Artificial intelligence technologies in nuclear medicine

The use of artificial intelligence plays a crucial role in developing precision medicine in nuclear medicine. Artificial intelligence refers to a field of computer science aimed at imitating the performance of tasks typically requiring human intelligence. From machine learning to generative adversarial networks, artificial intelligence automized the workflow of medical imaging. In this mini-review, we encapsulate artificial intelligence models and their use in nuclear medicine imaging workflow.

A case of soft tissue hematoma detected incidentally on 99m TC-labelled RBC gastrointestinal bleeding SPECT/CT

We report an incidental finding on 99mTc-labelled RBC gastrointestinal bleeding scintigraphy of a 49-year-old female patient referred to our clinic in order to localize the bleeding site. The patient has also been suffering from chronic renal insufficiency and received several interventions of femoral catheterization. During the follow-up, an intense uptake was observed at the right inguinofemoral area which is evaluated as a large soft tissue hematoma and confirmed by SPECT/CT subsequently. On the 24th h delayed image an activity accumulation along the bowel trace on the right side of the abdomen was seen as evidence of lower gastrointestinal bleeding.

THE COMPARISON OF THE EXTERNAL DOSE RATE MEASUREMENT OF CHILDREN AND ADOLESCENT PATIENTS WITH ADULT PATIENTS TREATED WITH RADIOIODINE THERAPY

The aim of this study is to evaluate the radiation safety of caregiving people contacting the child and adolescent patients with thyroid cancer who received radioactive iodine-131 (RIT) treatment by comparison with external dose rate measurements of adult patients according to their administered activities and days of hospitalization. We retrospectively evaluated external dose rate measurement of 158 children and adolescent patients and 158 adult patients. During the RIT, the hospitalization time were grouped as 2, 3 and 4 d, and the administered activities as <3700, 3700 and >3700 MBq. The values of external dose rate measurements of children and adolescents were statistically significantly higher than the adult group. Different approaches in radiation safety rules are required for children and adolescents. In terms of radiation safety, we suggest that more specific regulations for family members and caregivers should be established and informed.

Prediction of survival and evaluation of diagnostic accuracy whole body 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography in the detection carcinoma of unknown primary origin

PURPOSE

The aim of the current study was to determine the diagnostic accuracy of whole-body 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in detecting carcinoma of unknown primary (CUP).

MATERIALS AND METHODS

A total of 7,636 patients were investigated by FDG-PET/CT examinations at our Institution. We retrospectively evaluated the file records of 432 patients who were referred to FDG PET/CT imaging with a diagnosis of cancer of unknown primary, and included 316 of the patients with histopathologic verification at the final diagnosis. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated. The Kaplan-Meier test was used for survival analysis. Median survival rate was calculated to evaluate the prognostic value of the FDG-PET/ CT findings.

RESULTS

In the search for a primary, FDG-PET/CT findings correctly diagnosed lesions as the site of the primary true positive in 238 cases, 10 findings diagnosed no site of a primary and none was subsequently proven true negative, 12 diagnoses were false positive and 56 were false negative. The sensitivity of FDG-PET/CT is 81% and the specificity 45%. Positive predictive value, negative predictive value and diagnostic accuracy were 95%, 15% and 78%, respectively.

CONCLUSIONS

Whole-body FDG-PET/CT imaging is proven to be useful method in the search for the primary focus and metastases in patients with cancer of unknown primary.

Unilateral ovarian metastasis from gastric mucinous adenocarcinoma visualized on FDG PET/CT

Krukenberg tumor is a metastatic ovarian tumor with primary focus usually seen in the gastrointestinal tract. Metastatic involvement of the ovary is an uncommon manifestation of malignancy. We report a [18F]-fluoro-2-deoxy-D-glucose positron-emission tomography/computed tomography (FDG PET/CT) appearance of solitary unilateral ovarian metastasis in a 44-year-old woman with a history of mucinous adenocarcinoma type of gastric carcinoma. Total hysterectomy with bilateral salpingo-oophorectomy was performed. Histopathological verification determined metastasis of mucinous adenocarcinoma with components of signet-ring cell carcinoma in the right ovary.

Differentiation of incidental intestinal activities at PET/CT examinations with a new sign: peristaltic segment sign

PURPOSE

The aim of this study was to present the effect of the peristaltic segment sign for the differential diagnosis between malignant, physiological and gastrointestinal focal fluorodeoxyglucose (FDG) uptakes as an alternative method to maximum standardized uptake value (SUVmax).

MATERIALS AND METHODS

Gastrointestinal tract (GIT) sections of 823 FDG positron emission tomography/computed tomography (FDG-PET/CT) performed in our center were reviewed retrospectively. Images of these cases that have been reported for positive intestinal focal FDG uptake areas were included. Through the sectional images, any accompanying short segment expanded with air just after or before the uptake area was marked as "positive peristaltism sign". The cases were confirmed with endoscopy plus biopsy (n:42), endoscopy (n:5), laparotomy (n:1), transabdominal biopsy (n:1), enteroclysis (n:1), CT-colonoscopy (n:5), rectal contrast enhanced CT (n:4). Distinguishing features of the sign were analyzed statistically compared to the conventional method for differentiation of malignity.

RESULTS

Localized FDG uptake was reported in 59 of 823 cases. A SUVmax greater than 2.5 with intestinal wall thickening allowed the diagnosis of malignity with sensitivity 33%, specificity 65%, positive predictive value 69% and negative predictive value 46%. The peristaltic segment sign, considered as a benign finding, increased the statistical values to 68%, 80%, 82% and 65%, respectively.

CONCLUSION

In case of gastrointestinal increased focal FDG uptake, the new parameter of peristaltic segment sign may differentiate the physiologic uptakes from the malignant ones more accurately than the conventional SUVmax.

Evaluation of anxiety and depression in patients prior to myocardial perfusion scintigraphy

OBJECTIVE

In myocardial perfusion scintigraphy (MPS) negative results indicate coronary artery diseases which might cause prominent anxiety and other psychological reactions. The aim of this study was to determine anxiety and depression levels of patients prior to MPS procedures.

METHODS

The Hospital Anxiety Depression Scale(HADS) and the State and Trait Anxiety Inventory I and II were used to evaluate the anxiety and depression levels of the patients. Descriptive analyses and independent sample t-test were used for statistical assessment.

RESULTS

The mean score of HADS-anxiety score prior to MPS was 8.1 ± 4.2, whereas the mean HADS depression score was 6.1 ± 3.7. The mean state anxiety score prior to MPS was 39.7 ± 10.6 and the mean trait anxiety score was 45.02 ± 9.1. HAD and state and trait anxiety scores were found to be significantly higher in female patients than male patients and non-smoker patients than smoker patients. Other risk factors such as having bypass operation, myocardial infarction, hypercholesterolemia, diabetes and hypertension were not related to depression and anxiety scores.

CONCLUSION

The results in this study suggest a role for MPS as a risk factor for higher state anxiety. The MPS procedures might lead to an increase in anxiety levels of patients which is possibly associated with anticipation anxiety felt during waiting period and expectation life-threatening.

Intraocular and orbital metastasis as a rare form of clinical presentation of insular thyroid cancer

Insular carcinoma of thyroid is a rare tumor, which accounts for 4 to 6% of thyroid malignancies. Clinically and morphologically it is considered to be in an intermediate position between well-differentiated carcinoma of the thyroid (papillary or follicular) and undifferentiated or anaplastic carcinoma of the thyroid. Capsular and blood vessel invasion is seen frequently, and metastases to regional lymph nodes, lungs and bones are common. The initial presentation of distant metastasis in patients with thyroid cancer is rare. Thus metastatic thyroid carcinoma rarely involves the orbit. We report a rare case of choroidal metastasis from insular thyroid carcinoma.

The evaluation of the external dose measurement of the patients treated with radioiodine therapy

The aim of the study is to compare the results of the external exposure and the range of the dose spread by the patients, hospitalized in two different groups of 3-4 d receiving radioiodine therapy because of having hyperthyroidism (HT) and thyroid cancer (TC). A total of 1989 patients were evaluated retrospectively. Of the total 1517 patients had TC and 472 had HT. External exposure value was taken at hospital discharge and the distance for external measurement was 1 m at the abdominal level. External exposure values of 99.7 % patients were <30 µSv h(-1) and of 0.3 %, >30 µSv h(-1). The results between patient groups with TC and HT at third and fourth days, and the dissimilarity of measurement results within third and fourth days in total patients, without discriminating the day difference, are statistically meaningful. Although 3-d isolation period for 30 µSv h(-1) limit is generally enough, it can be insufficient for some patients. Besides hospitalisation, the radiation safety training must be emphasised by establishing good communication with patients in order to protect their relatives and other people against radiation risk.

Tc-MDP bone scintigraphy in a case with sporodical tumoral calcinosis

Tumoral calcinosis is an uncommon and benign condition characterized by the presence of large calcific soft tissue deposits occurring predominantly in a periarticular location. It generally occurs as a complication of renal dialysis or trauma, and is rarely seen in familial and sporadic cases. Bone scintigraphy is a sensitive method for diagnosing tumoral calcinosis. A 28-year-old female patient with a history of operation due to tumoral calcinosis located bilateral hips, referred to our department. She had a tender palpable mass in the right knee and a fistulized incisional scar overlying the bilateral hip joints. A sporadic case of tumoral calcinosis with relapses was presented.