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.

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.

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.

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.

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.