer surgery. Cancer cell spillage during minimally invasive surgery to treat cervical cancer is caused by several factors, including 1) exposure of tumor, 2) the use of a uterine manipulator, and 3) direct handling of the uterine cervix. Unfortunately, these issues were not addressed by the LACC trial. We evaluated the results of minimally invasive radical hysterectomy while avoiding cancer cell spillage for early-stage cervical cancer. Our findings show that avoiding cancer cell spillage during minimally invasive radical hysterectomy may ensure an equivalent oncologic outcome, comparable to that of open radical hysterectomy. Therefore, evaluating the importance of avoiding cancer cell spillage during minimally invasive surgery with a better control of the learning curve and procedural effects is needed.

Telehealth Follow-up Using a Real-Time Electrocardiogram Device Improves Electrocardiogram Monitoring Duration and Patient Satisfaction After Catheter Ablation.

Background: There is a strong demand for remote monitoring systems to gather health data. This study investigated the safety, usefulness, and patient satisfaction in outpatient care using telehealth with real-time electrocardiogram (ECG) monitoring after catheter ablation. Methods and Results: In all, 38 patients who underwent catheter ablation were followed up using telehealth. At the 3- and 6-month follow-up, a self-fitted Duranta ECG monitoring device was sent to the patient's home before the online consultation. Patients attached the devices themselves, and the doctors viewed the patients by video chat and performed real-time ECG monitoring. The frequency of hospital visits and the ECG monitoring duration were compared with conventional in-person follow-up data (n=102). The completion rate for telehealth follow-up was 32 of 38 patients (84%). The number of hospital visits during the 6 months was significantly lower with telehealth follow-up than with conventional follow-up (median [interquartile range] 1 [1-1] vs. 5 [3-5]; P<0.0001). However, the ECG monitoring duration was approximately 4-fold longer for the telehealth follow-up (median [interquartile range] 89 [64-117] vs. 24 [0.1-24] h; P<0.0001). No major adverse events were observed during the telehealth follow-up. Patient surveys showed high satisfaction with telehealth follow-up due to reduced hospital visits. Conclusions: A combination of telehealth follow-up with real-time ECG monitoring increased the ECG monitoring duration and patient satisfaction without any adverse events.

Impact of the coverage of risk-reducing salpingo-oophorectomy by the national insurance system for women with BRCA pathogenic variants in Japan.

To determine the impact of the coverage of risk-reducing salpingo-oophorectomy (RRSO) and mastectomy (RRM) as well as genetic testing for BRCA pathogenic variants by the national insurance system in Japan. We compared the clinical background of women who underwent RRSO at our institution before and after its coverage by the national insurance system. Those who underwent RRSO between January 2017 and December 2019 and between April 2020 and March 2022 were classified as Period. A and B, respectively. Overall, 134 women underwent RRSO during the study period. In Period A and B, 45 and 89 women underwent RRSO for the study period was 36 and 24 months, respectively. Compared with Period A, the number of women who underwent RRSO per month increased by threefold in Period B (p < 0.01). In addition, the number of women who underwent surgery for breast cancer along with RRSO increased in Period B (p < 0.01). Although the number of women who underwent concurrent RRM with RRSO in Period B increased, the difference was not statistically significant. Compared with Period A, the number of women diagnosed with BRCA pathogenic variant increased by 3.9-fold, and the proportion of women who underwent concurrent hysterectomy at the time of RRSO decreased from 66 to 7.9% in Period B (p < 0.01). Owing to the introduction of the national insurance system, the number of women who underwent RRSO and concurrent surgery for breast cancer at the time of RRSO increased in Japan.

Middle ear effusion and fungi.

OBJECTIVES: Bacteria and viruses are rarely isolated from the middle ear fluid in cases of otitis media with effusion (OME). However, since endotoxins are often detected in such effusions, it is suspected that patients with OME have a previous history of gram-negative infection. Recently, fungi have drawn attention as microorganisms that cause chronic sinusitis. We investigated the involvement of fungi in the formation of middle ear effusions of patients with OME and eosinophilic otitis media, in which patients have viscous middle ear effusions and a history of adult bronchial asthma indicating definite involvement of eosinophils. METHODS: Middle ear effusions and nasal secretions were collected from patients with eosinophilic otitis media (7 patients) or OME (12 patients), and smears were prepared for methenamine silver staining. The remaining specimens were embedded in Epon and stained with toluidine blue for observation under a light microscope, and ultrathin sections were prepared for examination under an electron microscope. RESULTS: Fungal hyphae were detected in the middle ear fluid in all of the patients with eosinophilic otitis media or OME. Charcot-Leyden crystals (CLCs) were observed in 6 of the 7 patients with eosinophilic otitis media. In regard to the findings in the nasal secretions, fungal hyphae were also detected in the nasal secretions of all patients, whereas CLCs were detected in only 1 patient with eosinophilic otitis media. CONCLUSIONS: It was clarified by use of the methenamine silver staining method that fungi were present in the middle ear fluid in 100% of the studied cases of eosinophilic otitis media or OME. Whether fungi are also present in the middle ear cavity of normal persons is unknown, but the possibility that they may contribute as a cause of both diseases cannot be excluded. Particularly in eosinophilic otitis media, the observation of numerous CLCs in the middle ear fluid suggests that many eosinophils have degenerated. The eosinophil granule proteins released from the degenerated eosinophils can cause epithelial injury of the middle ear. The possibility that fungi induce the eosinophils in the middle ear also cannot be excluded.

Laparoscopic resection surgery for malignant transformation of extragonadal endometriosis by the "pincer" approach.

Up to 1% of women with endometriosis develop endometriosis-associated neoplasms [1]. Most endometriosis-associated malignant tumors develop from the ovarian endometriomas, whereas those developing from extragonadal lesions are extremely rare, estimated at 0.2% [2]. Because they are uncommon, a treatment protocol for the malignant transformation of extragonadal endometriosis lesions has not been clearly defined. When the lesion is confined to the site of origin and R0 resection is achieved, the 5-year survival rate is between 82% and 100%; therefore, complete resection should be performed [3]. The patient in this video had previously undergone hysterectomy, bilateral salpingo-oophorectomy, left nephrectomy, and low-anterior resection of the rectum due to severe endometriosis. Ten years after the surgery, the patient had a 6 cm endometrioid adenocarcinoma developing from the residual endometriosis lesion at the left uterosacral ligament that involved the bladder, left ureter, and rectum. In this case, the tumor was attached to the pelvis due to infiltration of the left sacrospinous ligament. To completely remove the tumor, we used laterally extended endopelvic resection with abdominoperineal resection of the rectum. We used the laparoscopic-perineal-laparoscopic approach (pincer approach) because improved visualization of the left sacrospinous ligament increases the probability of achieving complete resection [4]. Pathological R0 resection was achieved without intraoperative or postoperative complications. Thus, for tumors that are firmly attached to the pelvic floor, the pincer approach can be useful for achieving R0 resection. The informed consent for use of this video was taken from the patient.

Retinol dehydrogenase 10 contributes to cancer stemness and intracellular carbohydrate storage in ovarian clear cell carcinomas.

BACKGROUND: Ovarian clear cell carcinomas (OCCCs) have been recurrent and refractory among the present treatments, so novel therapeutics are urgently needed. OBJECTIVE: The present study accumulates the proof of concept to examine the feasibility of RDH10 as a therapeutic target for treating OCCCs. METHODS: Immunohistochemically, RDH10 expression was evaluated in 111 primary epithelial ovarian cancers, including 55 OCCCs, 31 ovarian endometrioid carcinomas and 25 ovarian serous carcinomas. The spherogenecity provoked by RDH10 was evaluated in OCCC cells. To analyze whether RDH10 promotes carbohydrate storage via the vitamin A-gluconeogenesis pathway, phosphoenolpyruvate carboxykinase 1 (PCK1) protein levels and intracellular carbohydrate content were measured in response to modified RDH10 expression. RESULTS: Abundant RDH10 was expressed specifically in OCCCs. RDH10 promoted spherogenecity and intracellular carbohydrate storage via modulation of PCK1 expression in OCCC cells. CONCLUSIONS: In the present study, abundant RDH10 contributed to cancer cell stemness and intracellular carbohydrate storage in OCCCs. RDH10 is a potentially, new therapeutic candidate for treating OCCC cases.

Clinical Management of Atypical Endometrial Cells of Undetermined Significance Followed by Negative Cytology.

INTRODUCTION: In Japan, endometrial cytology is widely performed to evaluate the status of the endometrium in women with suspected endometrial cancer. A new classification system for endometrial cytology has recently been used: the Yokohama system, based on a descriptive reporting format. This study aimed to clarify the triage for patients with atypical endometrial cells of undetermined significance (ATEC-US) when followed by negative endometrial cytology. METHODS: We enrolled patients diagnosed with ATEC-US at the Cancer Institute Hospital between January 2016 and December 2017, based on the following inclusion criteria: (1) ATEC-US diagnosed by office endometrial cytology, with or without office endometrial biopsy; (2) follow-up endometrial cytology was performed 3-6 months after initial sampling, with a negative result for malignancy; and (3) no prior history of conservative treatment with progestin for endometrial cancer or atypical endometrial hyperplasia (ATEC-A). Among eligible patients, we analyzed those later diagnosed by endometrial biopsy with ATEC-A or carcinoma. RESULTS: Among 187 patients, 65 met the inclusion criteria. Forty-two patients (64.6%) were observed for more than 24 months. Two patients (3.1%) developed ATEC-A during a median observation time of 26.5 months; the times to diagnosis were 32 months and 22 months. DISCUSSION/CONCLUSION: No patient developed ATEC-A or worse within 1 year. For patients with ATEC-US, if negative cytology is obtained at the next examination, a close follow-up is not necessary.

Ventricular arrhythmia events in heart failure patients with cardiac resynchronization therapy with or without a defibrillator for primary prevention.

Background: It is uncertain whether cardiac resynchronization therapy with a defibrillator (CRT-D) provides better survival benefits than a CRT-pacemaker (CRT-P) in heart failure patients with a reduced ejection fraction (≦35%, HFrEF) treated with contemporary HF therapy. Methods: We retrospectively analyzed the ventricular arrhythmia (VAs; sustained ventricular tachycardia/fibrillation) events in HFrEF patients who underwent CRT without a prior history of VAs or aborted sudden cardiac death before the CRT implantation. Between January/2010 and December/2020, a CRT device was implanted in 79 HFrEF patients (mean age: 69 ± 12 years, male: 57, ischemic cardiomyopathy: 16). CRT-D and CRT-P devices were implanted in 50 and 29 patients, respectively, at each physician's discretion. CRT-Ds were indicated in younger patients than were CRT-Ps (66 ± 12 vs. 73 ± 12 years, p = 0.03), but the gender distribution did not differ (female, 24% [12 of 50] vs. 35% [10 of 29], p = 0.44). The VA events during a median follow-up of 3.5-years (interquartile range [IQR]:1.6-5.5) and their predictors were analyzed. Results: VA events occurred in 9 patients with CRT-Ds (18%) and one with a CRT-P (3%, p = 0.08). The VA event rate was significantly lower in patients without a prior non-sustained ventricular tachycardia (NSVT: ≥3 beats; rate, ≥120 bpm; lasting <30 s, HR 0.05; 95% CI 0.01-0.30; p < 0.01) and females (HR 0.11; 95% CI 0.01-0.93; p = 0.04). Of note, no female patients without a prior history of NSVT experienced VA events. Conclusion: HFrEF CRT candidates without a prior history of NSVT and females may obtain less benefit from a primary preventive defibrillator indication.

Antioxidants and Therapeutic Targets in Ovarian Clear Cell Carcinoma.

Ovarian clear cell carcinomas (OCCCs) are resistant to conventional anti-cancer drugs; moreover, the prognoses of advanced or recurrent patients are extremely poor. OCCCs often arise from endometriosis associated with strong oxidative stress. Of note, the stress involved in OCCCs can be divided into the following two categories: (a) carcinogenesis from endometriosis to OCCC and (b) factors related to treatment after carcinogenesis. Antioxidants can reduce the risk of OCCC formation by quenching reactive oxygen species (ROS); however, the oxidant stress-tolerant properties assist in the survival of OCCC cells when the malignant transformation has already occurred. Moreover, the acquisition of oxidative stress resistance is also involved in the cancer stemness of OCCC. This review summarizes the recent advances in the process and prevention of carcinogenesis, the characteristic nature of tumors, and the treatment of post-refractory OCCCs, which are highly linked to oxidative stress. Although therapeutic approaches should still be improved against OCCCs, multi-combinatorial treatments including nucleic acid-based drugs directed to the transcriptional profile of each OCCC are expected to improve the outcomes of patients.

Magnetic resonance imaging findings of endosalpingiosis: a case report.

Endosalpingiosis is characterized by the presence of glands lined by benign tubal-type epithelium outside the fallopian tube. It is usually an incidental finding and rarely occurs as a tumor-like mass lesion. Here, we describe the magnetic resonance imaging findings of endosalpingiosis that presented as a paraovarian multicystic lesion. It exhibited iso to low intensity on T1-weighted images and inhomogeneous high intensity on T2-weighted images. The septa presented relatively iso to slight high intensity on T2-weighted images and strong contrast enhancement on dynamic contrast-enhanced imaging. Endosalpingiosis should be considered as a differential diagnosis in cases of paraovarian multicystic lesions along the uterine serosa.

CT and MR imaging findings of bilateral ovarian metastasis from renal cell carcinoma: a case report.

Secondary ovarian involvement by renal cell carcinoma rarely occurs. Here, we describe the computed tomography and magnetic resonance imaging findings of bilateral ovarian metastases from renal cell carcinoma that demonstrated heterogeneous strong contrast enhancing tumors with flow voids around and within the tumors. In addition, the apparent diffusion coefficients of the malignant tumors were high. These findings were similar to those of renal cell carcinomas at primary and other metastatic sites.

MR imaging findings of unusual leiomyoma and malignant uterine myometrial tumors: what the radiologist should know.

Uterine sarcomas account for less than 1% of gynecological malignancies and 2-5% of all uterine malignancies. Such sarcomas mainly include leiomyosarcoma (LMS) and endometrial stromal sarcoma (ESS). Additionally, inflammatory myofibroblastic tumor (IMT) and endometrial carcinoma arising in adenomyosis can occur as uterine myometrial tumors. Their differentiation from leiomyoma (LM), particularly degenerated LM and the malignant tumors, is challenging, but preoperative diagnosis is very important for the patient's management. We demonstrate the useful and compulsory findings to differentiate between uterine myometrial malignant tumors and degenerated LM with an unusual appearance.

Successful interhospital transfer for extracorporeal cardiopulmonary resuscitation of a patient who had a cardiac arrest after cesarean section.

BACKGROUND: Studies describing the effectiveness of extracorporeal cardiopulmonary resuscitation (ECPR) for peripartum cardiopulmonary arrest are lacking. CASE PRESENTATION: A 39-year-old woman underwent elective cesarean section. Right after surgery, she fell into a cardiac arrest and was promptly transferred to our institute by ambulance. On arrival, we immediately initiated ECPR, within 63 min of the cardiac arrest. Return of spontaneous circulation was achieved 80 min after induction of extracorporeal membrane oxygenation. As the hemodynamics of the patient stabilized, extracorporeal membrane oxygenation was discontinued on day 3 of hospitalization. The patient's cerebral performance category score was 3 at discharge, which improved to 2 after 3 months. CONCLUSION: This case suggests that prompt interhospital transfer and ECPR might be effective for peripartum cardiac arrest due to nonhemorrhagic events.

First-in-Human Evaluation of Positron Emission Tomography/Computed Tomography With [18F]FB(ePEG12)12-Exendin-4: A Phase 1 Clinical Study Targeting GLP-1 Receptor Expression Cells in Pancreas.

Pancreatic ß-cell mass (BCM) has a central importance in the pathophysiology of diabetes mellitus. Recently, pancreatic ß-cell-specific imaging, especially positron emission tomography (PET) with exendin-based probes, has emerged for non-invasive evaluation of BCM. We developed a novel exendin-based probe labeled with fluorine-18, [18F]FB(ePEG12)12-exendin-4 (18F-Ex4) for PET imaging. We subsequently conducted a first-in-human phase 1 study of 18F-Ex4 PET/computed tomography (CT) and investigated the safety and utility for visualizing the pancreas. Six healthy male subjects were enrolled in this study. A low dose (37.0 MBq) of 18F-Ex4 PET/CT was administered (first cohort: n = 2), and subsequently a higher dose (74.0 MBq) was administered (second cohort: n = 4). In the first and second cohorts, 38.6 ± 4.8 and 71.1 ± 4.8 MBq of 18F-Ex4 were administered, respectively. No serious adverse events were observed in both groups. Only one participant in the first cohort showed transient hypoglycemia during the PET scans. 18F-Ex4 PET/CT successfully visualized the pancreas in all participants. The mean standardized uptake value of the pancreas was found to be higher than that in the surrounding organs, except for the bladder and kidney, during the observation. Dosimetry analyses revealed the effective systemic doses of 18F-Ex4 as 0.0164 ± 0.0019 mSv/MBq (first cohort) and 0.0173 ± 0.0020 mSv/MBq (second cohort). 18F-Ex4 PET/CT demonstrated the safety and utility for non-invasive visualization of the pancreas in healthy male subjects. 18F-Ex4 is promising for clinical PET imaging targeting pancreatic ß cells.