Reduced Perfusion On Nitrate Enhanced Study Compared To Resting With 99mtc-Sestamibi Imaging For Myocardial Viability

Patients with ischemic heart disease and left ventricular dysfunction need evaluation for myocardial viability. Two cases of myocardial perfusion imaging for viability study are discussed. Viability imaging is performed with 99mTc-Sestamibi (99mTc-MIBI), acquiring images with and without nitrate enhancement. Improvement in perfusion in nitrate enhanced images is suggestive of myocardial viability. In these cases, there was paradox effect showing reduced uptake on nitrate enhanced images than on resting images. Technical factors of equal radiotracer dose in both studies, pre-imaging time and processing were considered. Since no such contributing factor was delineated, it is postulated that phenomena can occur due to differential effects of oral glyceryl triglyceryl trinitrate (GTN) on normal and diseased vessels.

99mTc-MIBI single photon emission computed tomography/computed tomography for the incidental detection of rare parathyroid carcinoma

This study aimed to evaluate the characteristics of parathyroid carcinoma and to validate the diagnostic value of Tc-methoxyisobutylisonitrile (MIBI) single photon emission computed tomography/x-ray computed tomography (SPECT/CT) for differentiating between parathyroid carcinoma and hyperparathyroidism. Four consecutive patients with suspected primary hyperparathyroidism were enrolled in this study and underwent Tc-MIBI SPECT/CT, ultrasonography, enhanced CT, and MRI. Serum parathyroid hormone (PTH) and calcium were measured. All primary and recurrent lesions showed high focal uptake on Tc-MIBI image, whereas metastatic lymph nodes gave false negative results. The serum PTH was 165.14 ± 90.26 pmol/L, which declined rapidly after surgery. One patient with a persistently high PTH (147.5 pmol/L) after surgery presented with multiple lymphadenopathy in the neck. Higher expression of chromogranin A (CgA) further confirmed parathyroid carcinoma as a rare endocrine tumor. Parathyroid carcinoma is thus usually diagnosed incidentally based on nonspecific multiorgan symptoms of hypercalcemia and hyperparathyroidism. Tc-MIBI SPECT/CT may help to localize the parathyroid carcinoma, while MRI is valuable for detecting metastasis. Serum PTH and CgA serve as circulating biomarkers in parathyroid carcinoma, and raised levels of PTH and CgA together with locoregional lymphadenopathy may indicate parathyroid carcinoma. Further studies are needed.

Four-dimensional Computed Tomography (4DCT) for Preoperative Localization of Parathyroid Adenomas

BACKGROUND

Four-dimensional parathyroid computed tomography (4DCT) is a relatively new parathyroid imaging technique that provides functional and highly detailed anatomic information about parathyroid tumors.

OBJECTIVES

To assess the accuracy of 4DCT for the preoperative localization of parathyroid adenomas (PTAs) in patients with biochemically confirmed primary hyperparathyroidism (PHPT) and a history of failed surgery or unsuccessful localization using 99mTc-sestamibi scanning and ultrasonography.

METHODS

Between January 2013 and January 2015, 55 patients with PHPT underwent 4DCT at Hillel Yaffe Medical Center, Hadera, Israel. An initial unenhanced scan was followed by an IV contrast injection of nonionic contrast material (120 ml of at 4 ml/s). Scanning was repeated 25, 60, and 90 seconds after the initiation of IV contrast administration. An experienced radiologist blinded to the earlier imaging results reviewed the 4DCT for the presence and location (quadrant) of the suspected PTAs. At the time of the study, 28 patients had undergone surgical exploration following 4DCT and we compared their scans with the surgical findings.

RESULTS

4DCT accurately localized 96% (27/28) of abnormal glands, all of which were hypervascular and showed characteristic rapid enhancement on 4DCT that could be distinguished from Level II lymph nodes. Surgery found hypovascular cystic PTA in one patient who produced a negative 4DCT scan. All patients had solitary PTAs. The scan at 90 seconds provided no additional information and was abandoned during the study.

CONCLUSIONS

4DCT accurately localized hypervascular parathyroid lesions and distinguished them from other tissues. A three-phase scanning protocol may suffice.

Assessing response using 99mTc-MIBI early after interstitial chemotherapy with carmustine-loaded polymers in glioblastoma multiforme: preliminary results

Introduction. Early signs of response after applying wafers of carmustine-loaded polymers (gliadel) are difficult to assess with imaging because of time-related imaging changes. (99m)Tc-sestamibi (MIBI) brain single-photon emission tomography (SPET) has reportedly been used to reveal areas of cellularity distinguishing recurrent neoplasm from radionecrosis. Our aim was to explore the role of MIBI SPET in assessing response soon after gliadel application in glioblastoma multiforme (GBM). Methods. We retrospectively reviewed the charts on 28 consecutive patients with a radiological diagnosis of GBM who underwent MIBI SPET/CT before surgery (with intracavitary gliadel placement in 17 patients), soon after surgery, and at 4 months. The area of uptake was selected using a volume of interest that was then mirrored contralaterally to obtain a semiquantitative ratio. Results. After adjusting for ratio at the baseline, the effect of treatment (gliadel versus non-gliadel) was not statistically significant. Soon after surgery, however, 100% of patients treated with gliadel had a decreased ratio, as opposed to 62.5% of patients in the non-gliadel group (P = 0.0316). The difference between ratios of patients with radical versus partial resection reached statistical significance by a small margin (P = 0.0528). Conclusions. These data seem to suggest that the MIBI ratio could be a valuable tool for monitoring the effect of gliadel early after surgery.

Clinical utility of 99mTc-Sestamibi scintimammography in the management of equivocal breast lesions

The aim of this study was to assess the utility of 99mTc-sestamibi scintimammography (SM) in patients with suspected primary or recurrent breast cancer. Forty-four (44) breast lesions (17 with suspected recurrence of disease) in 40 patients were included into the study. In these patients, the results of conventional diagnostic methods were equivocal or inconclusive. Twenty-one (21) lesions were palpable and 23 lesions were not. Histological examinations performed during the follow-up revealed malignancy in 24 specimens. SM correctly identified 21 of them, as well as 12 true negatives. There were 8 false-positive studies; therefore, the sensitivity of SM was 87.5%, specificity was 60%, positive predictive value (PPV) was 72.4%, and the negative predictive value (NPV) was 80%. The sensitivity in palpable lesions was 100%; three (3) false negatives, 1 recurrence, and 2 cancers, all of them nonpalpable. In conclusion, SM is useful in equivocal palpable lesions for resolving diagnostic uncertainty after conventional examination, and can limit the number of surgical interventions for benign disease. However, its use in nonpalpable tumors is not recommended.

[Assessment of preoperative localization techniques for patients with primary hyperparathyroidism]

OBJECTIVE

To evaluate the sensitivity and usefulness of 99mTc-sestamibi scintigraphy (SS) and neck ultrasonography (US) as preoperative localization procedures in patients with primary hyperparathyroidism (pHPT).

METHODS

160 patients with proved pHPT in Peking Union Medical College Hospital from June 1983 to June 2002 were studied. There were 107 women(66.9%) and 53 men (33.1%), with a mean age of 38.9 years (10-73 years). 100 patients were underwent SS and 148 patients were underwent US prior to surgery, and the results were compared with operative and histological findings.

RESULTS

The sensitivity of SS and US in localization of the enlarged parathyroid glands was 94.0% and 85.1% respectively, and the positive predictive value of SS and US was 100% and 89.1% respectively, the overall sensitivity was 98.9% by combination of SS and US. In solitary parathyroid adenomas group (n = 145), the sensitivity of SS and US was 93.3% and 84.7% respectively; There was no significant difference (P = 0.428) in sensitivity of SS between the parathyroid glands correctly identified and undetected in classical neck location as compared with ectopic parathyroid glands, whereas significantly (P = 0.026) influenced by the US sensitivity.

CONCLUSIONS

Different sensitivity exit between SS and VS in preoperative localization in patients with pHPT undergoing parathyroidectomy. The combined use of SS and US could increase the sensitivity of localization technique. Ectopic parathyroid had no influence on the sensitivity of 99mTc-MIBI scanning, but decreased the sensitivity of ultrasonography. The size of parathyroid tumors had effects on the sensitivity of ultrasonography. Otherwise, various conditions causing SS false negative were observed. Some interfere factors should be excluded when SS negative results were encountered in clinical practice.

Urinary N-telopeptide levels in multiple myeloma patients, correlation with Tc-99m-sestaMIBI scintigraphy and other biochemical markers of disease activity

Urinary cross-linked N-telopeptide of type I collagen (NTx) has been reported to be a sensitive and specific marker of bone resorption in multiple myeloma (MM). In this study, we measured the levels of NTx in 30 newly diagnosed MM patients and 25 controls. We examined its association with the overall score of skeletal involvement measured by Tc-99m-MIBI scintigraphy and other biochemical markers of bone disease (tumour necrosis factor a (TNF-a), serum calcium and creatinine). We further studied the correlation of NTx with the stage of disease (according to Durie-Salmon criteria) and bone marrow infiltration by plasma cells. High levels of NTx, bone marrow infiltration, TNF-alpha, calcium and creatinine were noted at advanced stages of disease (p < 0.05). NTx and TNF-a were found at significantly higher concentrations in patients with a high overall score (3 and 4) in Tc-99m-sestaMIBI in comparison to a low score (0, 1 and 2; p < 0.05). Positive correlations were found between NTx and TNF-a, as well as between bone infiltration and TNF-a or calcium. In conclusion, NTx is a useful marker for the monitoring of bone resorption in MM and correlates with imaging findings on Tc-99m-sestaMIBI and other biochemical markers of disease activity.

Breast cancer cellular proliferation indexes and 99mTc-sesta Mibi capture: what correlation?

Aim of this study was to verify existing correlations between breast cancer 99mTc-sestaMIBI cells uptake and their cytological characteristics. Forty-five patients with clinically and/or mammographically suspect breast cancer were enrolled. In all patients 99mTc-sestaMIBI scintimammography was performed and malignant lesions were detected in 44 cases and benign in one case. In positive uptake (PU) lesions with diameter <1.5cm, 85.7% showed a high tumor grade (II-III degrees) while in negative uptake (NU) lesions with diameter <1.5cm, 100% showed a low tumor grade (I degrees). In PU lesions, 70% had expressed a high value of Ki 67, while 100% of the NU lesions showed normal values. In this series, tumor diameter does not play a basic role, while the correlations between uptake and the histological grade (G) and/or cellular kinetics (Ki67) seem to be more important. Further studies are needed to confirm our present results.

Detection of restenosis after percutaneous transluminal coronary angioplasty using the exercise treadmill test and technetium 99m-sestamibi scintigraphy

BACKGROUND

The detection of myocardial ischemia after percutaneous transluminal coronary angioplasty (PTCA) is important because 30-50 per cent of the patients will develop restenosis within 6 months. Symptoms of chest pain and exercise stress test (EST) have shown to be less sensitive for detection of ischemia than exercise Technetium-99m Sestamibi (Tc-99m MIBI). The purpose of this study was to compare the sensitivity and specificity of chest pain, EST and Tc-99m MIBI with coronary angiography (CAG).

METHOD

Tc-99m MIBI with SPECT imaging was performed at months 1, 3 and 6 and CAG was repeated 6 months after successful PTCA. Earlier Tc-99m MIBI and CAG were performed in patients with recurrent angina pectoris or suspected restenosis.

RESULTS

Forty six patients (M 29, F 17) who had undergone successful angioplasty were prospectively enrolled. Their mean age was 61 +/- 19 yrs. Eighty eight lesions (LAD63%, LCX34%, RCA19%) were performed. Lesion characteristics were type A in 9 per cent, type in B 30 per cent and type C in 61 per cent. Fifty four per cent of PTCA were performed for single vessel disease and 46 per cent for multivessel disease. The mean duration of time between PTCA and follow-up CAG was 6.1 +/- 2.7 months. We detected restenosis from CAG in 58 per cent of the cases. The Tc-99m MIBI had higher sensitivity to detect restenosis than anginal pain (85.0% vs 39.4% p < 0.005) or EST (85.0% vs 63.6% p < 0.05) when compared with CAG. The overall accuracy of Tc-99m MIBI for the detection of restenosis was 80 per cent.

CONCLUSION

Tc-99m MIBI with SPECT imaging constitutes a better means than symptoms or exercise test to detect restenosis after successful coronary angioplasty.

Non-131I-scintigraphy in the treatment and follow-up of thyroid cancer. Single-photon-emitters or FDG-PET?

With respect to further therapeutic options, whole-body 131I scintigraphy (WBS) is the most important functional imaging technique during treatment and follow-up of differentiated thyroid cancer. But in many patients, thyroid cancer tissue does not concentrate 131I and can therefore not be localized using WBS. In addition to morphologic techniques, which have a low specificity in many cases, other methods are necessary to localize tumor tissue in these patients. Besides 201Tl, which has been used initially as a tumor-seeking agent, sestamibi, tetrofosmin and 18F-DG for PET imaging have been evaluated in differentiated thyroid carcinoma. This paper summarizes the clinical impact of functional imaging with tracers besides 131I. In direct comparison, 18F-DG-PET has the highest sensitivity, which exceeds 80% in cases with negative WBS. If available, this method should be considered in all patients suffering from differentiated thyroid cancer with suspected recurrence and/or metastases, particularly in cases with elevated thyroglobulin values and negative WBS. But also 99mTc-labeled tracers can be used to detect tumor tissue with a sufficient sensitivity. In medullary thyroid cancer, which presents frequently with diagnostic difficulties, 111In-octreotide, 99mTc-(V)-DMSA, 131I/123I-mIBG, and anti-CEA can be used, in addition.

Radionuclide techniques for the assessment of myocardial viability

Images

Comparison of technetium-99m-sestamibi scintimammography with contrast-enhanced MRI for diagnosis of breast lesions

Scintimammography using 99mTc-sestamibi and contrast-enhanced MRI were performed to determine the diagnostic accuracy of either method in the diagnostic workup of patients suspicious for breast tumors.

METHODS

Fifty-six patients (42 with indeterminate mammograms) underwent preoperative prone planar scintimammography and pre- and postcontrast-enhanced MRI. Visually determined signal increase after application of Gd-DTPA was compared with visually scored sestamibi uptake, and the diagnoses of both methods were correlated with the final histopathologic results.

RESULTS

Overall, sensitivity and specificity of scintimammography for diagnosing breast cancer were 88% and 83%, respectively. In the subgroup of patients with indeterminate mammograms, sensitivity was 79% and specificity was 83%. MRI readings provided a higher sensitivity (91% with respect to all patients and 89% with respect to patients with indeterminate mammograms), but a considerably lower specificity (52% in both groups) due to contrast-enhancement in different benign lesions.

CONCLUSION

Due to its considerably higher specificity, scintimammography rather than MRI may be suitable to reduce the number of breast biopsies which yield benign results. Thus, this method may be suggested as the preferable tool in the diagnostic workup of patients with indeterminate mammographic findings.

Clinical outcome of patients evaluated with emergency centre myocardial perfusion SPET for unexplained chest pain

The clinical outcome of 68 patients with unexplained chest pain triaged with emergency centre (EC) SPET myocardial perfusion imaging (MPI) was assessed at 9 month follow-up. Based on clinical presentation and EC-MPI, 63% (43/68) of patients were discharged from the EC; 84% (36/43) of these patients reported no further symptoms at follow-up. There were no adverse clinical events in patients with totally normal EC-MPI.

Demonstration of popliteal artery entrapment on leg muscle scintigraphy with 99mTc MIBI and single photon emission tomography

Popliteal artery entrapment is difficult to diagnose even at surgery. Early diagnosis is important as the prognosis is better if detected before the onset of complications. There is no sensitive method for the evaluation of this condition. We describe three cases detected by a new technique using 99mTc methoxy isobutyl isonitrile (MIBI) with single photon emission tomography. The scintigraphic features of entrapment and the advantage of MIBI leg scintigraphy over other methods are discussed.