继发性甲状旁腺功能亢进的99Tcm-MIBI双时相显像

目的评价９９Ｔｃｍ甲氧基异丁基异腈（ＭＩＢＩ）双时相显像法在肾性继发性甲状旁腺功能亢进（ＳＨＰ）患者中的诊断价值。方法２０例因慢性肾功能衰竭行血液透析患者,临床诊断为ＳＨＰ,均行双时相法９９ＴｃｍＭＩＢＩ甲状旁腺显像。运用甲状旁腺／甲状腺（ＰＴ／Ｔ）比值及甲状旁腺指数（ＰＴＩ）观察阳性病灶对ＭＩＢＩ的清除。３例行颈部探查术并作甲状旁腺自体移植。结果８例显像阳性,其中３例手术摘除９枚甲状旁腺,均经病理证实为增生。９９ＴｃｍＭＩＢＩ显像发现其中的８枚,其灵敏度为８８９％。在透析年限长、甲状旁腺素分泌高的患者中,有更高的阳性率。发现有３种ＭＩＢＩ清除类型。结论９９ＴｃｍＭＩＢＩ双时相显像在ＳＨＰ患者中有较高的定位诊断价值。阅片时应考虑病灶清除ＭＩＢＩ的多样性,以免漏诊     

Dobutamine modulated Tc-99m MIBI scintigraphy in secondary hyperparathyroidism in uremic patients

The aim of this study was to determine if low-dose dobutamine infusion can enhance Tc-99m methoxy isobutyl isonitrile (MIBI) uptake of hyperfunctioning parathyroid glands of patients with secondary hyperparathyroidism (SHP).We studied 24 patients with chronic renal failure and SHP. Median age of the sample was 47.5 years. A single-tracer, double-phase technique was performed, acquiring planar images of the neck and thorax after the injection of 740 to 1110 MBq (20-30 mCi) of Tc-99m MIBI. After 2 to 7 days, the study was repeated after the infusion of low-dose dobutamine of 2.0 microg . kg . min for 60 minutes. The scan was considered positive for hyperfunctioning parathyroid tissue when an area of increased uptake that persisted on late imaging was found. Parathyroid-to-thyroid count rates (PT/T) were calculated for each abnormal focus.Hyperplasic parathyroid tissue was confirmed in 12 of 24 patients who underwent neck surgery whereas the remaining group had persistent or worsening disease, verified by clinical follow-up between 6 and 25 months after the nuclear studies (median: 12 months).An MIBI baseline study was positive in 21 of 24 patients (87%), whereas the dobutamine study was positive in all patients. Thirty-five abnormal foci were seen on baseline MIBI studies and 43 on dobutamine scans (1.46 +/- 1.02 vs. 1.79 +/- 0.88, mean +/- SD, respectively, P = 0.043). Dobutamine PT/T ratios were significantly higher than those from the baseline study (1.49 +/- 0.30 vs. 1.38 +/- 0.28, mean +/- SD, respectively, P = 0.0002, n = 43).We concluded that low-dose dobutamine Tc-99m MIBI scintigraphy has the potential of enhancing tracer uptake and retention in patients with SHP.     

Primary osteogenic sarcoma of breast detected on Tc-99m MIBI scintigraphy and Tc-99m MDP skeletal scintigraphy

A 64-year-old woman presented with a painless breast mass. Tc-99m methoxyisobutylisonitrile scintigraphy of both breasts showed a local area of abnormal uptake in the left breast in 5 min and 2 h. A skeletal scan showed very intense concentration of activity in the primary breast tumor in the left breast. A left mastectomy and an axillary dissection were performed. The predominant histologic type of the mass was an osteosarcoma, and the diagnosis of a primary osteogenic sarcoma of the breast was made. Primary osteogenic sarcoma of the breast is rare and represents less than 1% of all primary breast malignancies.     

Bone uptake of Tc-99m MIBI in patients with hyperparathyroidism

Objective

The study aimed to investigate the incidence of bone uptake of tracer on Tc-99m MIBI imaging and explore its influencing factors and significance for diagnosis of metabolic bone disease (MBD) in patients with hyperparathyroidism (HPT).

Methods

Seventy-nine consecutive patients with histopathologically confirmed HPT (63 primary and 16 secondary) who had preoperative Tc-99m MIBI imaging were retrospectively evaluated. Serum calcium (Ca), phosphorus (P), and intact parathyroid hormone (iPTH) were measured for all patients, and serum alkaline phosphatase (ALP) was measured for 62 patients. Of the 79 patients, 50 underwent bone mineral density (BMD) examination and 30 underwent bone scintigraphy. The incidence and characteristics of abnormal bone uptake of MIBI were recorded. Mann–Whitney test was performed to determine if serum iPTH, Ca, P, ALP, and BMD were different between the patients with and without MIBI bone uptake. Logistic regression analysis was used to analyze the factors that influence the bone uptake of MIBI. The concordance rate between Tc-99m MIBI imaging and bone scintigraphy in delineating MBD was calculated.

Results

Tc-99m MIBI imaging disclosed the abnormal bone uptake of tracer in 22 (27.8 %) patients. Of them, 19 showed diffusely increased activity in skeleton, 2 showed focal uptake in brown tumors, and one showed both above patterns. Patients with bone uptake MIBI had higher level of serum iPTH (Z = ?4.34, P < 0.001) and ALP (Z = ?3.50, P < 0.001) than those without bone uptake. Logistic regression analysis also showed that bone uptake of MIBI was correlated with serum iPTH (OR = 4.42, P < 0.001) and ALP (OR = 3.21, P = 0.002). Among the 30 patients that underwent bone scintigraphy, 76.7 % patients showed signs of MBD, and the concordance rate between Tc-99m MIBI imaging and bone scintigraphy was 60 % for detecting MBD.

Conclusions

Bone uptake of MIBI in patients with HPT is commonly related to a high level of iPTH and ALP; it probably reflects an active stage of MBD, and it should be monitored during the conventional Tc-99m MIBI scintigraphy.     

False-negative Tc-99m MIBI scintigraphy in histopathologically proved recurrent high-grade oligodendroglioma

Tc-99m MIBI is a small lipophilic radioligand that enters cells by diffusion and is preferentially trapped in mitochondria. As a result of the high mitochondrial activity in tumors, Tc-99m MIBI accumulates significantly more in tumor tissue compared with normal tissues. Accordingly, Tc-99m MIBI has been used successfully to visualize primary, metastatic, and recurrent tumor. In brain tumors, Tc-99m MIBI SPECT has been shown to identify tumor recurrence after treatment in high-grade gliomas. In this report, early (30 minutes after injection) and delayed (4 hours after injection) Tc-99m MIBI SPECT did not visualize a histopathologically proved recurrent high-grade oligodendroglioma. Increased vascular supply, disruption of the blood-brain barrier, high-grade cancer, and viability of tumor cells are decisive factors related to increased Tc-99m MIBI uptake in brain tumors. However, the authors' results suggest that still other mechanisms may be involved in Tc-99m MIBI accumulation, which may account for false-negative imaging in brain tumors.     

Tc-99m MIBI scintigraphy in a patient with primary and metastatic malignant melanoma

Malignant melanoma is a rare malignant tumor arising within the melanocytes of the skin. The authors report a case of primary and metastatic malignant melanoma revealed with Tc-99m MIBI in one patient. Tc-99m MIBI images showed uptake in possible malignant melanoma skin lesions of the left calf and great toe of a 73-year-old man. Malignant melanomas (primary and metastatic) were diagnosed on excisional biopsies. Tc-99m MIBI scintigraphy might be useful not only in the diagnosis of possible primary malignant melanoma lesions but also in the diagnosis of metastatic or recurrent disease.     

Correlation between P-glycoprotein (P-gp) expression in parathyroid and Tc-99m MIBI parathyroid image findings

The major factor to influence localization of parathyroid adenomas is tumor size. P-glycoprotein (P-gp) expression in parathyroid adenomas has been considered to be an another possible factor to influence localization of parathyroid adenomas because false-negative studies have been reported with large tumors and true-positives reported with very small tumors in previous studies. The aim of this study was to characterize Tc-99m MIBI uptake and retention by parathyroid adenomas and to correlate this with cell surface expression of P-gp. Sixteen patients with parathyroid adenoma (larger than 1.5 gm) underwent dual-phase (10min and 2hr) Tc-99m MIBI parathyroid image immediately before parathyroid exploration. Tissues were obtained from normal and abnormal parathyroid glands and from the thyroid gland. Immunohistochemistry (IHC) was obtained with monoclonal antibodies to identify P-gp expression in all tissues. All of the 16 parathyroid adenomas and 32 normal control specimens (16 normal parathyroid and 16 normal thyroid specimens) were submitted for P-gp detection by IHC. The dual-phase Tc-99m MIBI parathyroid image accurately localized 14 parathyroid adenomas, but not the remaining 2 adenomas. The 14 parathyroid adenomas with significant Tc-99m MIBI uptake in delayed 2hr images revealed negative P-gp expression, but the 2 adenomas without significant Tc-99m MIBI uptake, as well as normal parathyroid and normal thyroid specimens, revealed positive P-gp expression when evaluated by IHC. Not only the size of parathyroid adenomas, but also significant P-gp expression limited the sensitivity of dual-phase Tc-99m MIBI parathyroid image to localize parathyroid adenomas before operation.     

Ectopic parathyroid adenoma with Tc-99m MIBI washout: role of SPECT

The authors present a case of a 71-year-old woman with clinical and biochemical features of primary hyperparathyroidism and a history of right pneumonectomy. An ultrasound scan did not demonstrate any abnormality. A planar Tc-99m methoxyisobutylisonitrile (Tc-99m MIBI) scan showed an area of minimally increased uptake within the right hemithorax. However, unlike most adenomas, this demonstrated washout similar to the thyroid at 90 minutes and 3 hours. Subsequent SPECT imaging clearly showed the lesion in the superior right hemithorax. A CT scan and angiogram confirmed the presence of this mass. After surgery, histology confirmed the diagnosis of a parathyroid adenoma. Postoperatively, the calcium and PTH levels returned to normal.     

Tc-99m MIBI imaging in malignant fibrous histiocytoma

The authors report a case of malignant fibrous histiocytoma of the left forearm demonstrated by Tc-99m MIBI imaging. The tumor originated in the soft tissue of the forearm; no obvious bone invasion or metastasis was detected scintigraphically or radiologically.     

Double-phase Tc-99m MIBI scintigraphy as a therapeutic predictor in patients with non-Hodgkin's lymphoma

PURPOSE: Tc-99m MIBI is a promising agent for the functional characterization of P-glycoprotein expression and the prediction of therapeutic outcome in human tumors. The purpose of this study was to determine whether tumor clearance of Tc-99m MIBI may have a predictive value in the clinical outcome in patients with non-Hodgkin's lymphoma. METHODS: Seventeen patients with histologically proved non-Hodgkin's lymphoma underwent Tc-99m MIBI scintigraphy before starting chemotherapy. Early and late images were obtained after the injection of 740 MBq (20 mCi) Tc-99m MIBI. Tumor-to-normal soft tissue ratios were measured on early and late images, and the percentage retention (%R) was calculated. These findings were correlated with other prognostic factors. RESULTS: Of all 40 tumor lesions, 22 (55%) showed Tc-99m MIBI tumor uptake, whereas the other 18 (45%) lesions had no uptake. According to the location, the diagnostic accuracy of Tc-99m MIBI scans was 66.7% (12 of 18) for lesions of the head and neck, 66.7% (8 of 12) for those of the chest, and 20% (2 of 10) for those of subdiaphragmatic regions (P = 0.037). The mean %R of complete responders was 91.8 +/- 14.8% and for partial responders or nonresponders it was 65.4 +/- 17.7% (P = 0.014). The %R of Tc-99m MIBI showed a significant negative correlation with the serum lactate dehydrogenase level (r = -0.757), the score of the international prognostic index (r = -0.643), and the Ann Arbor stage (r = -0.733). CONCLUSION: The slow tumor clearance of Tc-99m MIBI can predict a good response to chemotherapy in patients with non-Hodgkin's lymphoma and differentiate responding and nonresponding tumors early in the course of chemotherapy.     

Cervical paraganglioma mimicking a parathyroid adenoma on Tc-99m sestamibi scintigraphy

A 32-year-old man with a clinical and biochemical profile suggestive of primary hyperparathyroidism presented with a soft tissue mass on the left side of the neck. Multiphasic planar and SPECT Tc-99m sestamibi (MIBI) scintigraphy showed focally increased tracer concentration in the mass. Subsequent histopathology and immunostaining identified the mass as a parathyroid hormone-secreting cervical paraganglioma, indicating that this tumor should be considered in the differential interpretation of MIBI concentration in the neck.     

Optimal pinhole techniques for preoperative localization with Tc-99m MIBI for primary hyperparathyroidism.

PURPOSE: Technetium-99m-labeled 2-methoxyisobutylisonitrile (Tc-99m MIBI) has been used extensively to localize parathyroid adenomas before operation. Imaging techniques vary widely, and the aim of this study was to determine the optimal time of delayed imaging and the value of routine correlative pertechnetate thyroid imaging. MATERIALS AND METHODS: In this study, preoperative parathyroid localization was performed using pinhole anterior and oblique images (15 minutes and 2 and 4 hours after injection) with correlative pertechnetate thyroid images. Ninety-seven patients underwent dual- or triple-phase Tc-99m MIBI imaging and correlative pertechnetate thyroid imaging before surgery. Two nuclear medicine physicians blinded to the surgical findings interpreted all available images and various Tc-99m MIBI image combinations at 15 minutes alone; 15 minutes and 2 hours, 15 minutes and 4 hours; and 15 minutes and 2 and 4 hours each with and without correlative pertechnetate thyroid imaging. RESULTS: Ninety parathyroid adenomas were detected in 86 patients. The optimal results were achieved with 15-minute and 2- and 4-hour Tc-99m-MIBI images, with correlative thyroid scans resulting in a sensitivity rate of 88%. Fifteen-minute and 2-hour Tc-99m-MIBI images and correlative thyroid scans and 15-minute and 4-hour Tc-99m MIBI images and correlative thyroid scans produced similar results (sensitivity rate, 86% and 83%, respectively; P = not significant). Compared with all Tc-99m MIBI image combinations alone, the addition of the routine correlative thyroid scan significantly improved sensitivity and also improved reporter confidence in 45% of studies. CONCLUSIONS: Of the pinhole techniques compared, 15-minute and 2-hour Tc-99m MIBI images with correlative thyroid scanning may be the preferred imaging protocol, because this yields results similar to imaging for as long as 4 hours after injection in a shorter, more logistically acceptable imaging time.     

Protein-losing enteropathy detected on Tc-99m HSA and Tc-99m MDP scintigraphy

The authors describe a patient with protein-losing enteropathy in whom abnormal intestinal accumulation of tracer occurred during Tc-99m human serum albumin scintigraphy. Abnormal leakage of the radiotracer was observed in the left upper abdomen and was confirmed by Tc-99m MDP scintigraphy. Both Tc-99m HSA scintigraphy and Tc-99m MDP scintigraphy are useful in the detection of protein-losing enteropathy.