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The aim of this study was to compare 201Tl-chloride and 99Tc(m)-sestamibi (MIBI) SPET brain imaging for differentiating brain lymphoma from other intracranial lesions in AIDS patients. Both studies were performed on the same day in 17 AIDS patients with intracranial enhancing lesions on either CT or MRI. Eleven patients underwent brain biopsy and six patients were followed clinically. We calculated the radiopharmaceutical uptake ratio of the lesion to that on the contralateral side with the guidance of CT or MRI findings. Ratios of 1.5 or more were considered to represent malignant lesions and ratios < 1.5 were considered to represent benign lesions. Biopsy revealed four cases of lymphoma, four cases of toxoplasmosis and two cases of progressive multi-focal leukoencephalopathy; one biopsy yielded necrosis. Both the MIBI and 201Tl studies yielded no false-negative cases of lymphoma (sensitivity 100%). Of the 13 non-lymphoma cases, the 201Tl studies showed seven true-negative cases (specificity 54%) and the MIBI studies showed nine true-negative cases (specificity 69%). The biopsies of the false-positive cases (toxoplasmosis) showed a pattern of healing after medical treatment. We conclude that MIBI is more helpful than 201Tl because of higher specificity and equal sensitivity. The medical treatment of toxoplasmosis is a cause of false-positive 201Tl and MIBI studies.

Planar scintimammography with 99 Tc m -sestamibi ( 99 Tc m -MIBI) has been shown to be useful in diagnosing breast carcinoma. The aim of this study was to compare single photon emission tomography (SPET) and planar imaging for scintimammography with 99 Tc m -MIBI in the detection of primary breast cancer and axillary lymph node involvement. Sixty-three females with mammographically suspicious lesions and 12 controls were evaluated. Dynamic images were acquired commencing immediately after the injection of the radiopharmaceutical, followed by multiple planar images in the supine and prone positions plus SPET supine imaging. A final histopathological diagnosis was achieved after surgery. A total of 66 breast lesions were considered. No focal uptake of 99 Tc m -MIBI was observed in the breasts or axillas of the controls. In the patients with breast cancer, the sensitivity was 92.9% (39/42) for SPET, 71.4% (30/42) for supine and 85.7% (36/42) for prone planar imaging, respectively; the specificity was 87.5% for SPET and 91.6% for the planar scans. Metastatic axillary lymph node involvement was seen in 19 patients: the sensitivity was 84.2% (16/19) for SPET and 63.2% (12/19) for planar images; the specificity was 91.3% and 95.7% respectively. Our results confirm the high diagnostic accuracy of 99 Tc m scintimammography in the diagnosis of breast cancer, and suggest that SPET is more sensitive than planar images, especially in detecting axillary lymph node involvement.

Neoadjuvant chemotherapy (NACT) is the treatment of choice in patients (pts) with locally advanced (LABC) and inflammatory breast cancer (IBC). To evaluate the role of Tc-99m sestamibi imaging in the prediction of response to NACT and in the in vivo functional detection of intrinsic or acquired chemoresistance, 24 female pts with LABC (n=21) or IBC (n=3) were prospectively studied. Tc-99m scintimammography was performed 1-3 days before treatment (first) and 2-5 days after the completion (second) of NACT (epirubicin and cyclophosphamide for LABC and doxorubicin and vinorelbine for IBC). Three planar images (2 lateral prone and one anterior supine, 10 min/each) were obtained 10 min postinjection and a lateral prone image (10 min) of the affected breast (B) was obtained at 4 It. To calculate the tumor to normal B ratio (TBR), 2 identical irregular regions of interest (ROIs) were drawn around the tumor (T) and in adjacent ipsilateral normal B on both early (E) and delayed (D) prone lateral images. The TBR was obtained as the ratio of the mean counts per pixels in the 2 ROIs. Then Tc-99m sestamibi retention index (RI) in the T was determined by dividing the D-TBR by the E-TBR. Afterwards, NACT response was assessed pathologically or clinically in inoperable disease. Scintigraphic sensitivity for correct prediction of T presence after NACT was 81% (17/21), whereas specificity for correct prediction of T absence was 100% (3/3). In LABC, 3 patients had a pathological complete response: first RI was high (>0.56) in all 3, while no T uptake was visible on the second scintigraphy. Eighteen patients did not show a pathological complete response: in 5, both first and second RI were low (less than or equal to0.56); 9 had high first RI but low second; 4 had high first RI and no T detected on the second scan. In IBC, the only patient with a clinical complete response had both first and second RI high, whereas the 2 non-responsive pts had both first and second RI low. These results indicate that Tc-99m sestamibi scintimammography can predict LABC and IBC response to NACT. The scintigraphy protocol, including 2 studies before and after NACT, is useful for detecting intrinsic and acquired chemoresistant BC in vivo, which is important for planning therapy and predicting prognosis.

We examined the relevance of a pre-treatment single static view 99m Tc-sestamibi scintimammography and expression of multidrug resistance proteins as predictors of response to neoadjuvant chemotherapy for invasive breast cancer. Forty-five patients affected by primary breast cancer underwent clinical examination, mammography, sonography, 99m Tc-sestamibi scintimammography, and biopsy for histopathological diagnosis before neoadjuvant chemotherapy. Expression of MDR1 and MRP mRNA were determined by RT-PCR on fine-needle aspirations. Following completion of anthracycline-based chemotherapy, clinical, mammographic, sonographic and pathological responses were determined. 99m Tc-sestamibi scintimammography predicted the reduction of tumor size measured by sonography and the pathological response according to Sataloff classification (p

PURPOSE Since we have previously shown that the efflux rate of technetium 99m (99mTc) sestamibi, a transport substrate of P-glycoprotein (Pgp), is directly correlated with Pgp levels in untreated breast carcinoma, we tested whether tumor clearance of 9mTc-sestamibi may be predictive of therapeutic response to neoadjuvant chemotherapy in patients with locally advanced breast cancer. PATIENTS AND METHODS Thirty-nine patients with stage III disease, median tumor diameter 5.8 cm (range, 3 to 10) were enrolled onto this prospective clinical trial and underwent 99mTc-sestamibi scan before neoadjuvant chemotherapy. Patients were injected intravenously (i.v.) with 740 MBq of 99mTc-sestamibi; a 15-minute dynamic study was performed, and static planar images were obtained at 0.5, 1, 2, and 4 hours. The time to half clearance of 99mTc-sestamibi was calculated in each patient from decay corrected time-activity curves using a monoexponential fitting. Patients were treated with epirubicin 150 mg/m2 i.v. every 2 weeks for three courses and then underwent surgery within 3 weeks from the completion of chemotherapy. Residual tumor was assessed by pathologic examination of mastectomy specimens. RESULTS Seventeen of 39 patients showed a rapid tumor clearance of 9mTc-sestamibi (time to half clearance [t1/2] < or = 204 minutes) and 15 of these 17 (88%) showed a highly cellular macroscopic residual tumor at histology that indicated lack of tumor response to neoadjuvant chemotherapy. In contrast, only eight of 22 (36%) with prolonged retention of 99mTc-sestamibi (t1/2 > 204 minutes) showed residual macroscopic tumor at histology (Fisher's exact test, P < .01). CONCLUSION A rapid tumor clearance of 99mTc-sestamibi may predict lack of tumor response to neoadjuvant chemotherapy with drugs affected by the multidrug-resistant phenotype in patients with locally advanced breast carcinoma.