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.

A Study of CT-derived Radiation Dose Calculation in Lung Q-SPECT/CT Imaging.

Objectives: To investigate the amount of effective dose (ED) due to the computed tomography (CT) component of lung perfusion-single-photon emission computed tomography (Q-SPECT)/CT. Methods: In this single-center retrospective study, imaging data were collected from the clinic database for the period 2016-2022. The 327 patients identified were aged between 20 and 94 years. Tube voltage, tube current, pitch, gantry rotation time, volume CT dose index, and dose-length product (DLP) were recorded. The DLP was then converted to an ED using the conversion factors. The comparison of the ED between two groups was performed using the Mann-Whitney U non-parametric test. Results: ED (mean ± standard deviation, mSv) was 1.20±0.70 for the pulmonary embolism (PE) (-) and 1.54±1.04 for the PE (+) cases (p<0.05). It was observed that there was a 28% increase in the ED for the PE (+) cases. In addition, each of the PE (-) and PE (+) cases was divided into two groups according to the use of the computed tomography dose reduction (CTDR): without CTDR protocol group (non-CTDR) and with CTDR protocol group (CTDR). For those groups, ED were obtained as 0.87±0.72 and 1.55±0.47 for PE (-) cases (p<0.05); 1.56±1.17 and 1.49±0.54 for PE (+) cases (p>0.05) correspondingly. For a deeper understanding, ED was calculated for all three groups formed with different tube voltage values applied for the non-CTDR and CTDR groups.There was a 42% decrease in the ED for group 1 PE (+) compared to group 2 PE (+) (1.21±0.28, 2.07±0.91, p<0.05) and there was a 41% decrease in the ED for group 1 PE (-) compared to group 2 PE (-) cases (1.17±0.32, 1.97±0.65, p<0.05). Conclusion: It could be concluded that the effective DR protocol is the non-CTDR protocol for the PE (-) cases and the application of the tube voltage at the level of 100 kVp for the PE (+) cases.

The Relationship between Planar and SPECT/CT Parameters and Functional Markers in Primary Hyperparathyroidism.

This study aimed to investigate the relationship between quantitative and volumetric parameters of technetium-99-methoxyisobutylisonitrile (99mTc-MIBI) single-photon emission computed tomography/computed tomography (SPECT/CT) imaging and hormonal and biochemical markers in primary hyperparathyroidism (PHPT) patients with single adenoma. In this retrospective study, 70 patients with a single adenoma who underwent 99mTc-MIBI imaging for the diagnosis of PHPT were examined. Early and delayed MIBI lesion/background ratios (eLBR and dLBR), early and delayed lesion/thyroid ratio (eLTR and dLTR), and retention index (RI) were calculated as planar dual-phase scintigraphy parameters. Adenoma volume (Svol) and parathormone (PTH)/Svol ratio were measured as SPECT/CT-derived parameters. Calcium levels exhibited a positive correlation with eLBR (r = 0.33, p < 0.001), dLBR (r = 0.29, p = 0.01), dLTR (r = 0.31, p < 0.001), and PTH/Svol (r = 0.38, p < 0.001). PTH did not correlate with planar parameters and Svol. Among the imaging parameters, only the PTH/Svol ratio showed a negative correlation with phosphorus levels (r = -0.29, p = 0.02). For predicting disease severity, the PTH/Svol ratio exhibited similar diagnostic performance to PTH and phosphorus levels but outperformed the eLBR and dLBR. Both planar and SPECT-derived parameters can provide valuable insights into the functional status of the parathyroid adenoma and the associated disease severity. PTH/Svol ratio, combining imaging and laboratory findings to provide a more comprehensive approach to patient care, could be an exciting new indicator.

Evaluation of diffuse lymphadenopathy via various quantitative PET/CT parameters.

OBJECTIVE: Discovery of diffuse lymphadenopathy (DLAP) in fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) imaging alerts for the existence of many pathologic conditions with severity ranging from benign to malignancy. This study examines the role of various metabolic parameters reflecting 18F-FDG characteristics of organs/tissues to reach an accurate differential diagnosis for further clinical assessment. MATERIALS AND METHODS: Positron emission tomography/CT images of 78 patients with DLAP were reviewed retrospectively. The diameter of the largest lymph node (DLlyn), maximum standardized uptake value (SUVmax) of the liver (L), the largest lymph node (Llyn), spleen (S), and bone marrow (BM) were measured. Ratios to liver SUVmax were calculated for all, resulting LLRmax, SLRmax, and BMLRmax respectively. RESULTS: The diameter of the largest lymph node, Llyn.SUVmax, LLRmax, and SLRmax produced cut-off values as 25.5, 8.86, 2.80, and 0.82 with corresponding sensitivity:specificity values as 65%:83%, 74%:77%, 74%:71%, and 79%:63% respectively for risk stratification of malignant causes. To differentiate lymphoma from sarcoidosis, DLlyn, SLRmax, and BMLRmax were found valuable with cut-off values obtained as 28.5, 0.84, and 1.19 with corresponding sensitivity:specificity values as 79%:91%, 79%:82%, and 54%:91%, respectively.Interdependency between parameters was also evaluated. CONCLUSION: High values of Llyn.Maximum SUV and LLRmax are the main characteristics of lymphoma, metastasis, and sarcoidosis. The diameter of the largest lymph node, SLRmax, and BMLRmax are determined as distinct parameters for distinguishing lymphoma from sarcoidosis. Besides, observed correlation structures amongst some PET/CT parameters were identified as nodal, extranodal, and diffuse patterns for three disease groups except sarcoidosis. These findings extend the knowledge about diagnostic factors based on 18F-FDG PET/CT patterns for DLAP.

Incidental papillary thyroid microcarcinomas in thyroidectomy specimens: A single-center experience from Turkey.

BACKGROUND: Papillary thyroid microcarcinoma (PTM) is a relatively common entity in the general population. PTM is often asymptomatic and is detected incidentally during the histopathological examination of thyroidectomy specimens from operations because of benign thyroid disease. AIMS: The aims of the study are to determine the incidence of incidental papillary thyroid microcarcinomas (IPTMs) in our center, to examine the clinicopathologic characteristics of these tumors, and to present our experiences. MATERIALS AND METHODS: This study includes 827 patients who underwent thyroidectomy operation in our center between January 2013 and June 2017 and were examined histopathologically in the Pathology Clinic. Patients' demographic characteristics, preoperative diagnoses, operative procedure, histopathological findings, and postoperative prognostic indexes are presented. RESULTS AND CONCLUSION: Of the 827 patients, 138 (16.6%) were diagnosed with a malignancy. Of these, 124 were papillary carcinoma, 5 were follicular carcinoma, 4 were lymphoma, 2 were medullary carcinoma, 2 were anaplastic carcinoma, and 1 was poorly differentiated carcinoma. The IPTM incidence rate was 8.01%; the multifocality and bilaterality rates were 23.3% and 13.3%, respectively. In 98.3% of IPTM cases, total thyroidectomies were performed, and in 1.7% of cases, subtotal thyroidectomy was performed followed by complementary thyroidectomy. No relapse or metastasis was detected in any of these cases. A careful histopathological examination of the thyroidectomy specimen is essential because IPTM is frequently skipped in fine needle aspiration cytology. We consider it best to perform total thyroidectomies because bilaterality and multifocality rates are high in IPTM. Long-term life expectancy in these tumors is quite good.

Evaluation of the physical and biological dosimetry methods in iodine-131-treated patients.

The aim of the study was to compare physical and biological dosimetry methods in iodine-131 (I-131)-receiving patients. The present study comprised of 47 patients (mean age: 47.9 ± 15.8 years), treated with I-131. Group I consisted of 17 patients with hyperthyroidism and mean administered activity of this group was 432.9 ± 111 MBq. There were 15 follow-up patients of differentiated thyroid cancer (DTC) in Group II with mean administered activity of 185 ± 22.2 MBq, who were administered scanning dose of I-131. Group III comprised of 15 patients with DTC, ablated with high-dose of I-131, and this group's mean administered activity was 4347.5 ± 695.6 MBq. The whole-body absorbed doses were calculated in all patients both with the Medical Internal Radiation Dosimetry (MIRD) method using MIRDOSE3 software and cytokinesis-block micronucleus (MN) assay-based MN analysis and were compared. The whole-body absorbed dose, calculated by MIRD method, showed very good correlation with the administered I-131 activity (r = 0.89, P < 0.001), but it was moderate in the MN method (r = 0.52, P < 0.01). Absorbed dose estimations with MIRD method were 49.2 ± 20.8 mGy in Group I, 6.5 ± 1.6 mGy in Group II, and 154.3 ± 47.8 mGy in Group III; the differences were statistically significant (P < 0.001), as expected. Pre- and posttreatment MN frequencies differed significantly in all groups (P < 0.05). The whole-body absorbed doses, based on MN method, were 68.2 ± 17.5, 46.0 ± 11.4, and 90.5 ± 26.9 mGy in Groups I-III, respectively. The difference was significant between Group II and Group III (P < 0.01). The mean absorbed dose was 74.6 ± 27.9 mGy with MN versus 68.0 ± 67.1 mGy in MIRD method (P = 0.087) in the entire study population and the correlation was moderate (r = 0.73, P < 0.001). The whole-body absorbed doses, estimated by MN method, showed moderate correlation with administered radioiodine activities in low radioiodine doses and had significantly different and fluctuating values as compared to MIRD method in patients treated with I-131.

Tc-99m MDP Bone SPECT/CT Findings of a Patient Detected with a New Mutation in LEMD3 Gene: A Case of Osteopoikilosis.

Osteopoikilosis is an inherited condition with autosomal dominant trait resulting in sclerotic foci throughout the skeleton. It has been suggested that loss-of-function mutations of LEMD3 gene located on 12q14.3 result in osetopoikilosis. A bp heterozygote deletion was detected in our patient at the cytosine nucleotide at position 1105 with molecular genetic analysis. Although this mutation has not been previously described, it was considered to be the most likely cause of the disease in our patient due to frame shift and premature stop codon formation. As in our case, three phase bone scintigraphy and whole body imaging did not reflect the true extent of lesion sites and lesion activity. SPECT/CT images could reflect lesion location and activity more accurately, and could be a good alternative for differential diagnosis of unexplained bone pain and sclerotic lesions in one examination.

Micronucleus frequencies in groups receiving external or internal radiation.

OBJECTIVE: In the current study, we aimed to explore whether there is alteration between pre- and post-treatment micronucleus (MN) frequencies induced by internal and external ionizing radiation. MATERIALS AND METHODS: The study enrolled a total of 67 patients including patients admitted to our hospital for treatment of hyperthyroidism (n = 17), scanning with low-dose I-131 (n = 15), and ablative therapy with high-dose I-131 (n = 15) at Department of Nuclear Medicine as well as patients with different diagnoses receiving external radiotherapy with various doses and durations at Department of Radiation Oncology (n = 20). Thirty-two patients who received radioactive iodine and returned for a follow-up visit at 1 month. RESULTS: Considering both pre- and post-treatment MN frequencies of each group, lowest MN frequencies were detected for patients undergoing screening with low-dose I-131, and highest MN frequencies were found in radiotherapy patients. Comparison of pre- and post-treatment MN frequencies among hyperthyroidism, when pre- and post-treatment MN frequencies compared among hyperthyroidism, I-131 whole body scanning, ablation, and radiotherapy patient groups differences between MN frequencies were significant for each group (P < 0.05). CONCLUSION: Our study showed that MN analysis might be of value in determining chromosome damage that could potentially occur in patients exposed to internal and external radiation.

Effect of trifluoperazine on Tc-99m sestamibi uptake in patients with advanced nonsmall cell lung cancer.

OBJECTIVE: The aim of this study was to investigate whether there is an effect of trifluoperazine on Tc-99m  methoxyisobutylisonitrile (MIBI) uptake in patients with advanced nonsmall cell lung cancer (NCLC). MATERIALS AND METHODS: A total of 23 patients with biopsy-proven advanced NCLC who had no previous history of chemo-radiotherapy, underwent baseline dual phase planar, single photon emission computed tomography and whole body Tc-99m MIBI scintigraphy performed at 20 and 120 min. After oral administration of trifluoperazine (5 mg, 2 times a day, for 5 days), dual phase Tc-99m MIBI scintigraphy was repeated. For each patient, and for both studies, regions of interest were drawn over the tumor area (T) and over the normal lung area (L) on the contralateral side in transverse slices where tumor was visualized clearly. Then, early and delayed T/L ratios and washout rate (WR) were calculated. RESULTS: Tc-99m MIBI was accumulated in the cancer tissue in all of the patients. Delayed ratio after the oral administration of trifluoperazine (DR2) was significantly higher (P = 0.039) than delayed ratio before trifluoperazine (DR1). We found no significant differences of early ratio before trifluoperazine (ER1) and early ratio after trifluoperazine (ER2), and washout rate before (WR1) and washout rate after trifluoperazine (WR2). CONCLUSION: In patients with advanced NCLC, trifluoperazine treatment in addition to chemotherapy might be useful. However, our results need to be confirmed in larger series of patients.

Bone single-photon emission computed tomography and three-dimensional computed tomography in the diagnosis of low costal variation and pathologies.

In general, there are five lumbar vertebras in normal human subjects. But occasionally there are six. In such a situation, a radiologist need to discern between lumbarization of S1 (S1 vertebra becomes segmented and mimics L5) or due to hypoplastic 12(th) ribs, hence the T12 vertebra is wrongly assumed to be L1. These interesting images serve a multimodality approach to right aplasia/left hypoplasia of 12(th) rib, injury of left 11(th) rib and subluxation of left 11(th) Costovertebral joint in a patient with lumbar back pain.

Radionuclide imaging for breast cancer diagnosis and management: is technetium-99m tetrofosmin uptake related to the grade of malignancy?

There are different scoring systems available for determining the grade of breast cancer malignancy. Breast cancer tumors have been described for grades 1-3 using the modified Nottingham-Bloom-Richardson grading system. Determining the grade is very important for the clinicians to choose the best treatment options. Technetium-99m methoxy isobutyl isonitrile ((99m)Tc-MIBI) and pentavalent (99m)Tc-dimercaptosuccinic acid ((99m)Tc(V)-DMSA) scintigraphy have been used and are under evaluation for being prognostic factors for breast carcinoma. Radionuclide breast imaging not only visualizes the lesion site but also reflects specific biological and functional lesion features, including perfusion, proliferative potential, metabolic activity and receptor status.

Evaluation of interobserver variability of parenchymal phase of Tc-99m mercaptoacetyltriglycine and Tc-99m dimercaptosuccinic acid renal scintigraphy.

OBJECTIVE: The aim of this study was to investigate the variability in the interpretation of parenchymal abnormalities and to assess the differences in interpretation of routine renal scintigraphic findings on posterior view of technetium-99m dimercaptosuccinic acid (pvDMSA) scans and parenchymal phase of technetium-99m mercaptoacetyltriglycine (ppMAG3) scans by using standard criterions to make standardization and semiquantitative evaluation and to have more accurately correlation. MATERIALS AND METHODS: Two experienced nuclear medicine physicians independently interpreted pvDMSA scans of 204 and ppMAG3 scans of 102 pediatric patients, retrospectively. Comparisons were made by visual inspection of pvDMSA scans, and ppMAG3 scans by using a grading system modified from Itoh et al. According to this, anatomical damage of the renal parenchyma was classified into six types: Grade 0-V. In the calculation of the agreement rates, Kendall correlation (tau-b) analysis was used. RESULTS: According to our findings, excellent agreement was found for DMSA grade readings (DMSA-GR) (tau-b = 0.827) and good agreement for MAG3 grade readings (MAG3-GR) (tau-b = 0.790) between two observers. Most of clear parenchymal lesions detected on pvDMSA scans and ppMAG3 scans identified by observers equally. Studies with negative or minimal lesions reduced correlation degrees for both DMSA-GR and MAG3-GR. CONCLUSION: Our grading system can be used for standardization of the reports. We conclude that standardization of criteria and terminology in the interpretations may result in higher interobserver consistency, also improve low interobserver reproducibility and objectivity of renal scintigraphy reports.

99mTcO4 visualization of septic pulmonary emboli during thyroid scintigraphy.

A case of 99mTcO4 accumulation within the thorax is reported, consistent with septic emboli and thyroiditis during routine thyroid scintigraphy for subclinical hyperthyroidism. After antibiotic treatment, repeated 99mTcO4 imaging revealed complete resolution of foci of septic emboli.

The value of Tc-99m tetrofosmin scintimammography in the assessment of P-glycoprotein in patients with breast cancer.

P-glycoprotein (Pgp) overexpression has been shown to be correlated with resistance to chemotherapy in patients with malignant breast tumors. The aim of our study was to investigate the role of technetium-99m-tetrofosmin (99mTc-TF) as a functional imaging agent reflecting Pgp expression in these tumors. We prospectively studied 28 patients (26 females, 2 males; mean age, 53.07±9.88 years; range, 38 to 70 years) with breast cancer to ascertain the relationship between the degree of accumulation (lesion/nonlesion=L/NL) and percentage washout (WO%) rate of 99mTc-TF and expression of Pgp in tumor tissues. All patients received 555-740 MBq of 99mTc-TF intravenously at the arm controlateral to the suffering breast. Planar images were obtained 10 and 120 min post injection from prone lateral and anterior views with an acquisition time of 5 min. Visual and semiquantitative measurements were performed. The L/NL ratios and WO% rates were calculated semiquantitatively. Immunohistochemical studies were performed on paraffin sections using a monoclonal antibody, JSB-1. The L/NL ratios and WO% rates were related with the level of Pgp determined immunohistochemically. Our results showed an inverse correlation between the L/NL ratios of 99mTc-TF and the density of Pgp expression in tumor tissues, whereas there was no appreciable correlation between the tumor WO% rates of 99mTc-TF and the level of Pgp expression (P=0.275). The values for the L/NL ratios were significantly lower for those tumors expressing Pgp at high levels than those with intermediate or no Pgp expression (P<0.002 and P<0.04). In conclusion, although our results warrant further studies, our data strongly suggest that 99mTc-TF imaging is useful to noninvasively determine the presence of multidrug resistance in patients with breast cancer.

Enterogastroesophageal reflux detected on 99m-technetium sestamibi cardiac imaging as a cause of chest pain.

Myocardial perfusion imaging (MPI) with technetium-99m sestamibi (Tc-99m MIBI) is considered a diagnostic technique that is widely used for the investigation of suspected coronary artery disease. Incidental inspection of an extracardiac activity is indirect, but important marker, which can identify a potentially treatable non-coronary cause for chest pain that may mimic cardiac symptoms. Here, we present an illustrative case in which significant enterogastroesophageal reflux of Tc-99m MIBI occurred during the cardiac imaging following prompt hepatobiliary clearance. Because, there was normal myocardial perfusion on MPI, presence of gastroesophageal reflux (GER) on GER scintigraphy and detection of mild inflammation with pathologically confirmed hyperplastic polyp by endoscopy, in view of the above findings we concluded that the probable cause of chest pain was reflux.

The relationship between technetium-99m-methoxyisobutyl isonitrile parathyroid scintigraphy and hormonal and biochemical markers in suspicion of primary hyperparathyroidism.

OBJECTIVE: Technetium-99m-methoxyisobutyl isonitrile (Tc-99m MIBI) has been widely used to evaluate hyperfunctioning autonomous parathyroid glands in patients with elevated intact parathyroid hormone (iPTH) and/or calcium (Ca) level. The aim of this study was to evaluate the relationship between Tc-99m MIBI parathyroid scintigraphy and hormonal and biochemical markers in suspicion of primary hyperparathyroidism (PHPT). MATERIAL AND METHODS: Dual-phase Tc-99m MIBI parathyroid scintigraphy and total serum iPTH, Ca, phosphorus (P) and albumin measurements were performed in 60 patients (52 females, 8 males; mean age, 59.38±12.51 years; range, 34 to 86 years) with suspicion of PHPT. RESULTS: The iPTH median level was 160.3 pg/mL (47.8 to 782.6). Thirty-five of the patients had surgical resection of hyperfunctioning parathyroid glands. Of the 35 patients, parathyroid gland pathology was detected in 30 patients using scintigraphic examination. Tc-99m MIBI parathyroid scintigraphy was negative in 30 patients. The iPTH, Ca and P levels were significantly different between in the Tc-99m MIBI positive group and the negative group, respectively: For iPTH, 202.1 (47.8-782.6) pg/mL versus 111.6 (80.1-373) pg/mL; p<0.001. For Ca, 11.7±1.15 mg/dL versus 10.3±1.05 mg/dL; p<0.001 and for P levels, 2.46±0.62 mg/dL versus 3.40±0.70 mg/dL; p<0.001). There was no significant difference in serum albumin levels between the MIBI positive and MIBI negative groups (4.25±0.27 g/dL versus 4.25±0.41 g/dL; p>0.05). Tc-99m MIBI parathyroid scintigraphy showed good correlation with iPTH level and histopathological diagnosis. Sensitivity and specificity was found 83.3% and 76.7%, respectively at the level of iPTH>147.7pg/mL. CONCLUSION: Tc-99m MIBI parathyroid scintigraphy is most likely to produce identification and localization of a parathyroid adenoma when both iPTH and Ca are elevated as well as decreased P levels. CONFLICT OF INTEREST: None declared.