Pulmonary Artery Diameter Measurement and Semiquantitative Visual Scoring with Q-SPECT-CT in Acute Pulmonary Embolism.

OBJECTIVE: To investigate whether pulmonary artery diameters obtained from lung perfusion single-photon emission computed tomography-computed tomography (SPECT-CT) images and semiquantitative visual scoring (SVS) could serve as predictors of chronic pulmonary thromboembolic disease (CPTED) in acute pulmonary embolism patients (APE). STUDY DESIGN: Observational study. Place and Duration of the Study: Department of Nuclear Medicine, Samsun Provincial Health Directorate, Gazi State Hospital, Samsun, Turkey, from January 2016 to March 2021. METHODOLOGY: A total of 142 patients undergoing lung perfusion SPECT-CT were included in this study. Patients were classified as APE (+) (n=42) and APE (-) (n=100) based on laboratory and radiological findings, clinical diagnosis, and treatment protocol. Non-contrast CT images were used to determine the diameters (mm) of the main (MPA), right (RPA), and left (LPA) pulmonary arteries and the main pulmonary artery/aorta (PA/AO) ratio. All perfusion defects were scored using SVS for the PE (+) group. Seventeen patients with a diagnosis of CPTED were followed up. The scores and arterial diameters of recovered APE and follow-up patients were compared. RESULTS: The mean diameters (mm) of MPA, RPA, and LPA and PA/AO ratio were 29.74±5.51, 21.73±4.11, 22.74±4.16, and 0.83±0.16 in the APE (+) group and 26.18±4.99, 19.35±3.84, 19.49±4.15, and 0.77±0.15 in the APE (-) group, respectively (p<0.001). Mean MPA diameter (mm), total defect (TD), right visual defect (RVD), and PA/AO ratio were 31.67±15.65, 29.88±15.59, 17.65±10.51, and 0.91±0.18 in the CPTED group and 28.06±4.59, 18.92±13.30, 10.4±7.41, and 0.78±0.15 in the recovered APE group, respectively (p<0.05). CONCLUSION: Assessment of pulmonary artery diameter and PA/AO ratio may indicate APE, but TD and RVD scores may be predictive factors for CPTED when included in the assessment along with MPA dilatation and PA/AO ratio. KEY WORDS: Acute pulmonary embolism, Pulmonary artery diameter, Lung SPECT-CT, Chronic pulmonary thromboembolic disease, Semi-quantitative visual scoring.

Guide for Nuclear Medicine Applications During the COVID-19 Outbreak.

A viral pneumonia rapidly spread from Wuhan, China to all countries in late 2019. In February 2020, WHO named as Coronavirus Disease 2019 (COVID-19) and declared the pandemic on March 11, 2020. To prevent the spread of COVID-19, Ministry of Health of Republic of Turkey and international institutions have published documents defining hygiene rules. After the lung computerized tomography (CT) findings which are important in the diagnosis of COVID-19 are described, protection measures against infection were defined in radiology departments. There is no publication involving protection measures for diagnostic and therapeutic procedures in nuclear medicine (NM) (appointment, patient acceptance, imaging and treatment procedures, disinfection etc). There are two reports on CT findings suggesting COVID-19 in 18F-fluorodeoxyglucose positron emission tomography/CT scan. These lung findings detected in hybrid images will be helpful in the early diagnosis of pulmonary involvement. Infected cases may be asymptomatic and can unintentionally disseminate the virus to surrounding people. This advisory guide has been prepared to avoid infection risk in NM clinics. During the COVID-19 outbreak, staff must use proper personal protective equipment and patients should be evaluated as the elective case according to clinical status. A questionnaire should be made for COVID-19. In cancer cases requiring urgent treatment, radionuclide treatment (RNT) should be planned according to the COVID-19 test result. If the result is negative, RNT can be applied; but if not or if the symptoms are present, RNT must be postponed. Following imaging procedures, scanners and room surfaces should be cleaned by personnel with proper disinfection training.

Prognostic risk factors for rare oncocytic variantin 101 cases of papillary thyroid carcinoma.

OBJECTIVE: Oncocytic variant (OV) is an unusual subtype of papillary thyroid cancer whose histopathologic diagnostic criteria, clinicopathologic features and biological behavior are different and have not been comprehensively studied, characterized in literature. Previous studies present conflicting results upon its prognosis. We investigated demographic and clinicopathologic risk factors affecting its prognosis while presenting our clinical experience. SUBJECTS AND METHODS: This is a retrospective cohort study reviewing 101 patients of OV from an archive of 4500 well-differentiated thyroid cancer patients treated with iodine-131 (131I) between 1991 and 2017. Predefined parameters of age, gender, tumor size (TS), total 131I dose, time to recurrent disease, overall survival, extrathyroidal extension, multifocality, vascular invasion, accompanying other variants, capsular status of thyroid gland, initial cervical lymph node (LN) metastases, preablation stimulated thyroglobulin level, background thyroiditis and stage were evaluated by statistical comparison between metastatic and nonmetastatic groups. RESULTS: Seventeen cases (17%) developed metastases/recurrence, 70% of the recurrences occured before 24 months. Four patients (4%) died during the follow-up. Metastatic sites were usually cervical LN, local recurrence in thyroid bed and lungs. Multivariate analysis revealed stage (IV) and TS were the main parameters impacting recurrence/metastases. In the follow-up, isolated cervical LN metastases were found in 41% of metastatic cases, while 12% had sole recurrence in thyroid bed. Eighty eight percent of the metastatic disease included locoregional (cervical) and/or remote LN. The recurrences were associated with initial thyroid masses greater than 3.5cm in diameter. CONCLUSION: We found that the prognosis of OV is not poor in our series. Stage (IV) and tumor size are the main risk factors in metastatic development.

Primary Diffuse Leptomeningeal Melanomatosis of Spine: 18F-FDG PET Findings.

Primary diffuse leptomeningeal melanomatosis is a rare variant of malignant melanoma of the central nervous system, arising from melanocytes of leptomeninges. It may involve leptomeninges and may invade brain superficially. The diagnosis of the disease with conventional imaging techniques is quite difficult. This case demonstrates the F-FDG uptake of primary diffuse leptomeningeal melanomatosis matching with MRI contrast enhancement regions particularly in the lower thoracic and superior lumbar region.

Complementary role of parathormone washout test to 99mTc-MIBI parathyroid scintigraphy and histopathologic analysis of cell types in parathyroid adenomas. / Gammagrafía paratiroidea con 99mTc-MIBI: valor complementario de la paratohormona en el aspirado y análisis histopatológico de los tipos de células en los adenomas paratiroideos.

OBJECTIVE: Parathyroid scintigraphy (PS) can be negative or equivocal (N/E) in a considerable number of cases with highly suspicious clinical findings and biochemical results for parathyroid adenoma (PA). The aims of this study were to investigate the complementary role of parathormone washout test (PWT) to PS in patients with primary hyperparathyroidism (PHPT) and evaluate histopathologic aspects of PAs in comparison with PS results. MATERIAL AND METHODS: Thirty-eight patients with PHPT referred for PS were included in the study. Seventeen patients had both scintigraphic and ultrasonographic findings concordant with PA (Group A). Twenty-one patients having N/E PS, but suspected lesions for PA on ultrasonography (US) formed Group B. PWT was performed for all patients and they underwent the surgical intervention. An adenoma was removed in all patients and the histopathologic cell characteristics were established. RESULTS: The tumor size on US was larger in those patients whose adenomas were seen on the PS (P<.001). The percentages of chief (or principal), oxyphilic and clear cells in PAs were not statistically different between the groups. Serum parathormone level and PWT were not statistically significant between Group A and Group B (P=.095 and P=.04, respectively). CONCLUSION: Although there is not a definitive threshold value, the sensitivity of PS increases with lesion size. While chief cell and oxyphilic cell content of PAs tend to deplete in N/E PS, clear cell rate increases substantially. Combining PS with both US and PWT increases the sensitivity of detection and localization of PAs.

Impact of tall cell variant histology on predicting relapse and changing the management of papillary thyroid carcinoma patients.

OBJECTIVE: There has been much discussion recently about the risk category of tall cell variant (TVC) histology and its effects on the management of papillary thyroid carcinoma (PTC). We, therefore, undertook a retrospective study to compare stage-matched risk factors and recurrence rates between classical PTC (cPTC) patients and patients with TCV histology. SUBJECTS AND METHODS: A total of 3128 well-differentiated thyroid carcinoma patients who were treated and followed-up for more than 5 years in our clinic from 1995 to 2016 were included in this study. There were 2783 PTC (89%) patients, 1113 (40%) of them were cPTC and 56 (2%) of them were TCV patients. RESULTS: In all stages, the stage-matched incidence of extrathyroidal extension (ETE), lymphovascular invasion and initial lymph node metastases were significantly higher in TCV patients than in cPTC patients (P<0.001). Recurrence was in 10 of 27 patients (37%) with TCV and in 91 of 890 (10%) patients with cPTC diagnosed in stage I (odds ratio (OR)=5.16); in 4 of 6 patients with TCV and 18 of 84 (21%) patients with cPTC in stage II (OR=7.33); in 5 of 6 patients with TCV and 11 of 46 (23%) patients with cPTC in stage III (OR=15.90); and in 13 of 17 patients with TCV and 31 of 93 (33%) patients with cPTC in stage IV (OR=6.50). Stage-matched recurrence rates were found significantly higher in all stages of TCV patients than in cPTC patients (OR=8.49, P<0.001). Recurrence with distant metastases was seen more frequently in TCV patients than in cPTC patients (P<0.001) and treatment of metastatic disease was more difficult in TCV patients. CONCLUSION: Tall cell variant was an independent poor prognostic factor in papillary thyroid carcinoma patients even if they were diagnosed at early stages of the disease. Patients with tall cell variant histology required more aggressive therapeutic approach and closer follow-up than classical patients.

Risk factors and stratification for recurrence of patients with differentiated thyroid cancer, elevated thyroglobulin and negative I-131 whole-body scan, by restaging 18F-FDG PET/CT.

OBJECTIVE: In nearly 20%-30% of patients with differentiated thyroid carcinoma (DTC) relapse and 7% of them die during the next 10 years after initial diagnosis. In 10%-30% of patients with DTC after ablation therapy during the follow-up show a negative iodine-131 (131I) whole-body screening test (131I WBS) and increased serum thyroglobulin (Tg) level. Loss of ability of DTC metastatic lesions to trap 131I is associated with pure survival and often aggressive disease. Several studies have shown that in DTC cases non trapping 131I, fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET) can detect recurrence or metastases with high sensitivity (80%-90%). The purpose of this study was to investigate the clinicopathologic features and other related risk factors of patients with DTC having elevated Tg levels and negative 131I WBS in which recurrence was detected by 18F-FDG PET/CT. We tried to study and stratify patients in this grey zone who could benefit from 18F-FDG PET/CT for the detection of metastases/recurrence according to predefined risk factors not investigated by other researchers. SUBJECTS AND METHODS: We studied retrospectively 165 DTC patients with elevated Tg levels and a negative 131I WBS during their follow-up between 2004-2015. Metastases/recurrence was found in 49% of the patients on restaging with 18F-FDG PET/CT and were compared with nonmetastatic group according to predefined risk factors. These factors were also evaluated in true positive and false negative cases. RESULTS: The sensitivity and specificity of 18F-FDG PET/CT for detecting recurrent/metastatic disease were 90% and 98.5%, respectively. No apparent predefined risk factor impacting a false negative 18F-FDG PET/CT was found. Findings in follicular carcinoma, Hürtle cell carcinoma and papillary carcinoma were not different from positive PET findings. The variants of papillary carcinoma also had no statistically difference with regard to 18F-FDG results. CONCLUSION: The most important factors affecting a true positive 18F-FDG PET/CT study were: ETE, high total 131I dose and the SUVmax values over 4.5.

Clinicopathologic features and prognostic factors of tall cell variant of papillary thyroid carcinoma: comparison with classic variant of papillary thyroid carcinoma.

OBJECTIVE: Tall cell variant (TCV), an aggressive form of papillary thyroid carcinoma (PTC), frequently presents with extrathyroidal disease and recurrence. The aim of this study was to evaluate the clinicopathologic features and outcomes of patients with TCV by comparing them with a larger group of patients with classic variant of papillary thyroid carcinoma (cPTC). PATIENTS AND METHODS: A total of 2500 patients with differentiated thyroid carcinoma were treated and monitored during a 23-year period (1992-2015). Of them, 2250 (90%) had PTC and 235 (9.5%) had follicular thyroid carcinoma. Of the 2250 patients, 862 (38.3%) and 70 (3.1%) had cPTC and TCV, respectively. Cases of TCV and cPTC of PTC were compared on the basis of risk factors. RESULTS: Patients with TCV were significantly older compared with cPTC patients (P<0.001). Tumor size was significantly bigger (P=0.01) and preablation thyroglobulin level was significantly higher (P<0.001) in TCV patients than in cPTC patients. The incidence of capsule invasion, extrathyroidal extension, and vascular invasion was significantly higher in TCV (P=0.003, <0.001, and 0.011, respectively). The incidence of initial lymph node metastasis was significantly higher in TCV (P<0.001). Patients with TCV were mostly at an advanced stage compared with patients with cPTC (P<0.001). Development of local or distant metastasis during the follow-up was significantly higher in TCV than in cPTC. Sex and multifocality were not statistically significant. CONCLUSION: TCV has a higher incidence of local or distant metastasis and mortality rate. Thus, it must be treated with the highest possible I ablation doses and followed up carefully.

Evaluation of radiographic and metabolic changes in bone metastases in response to systemic therapy with (18)FDG-PET/CT.

BACKGROUND: The aim of the study was to retrospectively evaluate radiographic and metabolic changes in bone metastases in response to systemic therapy with (18)FDG-PET/CT and determine their roles on the evaluation of therapy response. PATIENTS AND METHODS: We retrospectively evaluated radiographic and metabolic characteristics of bone metastases in 30 patients who were referred for the evaluation of response to systemic therapy with (18)FDG-PET/CT. All patients underwent integrated (18)FDG-PET/CT before and after treatment. RESULTS: The baseline radiographic patterns of the target lesions in responders group were lytic, sclerotic, mixed and CT negative; after treatment the radiographic patterns of all target lesions changed to a sclerotic pattern and attenuation increased (p = 0.012) and metabolic activity decreased (p = 0.012). A correlation was found between decreasing metabolic activity and increasing attenuation of the target lesions (r = -0.55) (p = 0.026). However, in nonresponders group, the baseline radiologic patterns of the target lesions were lytic, blastic, mixed and CT negative; after treatment all lytic target lesions remained the same and one CT negative lesion turned to lytic pattern and the attenuation of the target lesions decreased (p ± 0.12) and metabolic activity increased (p = 0.012). A correlation was found between increasing metabolic activity and decreasing attenuation (r = -0.65) (p = 0.032). An exception of this rule was seen in baseline blastic metastases which progressed with increasing in size, metabolic activity and attenuation. CONCLUSIONS: This study shows that the metabolic activity of lesions is a more reliable parameter than the radiographic patterns for the evaluation of therapy response.

Initial experience of 3 tesla apparent diffusion coefficient values in differentiating benign and malignant thyroid nodules.

PURPOSE: To evaluate the role of diffusion-weighted magnetic resonance imaging (DWMRI) in differentiating benign and malignant thyroid nodules using a 3 Tesla (T) MRI scanner. MATERIALS AND METHODS: Twenty-eight nodules in 25 patients and 14 healthy control cases were included in the study. DWMRI was acquired with 6 b values with a 3T MRI scanner. The apparent diffusion coefficient (ADC) values of the nodules were calculated from reconstructed ADC map images and were compared with the final histopathological diagnoses. RESULTS: The mean ADC value of the benign nodules was 1548 ± 353.4 (×10(-6) mm(2) /s), and the mean ADC of the malignant nodules was 814 ± 177.12 (×10(-6) mm(2) /s). The normal thyroid tissue had a mean ADC value of 1323.43 ± 210.35 × 10(-6) mm(2) /s (958-1689 × 10(-6) mm(2) /s) in the healthy control group. The ADC values were significantly different among the three groups (P = 0.001). An ADC value of 905 × 10(-6) mm(2) /s was determined to be the cutoff value for differentiating benign and malignant nodules, with 90% (55.5-98.3) sensitivity and 100% (81.3-100.0) specificity. CONCLUSION: This study suggests that the ADC values of nodules measured with a 3T MRI scanner could help in differentiating benign thyroid nodules from malignant nodules.

Clinical impact of (18)F-FDG PET/CT on initial staging and therapy planning for breast cancer.

The purpose of this study was to determine the clinical significance of (18)F-FDG PET/CT on initial staging and therapy planning in patients with invasive breast cancer. One hundred and forty-one consecutive, biopsy proven preoperative and 195 postoperative high-risk breast cancer patients who were referred for PET/CT for initial staging were included in this retrospective study. The clinical stage had been determined by conventional imaging modalities prior to the PET/CT scan. Of the 141 examined preoperative patients, 19 had clinical stage I (T1N0), 51 had stage IIA (12 T2N0 and 39 T1N1), 49 had stage IIB (2 T3N0 and 47 T2N1), 12 had stage IIIA (11 T3N1, 1 T2N2), 2 had stage IIIB (2 T4N1) and 8 had stage IV. PET/CT modified the staging for 26% of stage I patients, 29% of stage IIA patients, 46% of stage IIB patients, 58% of stage IIIA patients and 100% of stage IIIB patients. PET/CT scans detected extra-axillary regional lymph nodes in 14 (9.9%) patients and distant metastasis in 41 (29%) patients. PET/CT scans detected multifocal lesions in 30 (21%) patients, multicentric lesions in 21 (14%) patients and malign foci in the contralateral breast (bilateral breast cancer) confirmed by biopsy in 5 (3.5%) patients. Of the examined 195 postoperative patients PET/CT detected axillary lymph nodes in 22 (11%) patients, extra-axillary regional lymph nodes in 21 (10%) patients and distant metastasis in 24 (12%) patients. PET/CT findings altered plans for radiotherapy in 22 (11%) patients and chemotherapy was adapted to the meta-static diseases in 24 (12%) patients. PET/CT was revealed to be superior to conventional imaging modalities for the detection of extra-axillary regional metastatic lymph nodes and distant metastases. These features make PET/CT an essential imaging modality for the primary staging of invasive breast cancer, particularly in patients with clinical stages II and III.

Imaging of extranodal lymphoma with PET/CT.

Hodgkin disease (HD) and non-Hodgkin lymphoma (NHL) represent a spectrum of malignant neoplasms arising from the lymphoid system with an incidence of around 8% of all malignancies. Although they are generally known as tumors of lymph nodes, 25% to 40% of HD/NHL tumors, especially NHL, arise at extranodal sites along the gastrointestinal tract, head and neck, orbit, central and peripheral nervous system, thorax, bone, skin, breast, testis, thyroid, and genitourinary tract. Extranodal involvement is an important pretreatment prognostic factor for patients with lymphoma and its incidence has increased in the past 2 decades. Imaging plays an important role in the noninvasive pretreatment assessment of patients with extranodal lymphoma. This involvement can be subtle and may be overlooked during computed tomography (CT). Positron emission tomography/CT (PET/CT) has evolved into an important imaging tool for evaluation of lymphomas, facilitating the detection of affected extranodal sites even when CT shows subtle or no obvious lesions. Familiarity with extranodal manifestations and suggestive PET/CT features in different sites is important for accurate evaluation of lymphoma. This article reviews the extranodal PET/CT imaging findings regarding HD and NHL.

The effect of about one third craniectomy on the cerebrospinal fluid flow rate as estimated by radionuclide cisternography in normal rabbits.

Since, the effect of a large cranial defect on the cerebrospinal fluid (CSF) flow rate is still not clear, this study was designed to evaluate the effect of craniectomy in rabbits by using a radionuclide technique, under in vivo physiologic conditions. Eleven male New Zealand white rabbits were examined. After the injection of technetium-99m-diethylene-triaminepenta-acetic acid into the fourth ventricle of each rabbit, dynamic acquisition for 60 min (1 min per frame) was performed pre-op followed by about one third craniectomy to each animal. Injection of the radiopharmaceutical and the imaging steps were repeated at 24 h (post-op 24 h) and at 7 days (post-op 7 d) after craniectomy. The region of interest (ROI) was drawn around the injection site and a time activity curve was generated. Slopes of each curve were calculated to detect the flow rate of the radiopharmaceutical from the injection site during 60 min. Besides, the count decreased ratio (ROIcounts of the last frame ROI counts of the first frame X100) was calculated. Our results showed that the pre-op values of the slope of the time-activity curve and the count decreased ratio were decreased 24 h and 7 d post-op but statistically significant was only the difference between the above values pre-op and 7 d post-op (P=0.04, P=0.01 respectively). In conclusion, the data of the present study indicate that the CSF flow rate in rabbits decreased 7 d after one third craniectomy.

Combination of preoperative ultrasonographic mapping and radioguided occult lesion localization in patients with locally recurrent/persistent papillary thyroid carcinoma: a practical method for central compartment reoperations.

PURPOSE: To improve the surgical success and reduce the complication rates, we combine our routine preoperative ultrasound (US) mapping technique with radioguided occult lesion localization (ROLL) in patients with papillary thyroid cancer recurrences in central compartment. MATERIALS AND METHODS: In the morning of surgery, biopsy proven recurrent/persistent tumoral lesions were plotted on a sketch and injected with Tc-99m labeled macroaggregated albumin under US guidance. Thyroid bed exploration was carried out based on the location of biopsy proven lesion with the guidance of intraoperative gamma probe and neck map. The lymphoadipose tissues showing high count rates were resected and labeled separately for histopathologic study. RESULTS: Despite extensive scarring in some patients probe safely guided to lesions. Noninjected tumor foci were searched and successfully resected in the light of neck map that showing topographic relation of injected and noninjected lesions. Among total of 41 excised lesions, 28 metastatic foci ranging from 3 to 38 mm in largest diameter were recognized at final histologic examination. Combination of preoperative mapping with ROLL was found helpful by the operating surgeons in all patients, respectively. Except 2 patients with known distant metastases, undetectable thyroglobulin levels were reached 6 weeks after surgery. CONCLUSIONS: The use of preoperative US-mapping with ROLL in patients with nonpalpable recurrent/persistent papillary thyroid cancer in central compartment is technically safe and effective method. Combination of techniques provides better information about topographical relations of recurrent/persistent lesions during surgery.

FDG PET findings in a case with acute pulmonary silicosis.

A 21-year-old male having a history of 4 years of working at a denim factory as a sandblaster was diagnosed with pulmonary silicosis and he was also an active smoker. Productive cough, dyspnea on effort, night sweats, and weight loss in a short period of time were his complaints. Chronic occupational exposure to tiny particles of silicon dioxide can stimulate parenchymal inflammation, collagen synthesis and, ultimately pulmonary fibrosis called silicosis. A typical history of exposure and chest X-ray is usually enough for diagnosis. No effective treatment exists except supportive care. Although chest X-ray of the patient revealed bilateral disseminated micronodular densities, a peripherally diffuse prominent FDG [(F-18)-2-fluoro-2-deoxy-D-glucose] uptake in both lungs and faint FDG uptake in mediastinal lymph nodes demonstrating active inflammation regions were noted on PET (Positron Emission Tomography) scan. This case was presented to show the active disease discriminated by FDG PET from chronic changes detected by radiological studies. FDG PET can provide additional information to CT regarding the diagnosis of acute silicosis and the rare accelerated silicosis.

Thyroid hemiagenesis and Graves' disease in a child.

Hemiagenesis of the thyroid is a rare malformation and Graves' disease with ophthalmopathy is reported quite rarely in adult patients but is not seen in children. This is a report of an 8-year-old girl with congenital absence of the left thyroid lobe, or hemiagenesis.

Incidental finding of sacral hemiagenesis on the (99m)Tc-MDP bone scan as a casual regression syndrome type II.

A 69 years old woman with chronic low back pain referred to our Department for bone scintigraphy. Patient did not have any other complaint and his physical examination of the patient was normal. Whole-body scan was acquired 3 h after the intravenous injection of 740 MBq of technetium-99m methylene diphosphonate ((99m)Tc-MDP). Distal sacrococcygeal region could not be observed during the visual analysis of the whole-body scan. Pelvic X-rays radiography and pelvic computed tomography of the patient, demonstrated hemiagenesis of the sacrum, which was consistent with type-2 sacral agenesis. Other structural abnormalities were not detected on the pelvic CT scan of the patient. This case is presented to demonstrate the rare congenital anomaly of sacral hemiagenesis causing empty pelvis appearance in the posterior projection of (99m)Tc-MDP whole body bone scan. This congenital anomaly could be associated with extensive abnormalities of the lower vertebrae, pelvis, and spine.