To use MIBI or not to use MIBI? That is the question when assessing tumour cells

Selective venous sampling in primary hyperparathyroidism caused by ectopic parathyroid gland: a case report and literature review

BACKGROUND

As an invasive technique, selective venous sampling (SVS) is considered a useful method to identify a lesion's location to increase the success rate of secondary surgery in patients with primary hyperparathyroidism (pHPT) caused by ectopic parathyroid adenomas.

CASE PRESENTATION

We present a case of post-surgical persistent hypercalcemia and elevated parathyroid hormone (PTH) levels in a 44-year-old woman with previously undetected parathyroid adenoma. An SVS was then performed for further localization of the adenoma, as other non-invasive methods showed negative results. After SVS, an ectopic adenoma was suspected in the sheath of the left carotid artery, previously considered as a schwannoma, and was pathologically confirmed after the second operation. Postoperatively, the patient's symptoms disappeared and serum levels of PTH and calcium normalized.

CONCLUSIONS

SVS can provide precise diagnosis and accurate positioning before re-operation in patients with pHPT.

Pancreatic neuroendocrine tumor detected by technetium-99m methoxy-2-isobutylisonitrile single photon emission computed tomography/computed tomography: A case report

BACKGROUND

Pancreatic neuroendocrine tumors (NETs) account for about 1%–2% of pancreatic tumors and about 8% of all NETs. Computed tomography (CT), magnetic resonance imaging, and endoscopic ultrasound are common imaging modalities for the diagnosis of pancreatic NETs. Furthermore, somatostatin receptor imaging is of great value for diagnosing pancreatic NETs. Herein, we report the efficacy of technetium-99m methoxy-2-isobutylisonitrile (^99mTc-MIBI) single photon emission CT (SPECT)/CT for detecting pancreatic NETs.

CASE SUMMARY

A 57-year-old woman presented to our hospital with a 1-d history of persistent upper abdominal distending pain. The distending pain in the upper abdomen was aggravated after eating, with nausea and retching. Routine blood test results showed a high neutrophil percentage, low leukomonocyte and monocyte percentages, and low leukomonocyte and eosinophil counts. Amylase, liver and kidney function, and tumor markers alpha-fetoprotein, carcinoembryonic antigen, and cancer antigen (CA) 125, CA72-4, CA19-9, and CA153 were normal. Abdominal CT showed a mass, with multiple calcifications between the pancreas and the spleen. The boundary between the mass and the pancreas and spleen was poorly defined. Contrast-enhanced CT revealed that the upper abdominal mass was unevenly and gradually enhanced. ^99mTc-MIBI SPECT/CT revealed that a focal radioactive concentration, with mild radioactive concentration extending into the upper abdominal mass, was present at the pancreatic body and tail. The ^99mTc-MIBI SPECT/CT manifestations were consistent with the final pathological diagnosis of pancreatic NET.

CONCLUSION

^99mTc-MIBI SPECT/CT appears to be a valuable tool for detecting pancreatic NETs.

Single-cell multi-modal GAN reveals spatial patterns in single-cell data from triple-negative breast cancer

Exciting advances in technologies to measure biological systems are currently at the forefront of research. The ability to gather data along an increasing number of omic dimensions has created a need for tools to analyze all of this information together, rather than siloing each technology into separate analysis pipelines. To advance this goal, we introduce a framework called the single-cell multi-modal generative adversarial network (scMMGAN) that integrates data from multiple modalities into a unified representation in the ambient data space for downstream analysis using a combination of adversarial learning and data geometry techniques. The framework’s key improvement is an additional diffusion geometry loss with a new kernel that constrains the otherwise over-parameterized GAN. We demonstrate scMMGAN’s ability to produce more meaningful alignments than alternative methods on a wide variety of data modalities and that its output can be used to draw conclusions from real-world biological experimental data.

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Integrating data from multiple modalities into one analysis

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Using data geometry to regularize cycle-consistent GANs

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Quantifying uncertainty through noise augmentation

Biological experimental data are increasingly being generated along multiple different axes, with new and more complex technologies specializing in particular measurements being developed every year. Measuring a single subject or system with multiple specialized data-collecting tools creates a natural interest in integrating the results of these individual instruments to form a single unified view. The model introduced here presents a computational technique designed for this purpose. With the single-cell multi-modal GAN (scMMGAN), there is an opportunity to measure along many different omic directions and synthesize the information from each into one larger understanding of the system under study.

Benign Parathyroid Hyperplasia With Incidental Pulmonary Seeding on 99mTc-MIBI Scintigraphy and FDG PET/CT

ABSTRACT

A 50-year-old woman with end-stage renal disease presented with recurrent hyperparathyroidism after parathyroidectomy. 99mTc-MIBI scintigraphy did not show MIBI-avid lesion in the neck or mediastinum but in bilateral lung fields instead. On suspicion of malignancy, 18F-FDG PET/CT was performed and depicted no significant FDG uptake throughout the whole body. After resection of the pulmonary nodules, the final histopathology revealed benign parathyroid hyperplasia with pulmonary seeding, which is exceptionally a rare entity.

Updates in Molecular Breast Imaging

Molecular breast imaging (MBI) is a nuclear medicine study performed with dedicated gamma camera systems optimized to image the uptake of Tc-99m sestamibi in the breast. MBI provides a relatively low-cost and simple functional breast imaging method that can identify breast cancers obscured by dense fibroglandular tissue on mammography. Recent studies have also found that background levels of uptake in benign dense tissue may provide breast cancer risk information. This article discusses the latest updates in MBI technology, recent evidence supporting its clinical use, and work in progress that may aid in wider adoption of MBI.

Molecular Imaging with 18F-FDG PET/CT and 99mTc-MIBI SPECT/CT in Osteitis Fibrosa Cystica Generalisata

Benign so-called “brown tumors” secondary to hyperparathyroidism are a rare diagnostic pitfall due to their impressively malignant-like character in various imaging modalities. We present the case of a 65-year-old male patient with multiple unclear osteolytic lesions on prior imaging suspicious for metastatic malignant disease. Eventually, findings of ¹⁸F-FDG PET/CT staging and ^99mTc-MIBI scintigraphy resulted in revision of the initially suspected malignant diagnosis. This case illustrates how molecular imaging findings non-invasively corroborate the correct diagnosis of osteitis fibrosa cystica generalisata with the formation of multiple benign brown tumors.

Role of post-therapy 99mTc-MIBI single-photon emission computed tomography/computed tomography scan in predicting survival in patients with high-grade glioma

OBJECTIVE

High-grade gliomas (HGGs) carry dismal prognosis with survival typically reported as less than a year. We explored the predictive value of qualitative and quantitative evaluations of post-treatment 99m-technetium-labelled methoxyisobutylisonitrile (99mmTc-MIBI) brain single-photon emission computed tomography-computed tomography (SPECT/CT) tumor uptake in relation to overall survival (OS) in patients with HGG.

METHODS

Thirty patients with pathologically or radiologically documented high-grade glioma (HGG) were prospectively recruited for this study (24 male, 6 female; mean age 43 ± 14 years). All patients had a clinical or radiological suspicion of residual/recurrent tumor after initial therapy. 99mTc-MIBI brain SPECT/CT scanning was performed, and the scans were evaluated qualitatively on a five-point probability score (1-5, scores ≥3 considered positive for residual/recurrent tumor); and quantitively via drawing volumes of interest (VOI) on the suspected lesions and normal contralateral brain tissue. All patients were followed up for 1 year or till death.

RESULTS

Positive visual MIBI results were associated with poor survival. Among 10 patients with negative MIBI scores, only two patients died (OS = 75%), while 11/20 patients reported positive on MIBI died, with a median survival of 9 months (OS = 14.5%; P = 0.03). All patients with active isocontour volume ≤1.96 cm3 were alive at the end of the study, compared to a median survival of 9 months and OS of 12% for patients with an isocontour volume of >1.97% (P = 0.003).

CONCLUSION

In patients with HGG, post-therapy brain SPECT/CT with 99mTc-MIBI can provide useful prognostic information.

Quantitative dual isotope 123iodine/99mTc-MIBI scintigraphy: A new approach to rule out malignancy in thyroid nodules

BACKGROUND

The aim of this study was to evaluate the role of dual isotope ¹²³Iodine/^99mTc-MIBI thyroid scintigraphy (IMS) in discriminating between malignant and benign lesions in indeterminate nodules using quantitative analysis methods.

METHODS

Thirty-five consecutive patients with thyroid nodules of indeterminate or non-diagnostic cytology and cold on ¹²³Iodine scintigraphy (10 Bethesda I, 24 Bethesda III-IV, 1 in which cytology was impossible) underwent IMS between 2017 and 2019 with uptake quantification at two time points ahead of thyroidectomy: early and late. Images were analyzed by two blinded physicians.

RESULTS

Twelve nodules were malignant and 23 benign on histopathology. Mean uptake values were lower in benign than in malignant nodules at both time points: early, 8.7±4.1 versus 12.9±3.5 (P=0.005); and late, 5.3±2.7 versus 7.7±1.1 (P=0.008). Interobserver reproducibility was excellent. The intraclass correlation coefficient was 0.86 in benign and 0.92 in malignant lesions for early uptake result (ER) and 0.94 and 0.85 respectively for late uptake result (LR). The optimal LR cut-off  to exclude a diagnosis of malignancy was set at 5.9 . The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of this cut-off were, respectively, 100%, 65.2%, 60%, 100% and 77.1%.

CONCLUSION

Despite some study limitations, quantitative analysis of ^99mTc-MIBI thyroid scintigraphy had a good reproducibility, which could help to rule out malignancy in non-diagnostic or indeterminate thyroid nodules and thereby reducing the number of patients undergoing unnecessary surgery when LR is below 5.9.

THE ROLE OF TUMOR-SEEKING RADIOPHARMACEUTICALS IN THE DIAGNOSIS AND MANAGEMENT OF ADRENAL TUMORS

Context

The variety of tumor-seeking radiopharmaceuticals, which are currently in clinical use, may have a potential role as imaging agents for adrenal gland tumors, due to physiological characteristics of this organ.

Objective

The purpose of this study was to evaluate the diagnostic potential of ^99mTc-HYNIC-TOC, ^99mTc(V)-DMSA, and ^99mTc-MIBI in the assessment of adrenal tumors, by correlating with imaging findings and histopathologic results.

Design

The research is designed as a cross-sectional prospective study.

Patients and method

The study included 50 patients with adrenal tumors (19 hormone-secreting and 31 nonfunctioning) and 23 controls without adrenal involvement. In all patients, single-photon emission computed tomography (SPECT) was performed, using qualitative and semiquantitative analysis. The tumor to non-tumor tracer uptake was conducted by using a region-of-interest technique. Adrenal to background (A/B) ratio was calculated in all cases.

Results

^99mTc-HYNIC-TOC scintigraphy showed a high statistical significance between A/B ratios, while other two tracers resulted in a lower sensitivity, specificity and accuracy. Futhermore, ^99mTc-HYNIC-TOC could have a high diagnostic yield to detect adrenal tumors (the receiver-operating-characteristic curve analysis, A/B ratio cut-off value of 8.40).

Conclusion

A semiquantitative SPECT analysis showed that ^99mTc-HYNIC-TOC is a highly sensitive tumor-seeking agent for the accurate localization of adrenal tumors.

Background Parenchymal Uptake on Molecular Breast Imaging and Breast Cancer Risk: A Cohort Study

BACKGROUND. Background parenchymal uptake (BPU) on molecular breast imaging (MBI) was identified in a case-control study as a breast cancer risk factor beyond mammographic density. To our knowledge, this finding has not yet been confirmed in a cohort study. OBJECTIVE. The objectives of this study were to examine the association of BPU with breast cancer and to estimate the absolute risk and discriminatory accuracy of BPU in a cohort study. METHODS. A retrospective cohort was established that included women without a history of breast cancer who underwent MBI from 2004 to 2015. Radiologists who were blinded to future breast cancer diagnoses assessed BPU on baseline MBI examinations as low (photopenic or minimal) or elevated (mild, moderate, or marked). Associations of BPU with breast cancer were estimated using multivariable Cox proportional hazards models of the time to diagnosis. The 5-year absolute risk was calculated for study subgroups. The discriminatory accuracy of BPU was also assessed. RESULTS. Among 2992 women (mean age, 56.3 years; SD, 10.6 years) who underwent MBI, breast cancer events occurred in 144 women (median follow-up, 7.3 years). Median time to diagnosis after MBI was 4.2 years (range, 0.5-11.6 years). Elevated BPU was associated with a greater breast cancer risk (hazard ratio [HR], 2.39; 95% CI, 1.68-3.41; p ≤ .001). This association remained in postmenopausal women (HR, 3.50; 95% CI, 2.31-5.31; p < .001) but was not significant in premenopausal women (HR, 1.29; 95% CI, 0.72-2.32; p = .39). The 5-year absolute risk of breast cancer was 4.3% (95% CI, 2.9-5.7%) for women with elevated BPU versus 2.5% (95% CI, 1.8-3.1%) for those with low BPU. Postmenopausal women with dense breasts and elevated BPU had a 5-year absolute risk of 8.1% (95% CI, 4.3-11.8%) versus 2.8% (1.8-3.8%) for those with low BPU. Among postmenopausal women, discriminatory accuracy for invasive cancer was improved with the addition of BPU versus use of the Gail risk score alone (C statistic, 65.1 vs 59.1; p = .04) or use of the Breast Cancer Surveillance Consortium risk score alone (C statistic, 66.4 vs 60.4; p = .04). CONCLUSION. BPU on MBI is an independent risk factor for breast cancer, with the strongest association observed among postmenopausal women with dense breasts. In postmenopausal women, BPU provides incremental discrimination in predicting breast cancer when combined with either the Gail model or the Breast Cancer Surveillance Consortium model. CLINICAL IMPACT. Observation of elevated BPU on MBI may identify a subset of women with dense breasts who would benefit most from supplemental screening or preventive options.

99mTC-sestamibi breast imaging: Current status, new ideas and future perspectives

Here we proposed the most recent innovations in the use of Breast Specific Gamma Imaging with ⁹⁹mTc-sestamibi for the management of breast cancer patients. To this end, we reported the recent discoveries concerning: a) the implementation of both instrumental devices and software, b) the biological mechanisms involved in the ⁹⁹mTc-sestamibi uptake in breast cancer cells, c) the evaluation of Breast Specific Gamma Imaging with ⁹⁹mTc-sestamibi as predictive markers of metastatic diseases. In this last case, we also reported preliminary data about the capability of Breast Specific Gamma Imaging with ⁹⁹mTc-sestamibi to identify breast cancer lesions with high propensity to form bone metastatic lesions due to the presence of Breast Osteoblast-Like Cells.

[Investigation of the metabolic features of primary glioblastomas by Tc-MIBI SPECT/CT and evaluation of their effect on disease prognosis]

OBJECTIVE

To study the effect of metabolic characteristics of the tumor determined by 99mTc-MIBI single-photon emission computed tomography (SPECT) and various molecular genetic features on the outcomes of combination treatment of hemispheric glioblastomas.

MATERIAL AND METHODS

This single-center prospective cohort study involved 68 patients aged 25-78 years (38 males and 30 females) with primary glioblastomas. Hypermetylation of the promotor region of the MGMT gene was observed in 24 (42%) out of 57 patients. The IDH1 mutation was revealed in two (3.5%) patients. The catamnestic data were available for 66 out of 68 patients. The first SPECT/CT study was carried out before chemoradiation therapy; the second SPECT/CT study was performed after the chemoradiation therapy. In each study, quantitative measures were calculated for the early (15-30 min after the patient had received a radiopharmaceutical) and late (after 45-60 min) phases.

RESULTS

The actuarial survival rates after 12 and 24 months were 69.6 and 29.1%, respectively. The median overall survival rate was 17.5 months (95% CI 12.9-20.3). Favorable prognostic factors for overall survival included the higher uptake index (UI) in the late phase compared to UI in the early phase of the first SPECT/CT study (p=0.0444), dynamics of changes in UI during the second SPECT/CT compared to baseline over 10% (p=0.0436), MGMT hypermethylation (p=0.0003), and duration of the period between surgery and initiation of chemoradiotherapy being <1 month (p=0.0008). No statistically significant correlations were revealed between the absolute UI values in the tumor and its molecular genetic features.

CONCLUSION

The ^99mTc-MIBI SPECT/CT can be used to predict overall survival and to plan radiation therapy of glioblastoma as it is more readily available at primary healthcare facilities than amino acid PET.

Clinical usefulness of 99mTc-HYNIC-TOC, 99mTc(V)-DMSA, and 99mTc-MIBI SPECT in the evaluation of pituitary adenomas

Background

The aim of this study was to evaluate the behavioral uptake and ability to diagnose pituitary adenoma (PA) using tumor-seeking radiopharmaceuticals, and to provide a semiquantitative analysis of tracer uptake in the pituitary region.

Patients and methods

The study included 33 (13 hormonally active and 20 nonfunctioning) patients with PA and 45 control participants without pituitary involvement. All patients (n=78) underwent single photon emission computed tomography (SPECT) imaging with technetium-99m-labeled hydrazinonicotinyl-tyr³-octreotide (^99mTc-HYNIC-TOC), dimercaptosuccinic acid (^99mTc(V)-DMSA) and hexakis-2-methoxyisobutylisonitrile (^99mTc-MIBI). A semiquantitative analysis of abnormal uptake was carried out by drawing identical regions of interest over the pituitary area and the normal brain on one transverse section that shows the lesion most clearly. The pituitary uptake to normal brain uptake (P/B) ratio was calculated in all cases.

Results

The result of this study confirms that the SPECT semiquantitative method, with all three tracers, showed statistically significant differences between the PA group and the controls. However, ^99mTc-HYNIC-TOC scintigraphy could have the highest diagnostic yield because of the smallest overlap between the P/B ratios between adenoma versus nonadenoma participants (the receiver operating characteristic curve P/B ratio cut-off value was 13.08). In addition, only ^99mTc-MIBI SPECT have the diagnostic potential to detect secreting PAs, with statistically significant differences between groups (P<0.001), with an receiver operating characteristic curve P/B ratio cut-off value of 16.72.

Conclusion

A semiquantitative analysis of increased focal tracer uptake in the sellar area showed that ^99mTc-HYNIC-TOC is a highly sensitive and reliable tumor-seeking agent for detecting PA, whereas ^99mTc-MIBI SPECT is a highly sensitive and specific method in differentiating hormone-secreting pituitary tumor.

Clinical Significance of Incidental Pituitary TC-99m MIBI Uptake on Parathyroid Spect and Factors Affecting Uptake Intensity

OBJECTIVE

(1)To define a quantitative cutoff value for incidental pituitary Technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) uptake above which is of clinical importance and (2) to investigate possible factors affecting the intensity of uptake in pituitary adenoma.

MATERIALS AND METHODS

A retrospective analysis of 55 patients with a simultaneous parathyroid single-photon emission computed tomography and pituitary magnetic resonance imaging were included. Twenty-four patients with pituitary adenoma were chosen as the study group and 31/55 patients who had no signs of a pituitary adenoma were included in the control group. Mean count values (count/pixel) for pituitary region of interest (ROI)/mean value for normal cortical region ROI (P/C) were calculated in both groups. Median P/C values were compared. A cutoff value for P/C was calculated as a quantitative parameter to indicate pituitary tumors. Possible contributing factors in intensity of pituitary Tc-99m MIBI uptake were investigated.

RESULTS

Median P/C ratios were significantly higher in the study group (p < 0.001). A cutoff value of 7.675 was found for P/C to have a sensitivity, spesificity, positive predictive value, and negative predictive value 100%, 96.8%, 96%, and 100%, respectively. There was no correlation between investigated factors and degree of pituitary Tc-99m MIBI uptake.

CONCLUSIONS

Incidental pituitary Tc-99m MIBI uptake values above 7.675 for P/C are suspicious for pituitary adenoma and can be further investigated clinically and radiologically. Tc-99m MIBI uptake is not affected from the biochemical nature of the adenoma, the therapies received, size, local invasion, or cystic necrotic component of the tumor.

(99m)Tc-Methoxy-Isobutyl-Isonitrile Scintigraphy Is a Useful Tool for Assessing the Risk of Malignancy in Thyroid Nodules with Indeterminate Fine-Needle Cytology

BACKGROUND

Thyroid nodular disease is a very common clinical problem. The diagnostic algorithm includes laboratory tests, thyroid ultrasound (US), thyroid scintigraphy, and, if necessary, US-guided fine-needle aspiration cytology. However, cytology results are reported as indeterminate in a not negligible number of patients. This is a central problem in the workup of patients, since about 55-85% of those undergoing surgery do not have thyroid cancer at final histology diagnosis. The aim of this study was to evaluate prospectively the role of (99m)Tc-methoxy-isobutyl-isonitrile ((99m)Tc-MIBI) thyroid scintigraphy in differentiating malignant from benign thyroid nodules with indeterminate cytology using quantitative analysis.

METHOD

One hundred five patients affected by nodular thyroid goiter and with a euthyroid or hypothyroid functional status were prospectively evaluated. All patients had a suspicious nodule ≥15 mm in maximal diameter on US. All nodules were "cold" on (99m)Tc-pertechnetate scintigraphy and had a cytological diagnosis of class III or IV according to the Bethesda system. Planar images of the thyroid were acquired 10 and 60 minutes after (99m)Tc-MIBI administration. All cold nodules were MIBI-positive. Using quantitative analysis, the MIBI washout index (WOind) was calculated as a percentage reduction value of mean MIBI nodular uptake between early (+10 minutes) and late (+60 minutes) scans.

RESULTS

Subdividing the patients into positive and negative for malignancy (either including or excluding patients with Hürthle cell adenoma) and performing receiver operating characterist curve analysis, the optimal WOind cutoff in differentiating malignant from benign follicular lesions was set at -19%. The overall sensitivity and specificity of (99m)Tc-MIBI quantitative analysis in identifying patients with malignant lesions was 100% and 90.9%, respectively. However, after excluding patients with Hürthle cell adenomas from the negative patient group, the overall sensitivity and specificity both reached 100%.

CONCLUSION

The use of MIBI scintigraphy using quantitative analysis in the workup of cold nodules with indeterminate cytology is suggested in order to stratify patient risk for a malignant lesion better, thus reducing the number of patients referred to surgery. Surgical treatment should be planned in those patients with a WOind up to -19%.

Methodological aspects of 99mTc-sestamibi guided biopsy in breast cancer

Purpose

This review aims to discuss the methodological aspects of dedicated molecular breast imaging (MBI) using ^99mTc-sestamibi as radiotracer to guide biopsy of occult or unclear breast lesions on mammography (MG) and ultrasound (US) that are suspicious on MBI (BI-RADS criteria 4 and 5), including its advantages, limitations and future clinical applications.

Methods

Literature search was performed using the PubMed/MEDLINE database and “^99mTc-sestamibi”, “biopsy” and “breast cancer” as keywords. The search was restricted to English language.

Results

There are few studies on ^99mTc-sestamibi guided biopsy methods; to our knowledge, no full studies have yet been reported on clinical validation of this new biopsy procedure. This review describes technical aspects of ^99mTc-sestamibi guided biopsy and discusses the advantages and limitations of this procedure in comparison with MG, US and MRI-guided biopsy.

Conclusions

MBI-guided biopsy appears to be a complementary modality and is principally indicated in the case of occult or unclear breast lesions on MG/US, that are suspicious on MBI. The future indication is in targeted biopsies in patients with large heterogeneous tumours. Further studies are needed to define the accuracy of this biopsy procedure.

The complimentary role of Methoxy-Isobutyl-Isonitrile and hand-held gamma probe in adamantinoma

Adamantinoma is a rare locally aggressive osteolytic tumor that is found 90% of the time in the diaphysis of the tibia with the remaining lesions found in the fibula and long tubular bones. A case of adamantinoma of the tibia is presented. The added value of nuclear medicine investigations in the workup of this patient is described. A three-phase whole body ^99mTc-methylene diphosphonate bone and a whole body ^99mTc-methoxy-isobutyl-isonitrile scans were complimentary in the demarcation of viable bone tumor and the assessment of the remainder of the bone and soft tissue to exclude other sites. Intra-operative assistance with a hand-held gamma probe, guided the biopsy of the most metabolically active tumor tissue. Histology revealed a biphasic tumor composed of epithelial and fibrous components, in keeping with an adamantinoma.

Molecular Analysis by Gene Expression of Mitochondrial ATPase Subunits in Papillary Thyroid Cancer: Is ATP5E Transcript a Possible Early Tumor Marker?

BACKGROUND

Cancer development involves an "injury" to the respiratory machinery (Warburg effect) due to decreased or impaired mitochondrial function. This circumstance results in a down regulation of some of the ATPase subunits of the malignant tissue. The objective of this work was to assess and compare the relative expression of mRNA of mitochondrial ATPase subunits between samples of thyroid cancer and benign nodules.

MATERIAL AND METHODS

Samples from 31 patients who had an operation for PTC at the General Hospital of Mexico were snap-frozen and stored at -70°C. Thirty-five patients who had an operation for benign tumors were also included in the study. mRNA expression levels of alpha, beta, gamma, and epsilon subunits of F1 and "c12" of subunit Fo were determined by real-time RT-PCR (by duplicate), in order to determine if abnormal expression of these genes could partially explain the Warburg effect in papillary thyroid cancer (PTC).

RESULTS

ATP5E transcript alteration (down-expression) was highly associated to PTC diagnosis OR=11.76 (95% confidence interval, 1.245-237.98; p=0.04).

CONCLUSIONS

Relative down-expression of ATP5E transcript was highly associated with PTC diagnosis. This transcript alteration may be used as a tumoral marker in papillary thyroid cancer.

The effect of radiation exposure on multidrug resistance: in vitro and in vivo studies using non-small lung cancer cells

Background

Technetium-99m methoxyisobutylisonitrile (Tc MIBI) is a substrate with the same uptake kinetics as doxorubicin. Multidrug resistance (MDR) is a mechanism that impedes chemotherapy of non-small cell lung cancer (NSCLC). We examined the effect of radiation exposure on MDR in NSCLC and the synergy between an MDR modulator, GG918, and radiation, using ^99mTc MIBI in vitro and doxorubicin in vivo.

Methods

In vitro NSCLC cells (H1299) were exposed to radiation (3-, 6-, and 9-Gy-irradiated groups) alongside a not-irradiated (0 Gy) group. Technetium-99 metastable methoxyisobutylisonitrile (^99mTc MIBI) was administered to cell suspensions at 48 h after irradiation. Cell radioactivity was measured, and C_in/C_out ratios were calculated and compared. NSCLC cells were also subcutaneously transplanted into the left thigh of nude mice, which were subsequently raised for 2 weeks. Two groups of mice were used: mice exposed to irradiation (9-Gy-irradiated) and those that were not (not-irradiated). Doxorubicin was administered through the caudal vein at 48 h after the irradiation. Using an in vivo imaging system, intratumoural photon counts were measured. To determine the synergy between the MDR modulator and 3- or 6-Gy irradiation, the final GG918 concentration was determined: 0.1 μM (N-H, 3-H, and 6-H groups), 0.001 μM (N-L, 3-L, and 6-L groups), and 0 μM (N-0, 3-0, and 6-0 groups). C_in/C_out ratios were calculated and compared among the groups.

Results

C_in/C_out after 6- or 9-Gy irradiation was significantly higher than that of the not-irradiated group (0 Gy). In vivo, fluorescence photon counts were significantly higher in the tumours of 9-Gy-irradiated mice, up to 270 min after administration of doxorubicin, as compared to the not-irradiated mice. The C_in/C_out ratio in the N-H, 3-H, and 6-H groups was significantly higher than that in the N-0, 3-0, and 6-0 groups. There was no significant difference between C_in/C_out in the N-L group and that of the N-0 group. However, the C_in/C_out ratio in the 3-L and 6-L groups was significantly higher than that in the 3-0 and 6-0 groups.

Conclusions

Irradiation decreased MDR in NSCLC cells. In combination with a low-dose MDR modulator, GG918, MDR transport function was synergistically reduced 48 h post-irradiation.

Role of isotope scan, including positron emission tomography/computed tomography, in nodular goitre

Nuclear medicine techniques were first used in clinical practice for diagnosing and treating thyroid diseases in the 1950s, and are still an integral part of thyroid nodules work-up. Thyroid imaging with iodine or iodine-analogue isotopes is the only examination able to prove the presence of autonomously functioning thyroid tissue, which excludes malignancy with a high probability. In addition, a thyroid scan with technetium-99m-methoxyisobutylisonitrile is able to avoid unnecessary surgical procedures for cytologically inconclusive thyroid nodules, as confirmed by meta-analysis and cost-effectiveness studies. Finally, positron emission tomography alone, and positron emission tomography combined with computed tomography scans with (18)F-fluoro-2-deoxy-d-glucose are also promising for diagnosing thyroid diseases, but further studies are needed before introducing them to clinical practice.

(99m)Tc sestamibi as a prognostic factor of response to first-line therapy and outcome in patients with malignant lymphoma

INTRODUCTION

Resistance to chemotherapy poses a major problem in cancer patients. Although of multifactorial origin, some of the implicated mechanisms also interfere with (99m)Tc-MIBI uptake and retention in cancer cells. The aim of the current study was to investigate the prognostic value of baseline (99m)Tc-MIBI imaging in lymphoma.

METHODS

(99m)Tc-MIBI SPECT was performed in 16 patients with Hodgkin lymphoma and 31 with non-Hodgkin lymphoma (NHL) before chemotherapy initiation. Early (20 minutes), late (120 minutes) tumor-to-background (T/B) ratios, and 2-hour (99m)Tc-MIBI washout were calculated. Follow-up data were obtained for a period of 45.5 ± 23.5 months. Study end points were response to first-line chemotherapy, lymphoma-related death (LRD), and time to disease progression.

RESULTS

Of the scintigraphic indices examined, the late T/B ratio correlated best with study end points. A cutoff value of 1.8 determined by receiver operating characteristic analysis discriminated poor from good response and LRD from survival with an accuracy of 87% and 81%, respectively. Kaplan-Meier survivor functions separated by this cutoff differed significantly for both time to disease progression and LRD (P = 0.0001 and P = 0.0015). In the Cox proportional hazards model, the late T/B ratio proved to have an independent and incremental value over clinical prognostic factors (age, lymphoma type, Ann Arbor stage, lactate dehydrogenase levels) and, in NHL patients, over the international prognostic index. Patients with high international prognostic index score could be further stratified into different prognostic categories.

CONCLUSION

The current study indicates that baseline (99m)Tc-MIBI SPECT can provide useful prognostic information in patients with lymphoma, particularly NHL, regarding therapy response and final outcome.

Biological characterization of F-18-labeled rhodamine B, a potential positron emission tomography perfusion tracer

INTRODUCTION

Myocardial infarction is the leading cause of death in western countries, and positron emission tomography (PET) plays an increasing role in the diagnosis and treatment planning for this disease. However, the absence of an (18)F-labeled PET myocardial perfusion tracer hampers the widespread use of PET in myocardial perfusion imaging (MPI). We recently reported a potential MPI agent based on (18)F-labeled rhodamine B. The goal of this study was to more completely define the biological properties of (18)F-labeled rhodamine B with respect to uptake and localization in an animal model of myocardial infarction and to evaluate the uptake (18)F-labeled rhodamine B by cardiomyocytes.

METHODS

A total of 12 female Sprague Dawley rats with a permanent ligation of the left anterior descending artery (LAD) were studied with small-animal PET. The animals were injected with 100-150 μCi of (18)F-labeled rhodamine B diethylene glycol ester ([(18)F]RhoBDEGF) and imaged two days before ligation. The animals were imaged again two to ten days post-ligation. After the post-surgery scans, the animals were euthanized and the hearts were sectioned into 1mm slices and myocardial infarct size was determined by phosphorimaging and 2,3,5-triphenyltetrazolium chloride staining (TTC). In addition, the uptake of [(18)F]RhoBDEGF in isolated rat neonatal cardiomyocytes was determined by fluorescence microscopy.

RESULTS

Small-animal PET showed intense and uniform uptake of [(18)F]RhoBDEGF throughout the myocardium in healthy rats. After LAD ligation, well defined perfusion defects were observed in the PET images. The defect size was highly correlated with the infarct size as determined ex vivo by phosphorimaging and TTC staining. In vitro, [(18)F]RhoBDEGF was rapidly internalized into rat cardiomyocytes with ~40 % of the initial activity internalized within the 60 min incubation time. Fluorescence microscopy clearly demonstrated localization of [(18)F]RhoBDEGF in the mitochondria of rat cardiomyocytes.

CONCLUSION

Fluorine-18-labeled rhodamine B diethylene glycol ester ([(18)F]RhoBDEGF) provides excellent image quality and clear delineation of myocardial infarcts in a rat infarct model. In vitro studies demonstrate localization of the tracer in the mitochondria of cardiac myocytes. In combination, these results support the continued evaluation of this tracer for the PET assessment of myocardial perfusion.

(99m)Tc(N)-DBODC(5), a potential radiolabeled probe for SPECT of multidrug resistance: in vitro study

[(99m)Tc(N)(DBODC)(PNP5)](+) [DBODC is bis(N-ethoxyethyl)dithiocarbamato; PNP5 is bis(dimethoxypropylphosphinoethyl)ethoxyethylamine], abbreviated as (99m)Tc(N)-DBODC(5), is a lipophilic cationic mixed compound investigated as a myocardial imaging agent. The findings that this tracer accumulates in mitochondrial structures through a mechanism mediated by the negative mitochondrial membrane potential and that the rapid efflux of (99m)Tc(N)-DBODC(5) from nontarget tissues seems to be associated with the multidrug resistance (MDR) P-glycoprotein (P-gp) transport function open up the possibility to extend its clinical applications to tumor imaging and noninvasive MDR studies. The rate of uptake at 4 and 37 °C of (99m)Tc(N)-DBODC(5) was evaluated in vitro in selected human cancer cell lines and in the corresponding sublines before and after P-gp and/or MDR-associated protein (MRP) modulator/inhibitor treatment using (99m)Tc-sestamibi as a reference. The results indicated that (1) the uptake of both (99m)Tc(N)-DBODC(5) and (99m)Tc-sestamibi is correlated to metabolic activity of the cells and (2) the cellular accumulation is connected to the level of P-gp/MRP expression; in fact, an enhancement of uptake in resistant cells was observed after treatment with opportune MDR inhibitor/modulator, indicating that the selective blockade of P-gp/MRP prevented efflux of the tracers. This study provides a preliminary indication of the applicability of (99m)Tc(N)-DBODC(5) in tumor imaging and in detecting P-gp/MRP-mediated drug resistance in human cancer. In addition, the possibility to control the hydrophobicity and pharmacological activity of this heterocomplex through the variation of the substituents on the ligands backbone without affecting the P2S2 coordinating sphere makes (99m)Tc(N)-DBODC(5) a suitable scaffold for the preparation of a molecular probe for single photon emission computed tomography of MDR.

SPECT and PET imaging of meningiomas

Meningiomas arise from the meningothelial cells of the arachnoid membranes. They are the most common primary intracranial neoplasms and represent about 20% of all intracranial tumors. They are usually diagnosed after the third decade of life and they are more frequent in women than in men. According to the World Health Organization (WHO) criteria, meningiomas can be classified into grade I meningiomas, which are benign, grade II (atypical) and grade III (anaplastic) meningiomas, which have a much more aggressive clinical behaviour. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are routinely used in the diagnostic workup of patients with meningiomas. Molecular Nuclear Medicine Imaging with Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) could provide complementary information to CT and MRI. Various SPECT and PET tracers may provide information about cellular processes and biological characteristics of meningiomas. Therefore, SPECT and PET imaging could be used for the preoperative noninvasive diagnosis and differential diagnosis of meningiomas, prediction of tumor grade and tumor recurrence, response to treatment, target volume delineation for radiation therapy planning, and distinction between residual or recurrent tumour from scar tissue.

The Role of Routine Whole Volume SPECT Reconstruction in Comparison to Cine Raw Data in the Detection of Extracardiac Uptake on Myocardial Perfusion Scans

The objective of this study was to determine the role of routine whole volume reconstructed single-photon emission tomography (rSPECT) compared to cine raw data to detect extracardiac uptake of Sestamibi (MIBI). In a retrospective study, the myocardial perfusion studies of 426 patients were inspected separately for extracardiac uptake on cine raw data and rSPECT. The acquisition parameters for all the images were done according to departmental protocol. The whole volume SPECT data was selected and processed by HOSEM iterative reconstruction using the HERMES computer software system. The images were assessed by two observers, a student in training and a senior consultant nuclear medicine physician. The overall mean age and standard deviation of the 426 patients at the time of the study was 60 ± 12 years. Statistical analysis was performed using the Kappa and McNemars tests. The clinical significance of the extracardiac uptake was evaluated using hospital folders and /or laboratory results after viewing images. rSPECT detected 25 patients (5.9%) and cine raw data identified 18 patients (4.2%) with extracardiac uptake. All the areas of extracardiac uptake noted on cine raw data were seen on the rSPECT images. Only 21 of the 25 patients had complete 5-year clinical follow-up. The value of the clinical significance of the extracardiac uptake was limited due to the study being retrospective. The proportion of positives identified by rSPECT was significantly larger than those identified by cine raw data (P = 0.0082). Although our study demonstrates that rSPECT is more sensitive than cine raw data in detecting extracardiac uptake, it also shows that there is no benefit in routine whole volume rSPECT in daily clinical practice.

Investigation of blood perfusion and metabolic activity of brain tumours in adults by using 99mTc-methoxyisobutylisonitrile

OBJECTIVES

(i) To examine blood perfusion and metabolic activity of various brain tumours using radionuclide cerebral angiography (RCA) and single-photon emission tomography (SPET) after a single dose of Tc-methoxyisobutylisonitrile (MIBI). (ii) To examine if the inclusion of RCA can improve insight into the relative contribution of tumour perfusion to the uptake of MIBI shown by SPET, and to improve evaluation of tumour biology. (iii) To determine the value and the roles of MIBI in the management of brain tumour patients.

METHODS

Fifty adult patients (38 male, 12 female) with a total of 56 intracranial space-occupying lesions have been included prospectively, 37 of which were newly diagnosed and the remaining with signs of recurrence/rest of earlier resected and irradiated brain tumours. The control group consisted of nine volunteers with no evidence of organic cerebral disease. Scintigraphic examination consisted of a dynamic first-pass study lasting 60 s (3 s/frame) and two SPET studies (60 projections each, 25 s/projection), starting 15 min and 2 h after intravenous injection of MIBI. Regions of interest of the tumour and normal brain tissue were drawn on RCA and both early and delayed SPET slices. The following tumour/brain activity ratios have been calculated: (i) tumour perfusion index (P); (ii) early uptake index (E); (iii) delayed uptake index (D); and(iv) retention index (R). Analogous indices have been calculated from the same examinations performed in controls, reflecting maximal physiologic regional variations of perfusion and uptake in brain tissue.

RESULTS

Mean P of various brain tumours (low-grade gliomas 0.98, anaplastic gliomas 1.14, glioblastoma multiforme 1.20, metastases 1.09, lymphomas 1.08) differ little from each other and do not exceed maximal physiologic regional variations of cerebral perfusion (1.33), with the exception of meningioma (1.87, F=2.83, P=0.015). The receiver operating characteristics curve analysis of P showed that for the cut-off value of 1.45 the sensitivity for distinguishing meningioma from other tumours is 75%, specificity 87%, positive predictive value 33% and negative predictive value 97%. Mean E of malignant brain tumours (8.3, n=31, 23 primary, eight secondary), except anaplastic gliomas (3.5, n=5), differed significantly (P=0.02) from those of benign gliomas (3, n=9) but not from that of meningioma (11.9, n=4). The cut-off value for distinguishing malignant from benign lesions on the basis of E set at 4.8 resulted in sensitivity 67%, specificity 75%, accuracy 70%, positive predictive value 80% and negative predictive value 60%. D and R showed tendency of wash-out of MIBI from meningiomas, but otherwise did not improve the results substantially.

CONCLUSION

Integrated results of RCA and SPET with Tc-MIBI indicate that blood perfusion, blood-tumour barrier permeability and metabolic activity of the tumour are all very important for the resultant uptake shown by SPET. If the perfusion index is less than 1.45, then meningioma can be ruled out. Early SPET is recommendable for distinguishing glioblastoma from low-grade gliomas, as a complement to standard magnetic resonance imaging and/or computed tomography.

Enhanced anti-tumor effects of combined MDR1 RNA interference and human sodium/iodide symporter (NIS) radioiodine gene therapy using an adenoviral system in a colon cancer model

Using an adenoviral system as a delivery mediator of therapeutic gene, we investigated the therapeutic effects of the use of combined MDR1 shRNA and human NIS (hNIS) radioiodine gene therapy in a mouse colon xenograft model. In vitro uptake of Tc-99m sestamibi was increased approximately two-fold in cells infected with an adenovirus vector that expressed MDR1 shRNA (Ad-shMDR1) and I-125 uptake was 25-fold higher in cells infected with an adenovirus vector that expressed human NIS (Ad-hNIS) as compared with control cells. As compared with doxorubicin or I-131 treatment alone, the combination of doxorubicin and I-131 resulted in enhanced cytotoxicity for both Ad-shMDR1- and Ad-hNIS-infected cells, but not for control cells. In vivo uptake of Tc-99m sestamibi and Tc-99m pertechnetate was twofold and 10-fold higher for Ad-shMDR1 and Ad-hNIS-infected tumors as compared with tumors infected with a control adenovirus construct that expressed β-galactrosidase (Ad-LacZ), respectively. In mice treated with either doxorubicin or I-131 alone, there was a slight delay in tumor growth as compared to mice treated with Ad-LacZ. However, combination therapy with doxorubicin and I-131 induced further significant inhibition of tumor growth as compared with mice treated with Ad-LacZ. We have shown successful therapeutic efficacy of combined MDR shRNA and hNIS radioiodine gene therapy using an adenoviral vector system in a mouse colon cancer model. Adenovirus-mediated cancer gene therapy using MDR1 shRNA and hNIS would be a useful tool for the treatment of cancer cells expressing multi-drug resistant genes.

99mTc-MIBI Imaging in the presurgical characterization of thyroid follicular neoplasms: relationship to multidrug resistance protein expression

Recently, thyroid (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) scintiscanning has been proposed in an attempt to preoperatively identify thyroid malignancies, but discrepant results have been reported for oncocytic lesions. The aim of this study was to investigate the usefulness of visual and semiquantitative analyses of (99m)Tc-MIBI scintigraphy for preoperatively characterizing thyroid nodules with indeterminate cytologic diagnoses, segregating in advance nononcocytic variants from those that are oncocytic. This study also aimed to analyze the relationship between (99m)Tc-MIBI images and P-glycoprotein (P-gp)/multidrug resistance-associated protein-1 (MRP1) immunohistochemical expression.

METHODS

Fifty-one consecutive patients with cold thyroid nodules cytologically diagnosed as nononcocytic or oncocytic follicular neoplasm were prospectively studied. Visual and semiquantitative (99m)Tc-MIBI scanning was performed and the diagnoses of the lesions were histologically proven by subsequent thyroidectomy. Immunohistochemical evaluation of P-gp and MRP1 was also performed on surgical samples.

RESULTS

Visual and semiquantitative (99m)Tc-MIBI scintiscans showed a low specificity in preoperatively discriminating malignant oncocytic lesions. In nononcocytic nodules, the semiquantitative method was more accurate than the visual (94.44% and 77.78%, respectively). P-gp protein expression was negative in all thyroid lesions, whereas apical plasma membrane MRP1 expression was found in 78% of the lesions with a negative (99m)Tc-MIBI retention index, compared with 11% of lesions with a positive retention index, correlating most strongly with a negative (99m)Tc-MIBI RI in those cases with strong MRP1 apical expression.

CONCLUSION

Semiquantitative (99m)Tc-MIBI scintigraphy is an adjunctive method to predict preoperatively the malignant behavior of nononcocytic follicular thyroid nodules indeterminate at fine-needle aspiration biopsy, with a potential impact on the definition of their clinical management. Moreover, the good correlation found between immunohistochemical apical expression of MRP1 and the scintigraphic findings supports the (99m)Tc-MIBI results and provides tissue information on the molecular mechanisms responsible for (99m)Tc-MIBI images in thyroid lesions.

99mTc-MIBI brain SPECT as an indicator of the chemotherapy response of recurrent, primary brain tumors

BACKGROUND

Malignant brain tumors carry a pejorative prognosis and necessitate aggressive therapy. Chemotherapy can be used in cases of tumor recurrence. With limited response rate and potential toxicity to chemotherapeutic treatment in patients with recurrent glioma, reliable response assessment is essential.

AIM

To define the place of 99mTc hexakis 2-methoxyisobutylisonitrile (99mTc-MIBI) Single Positron Emission Computed Tomography (SPECT) in monitoring chemotherapy response in recurrent primary brain tumors.

METHODS

In a retrospective analysis, thirty patients were investigated with MIBI SPECT. Imaging was performed 1h after the intravenous injection of 555 MBq of 99mTc-MIBI using a dedicated SPECT system. A MIBI uptake index (UI) was computed as the ratio of counts in the lesion to those in contralateral region. For all patients, we compared changes over time in UI with MRI and clinical data.

RESULTS

The changes in UI agreed well with the clinical and MRI-based assessments in 97% of cases. In 44% of these cases, the scintigraphic response appeared before the MRI response. In instances of treatment failure or rebound, the concordance between scintigraphy and MRI was 52%, and the scintigraphic response appeared before the MRI response in 48% of cases.

CONCLUSION

This study confirms our previous results obtained on a short series of patients with recurrent glioma, concerning the usefulness of MIBI SPECT in prediction of chemotherapy response. Moreover, in cases of tumor progression, we show that MIBI SPECT is an earlier indicator of escape from chemotherapy, an average 4 months before MRI changes.

Functional imaging of multidrug resistance in an orthotopic model of osteosarcoma using 99mTc-sestamibi

PURPOSE

The purpose of this work was the development of an orthotopic model of osteosarcoma based on luciferase-expressing tumour cells for the in vivo imaging of multidrug resistance (MDR) with (99m)Tc-sestamibi.

METHODS

Doxorubicin-sensitive (143B-luc(+)) and resistant (MNNG/HOS-luc(+)) osteosarcoma cell lines expressing different levels of P-glycoprotein and carrying a luciferase reporter gene were inoculated into the tibia of nude mice. Local tumour growth was monitored weekly by bioluminescence imaging and X-ray. After tumour growth, a (99m)Tc-sestamibi dynamic study was performed. A subset of animals was pre-treated with an MDR inhibitor (PSC833). Images were analysed for calculation of (99m)Tc-sestamibi washout half-life (t (1/2)), percentage washout rate (%WR) and tumour/non-tumour (T/NT) ratio.

RESULTS

A progressively increasing bioluminescent signal was detected in the proximal tibia after 2 weeks. The t (1/2) of (99m)Tc-sestamibi was significantly shorter (p < 0.05) in drug-resistant MNNG/HOS-luc(+) tumours (t (1/2) = 87.3 +/- 15.7 min) than in drug-sensitive 143B-luc(+) tumours (t (1/2) = 161.0 +/- 47.4 min) and decreased significantly with PSC833 (t (1/2) = 173.0 +/- 24.5 min, p < 0.05). No significant effects of PSC833 were observed in 143B-luc(+) tumours. The T/NT ratio was significantly lower (p < 0.05) in MNNG/HOS-luc(+) tumours than in 143B-luc(+) tumours at early (1.55 +/- 0.22 vs 2.14 +/- 0.36) and delayed times (1.12 +/- 0.11 vs 1.62 +/- 0.33). PSC833 had no significant effects on the T/NT ratios of either tumour.

CONCLUSION

The orthotopic injection of tumour cells provides an animal model suitable for functional imaging of MDR. In vivo bioluminescence imaging allows the non-invasive monitoring of tumour growth. The kinetic analysis of (99m)Tc-sestamibi washout provides information on the functional activity of MDR related to P-glycoprotein expression and its pharmacological inhibition in osteosarcoma.

Evaluation of respiratory chain failure in mitochondrial cardiomyopathy by assessments of 99mTc-MIBI washout and 123I-BMIPP/99mTc-MIBI mismatch

Cardiomyopathy is one of the main features that determines prognosis in patients with mitochondrial encephalomyopathy. We investigated respiratory chain failure using 99mTc-MIBI- and 123I-BMIPP-SPECT in vivo in five patients with mitochondrial cardiomyopathty. With the lowering of cardiac function, the 99mTc-MIBI-washout rate (WOR) increased, and the 99mTc-MIBI-uptake decreased, conversely. In patients who showed severe cardiac involvement, 99mTc-MIBI-uptake was markedly reduced, and by contrast, 123I-BMIPP-uptake increased (123I-BMIPP/99mTc-MIBI mismatch). There were significant correlations between the WOR on 99mTc-MIBI-SPECT and interventricular septal thickness (IVST) on echocardiography and between WOR and left ventricular ejection fraction (LVEF) on 99mTc-MIBI-SPECT. The increased WOR and decreased uptake of 99mTc-MIBI were reflected by the lowered mitochondrial membrane potential created by mitochondrial respiratory chain whereas 123I-BMIPP/99mTc-MIBI mismatch may be created by the enhanced triglyceride-pool. These nuclear medicine techniques are the potential tools to evaluate the energy state in mitochondrial cardiomyopathy.

Mitochondriotoxic compounds for cancer therapy

One of the hallmarks of cancer cells is their increased resistance to apoptosis induction. Alterations in many apoptosis regulators belonging to the intrinsic pathway confer emerging neoplastic cells with a selective growth advantage in the hostile tumor microenvironment. The realization that those same defects contribute to resistance to radiation and chemotherapeutic agents have prompted the unrelenting search for mitochondria-targeted compounds for the treatment of cancer. Mitochondria play a central role in the process of cell death. They serve as integrators of upstream effector mechanisms. Most importantly, mitochondrial outer membrane permeabilization becomes a commitment point during cell death. Thus, strategies aimed at directly triggering this event by either blocking the activity of antiapoptotic factors or by interfering with vital mitochondrial functions may help to overcome resistance to standard cancer therapy.

A case of malignant pheochromocytoma with early intense uptake and immediate rapid washout of 99mTc-tetrofosmin characterizing the overexpression of anti-apoptotic Bcl-2

Defective apoptotic program due to the overexpression of the anti-apoptotic Bcl-2 protein of the outer mitochondrial membrane may be a cause of the poor response of malignant pheochromocytoma to 131I-MIBG therapy. We report a case of malignant pheochromocytoma which showed early intense uptake and immediate rapid washout of 99mTc-tetrofosmin characterizing the overexpression of anti-apoptotic Bcl-2 and which was refractory to 131I-MIBG therapy.