Tumor vascular flow control by MRI after local-regional treatment of small PNATs by AUS-RFA, a case series. The authors and findings. PNATs are rare with indolent behavior. PNATs less than 20 mm have controversial treatment strategies, observation and research, surgery and AUS-RFA. However, a major challenge for these patients is the initial detection of small insulinomas or nonfunctional PNATs. Insulinomas. Case 1. Female, 59 years old. History of hypoglycemia, 10 episodes per week for 10 years. Despite eating constantly. Lab results were normal. Imaging tests were recommended for diagnosis. CT, US, MRI tests were all negative. Therefore, endocytography-guided tissue acquisition was indicated. Here we can see the head and body of the pancreas. Now, the main pancreatic duct. Located in the insulin process, shown in green. Note the hypoechoic and homogeneous nodule. At this time, we observed the wire being inserted into the center of the lesion. Microhistology revealed a well-differentiated neuroendocrine tumor consistent with insulinoma. After a multidisciplinary discussion, UFRFA was indicated. These images show the wire being inserted into the center of the lesion. Accordingly, we performed the ablation. CT, US, and MRI scans after 45 days. In the insulin process, we observed an area of coagulative necrosis in the head, shown in the MRI image. However, a small suspicious hypoechoic area was identified, highlighted in green. At follow-up after five months, the patient reports decreased from 10 to 3 daily episodes of hypoglycemia. Discussed with the multidisciplinary team, a new UFRFA was indicated. A small double negative hypoechoic area, a suspicious area of residual tumor, highlighted in green. A new UFRFA was performed. Case 2, a 70-year-old woman, history of hypoglycemic episodes for four years, weight gain, and a month ago, this patient increased the number of hypoglycemic attacks. All laboratory tests for infection were abnormal, and the MRI identified a nodule in the insulin process. So, UFRFA was indicated. The nodule, insulin process, hypoechoic and homogeneous nodule, acquisition of tissues. Microhistology showed a well-differentiated neuroendocrine neoplasm. UFRFA was indicated. At this time, two ablations were necessary for this session. 30 days later, UFRFA was identified. 30 days later, MRI control showed localized coagulative necrosis in the insulin process without vascular flow. The patient had no symptoms of hypoglycemia, and infection tests were normal. There were no functioning PNEDs. Case 3, a 76-year-old man, asymptomatic. During the check-up, laboratory results showed that chromogen A was increased. Imaging tests were recommended for diagnosis. Only the patient's CT scan was positive. These images show intense hyperuptake, a small hypovascular nodule in the insulin process. Limits of the insulin process. The nodule. USTA was performed. Microhistology showed a well-differentiated PNED without functionality. In the same section, the patient underwent two ablations. The first ablation. The second ablation. Control MRIs show an area of coagulative necrosis near the vascular flow-negative nodule previously identified on the patient's CT. Case 4. A 51-year-old asymptomatic woman. US check-up showed a solid lesion. Imaging tests were recommended. MRI was positive. And they show a solid nodule in the insulin process with 9.8 millimeters. A solid, hapoechoic and homogeneous lesion was identified. And a thymus biopsy was performed. Microhistology showed a well-differentiated, grade 1 neuroendocrine tumor. In the same section, the patient underwent two ablations. First ablation. MRI control shows coagulative area of necrosis near vascular negative node. In this table you will find the main information about patients who survived AUS-RFA. For PNETs smaller than 20 mm, to achieve tumor disappearance on AUS and determine the absence of vascular flow on MRI, more than one ablation in the same session was necessary. In case 1, even though the tumor was smaller than 5 mm, a second session was necessary due to persistent symptoms. Regarding various events, in this series of cases, we observed only one episode of self-limited blood. In conclusion, regarding the diagnosis, AUS tissue procurement should be performed prior to AUS-RFA. AUS-RFA is a safe, well-tolerated, effective, and less invasive method for the treatment of residual tumors. It should be the treatment of choice for patients who do not wish to have surgery or who are medically unable to have surgery. MRI is an excellent method for immediate assessment of vascular flow after AUS-RFA.

MRI-guided

AUS-RFA

pancreatic neuroendocrine tumors

tumor vascular flow

insulinomas