Is (99m)Tc-sestamibi scintimammography complementary to conventional mammography for detecting breast cancer in patients with palpable masses?

UNLABELLED: The aim of this trial was to evaluate in developing countries from different regions the diagnostic performance of (99m)Tc-sestamibi scintimammography (SM) in palpable breast lesions and to verify the clinical usefulness of a joint evaluation with mammography and SM. METHODS: From 10 countries, a total of 238 patients with palpable breast masses (n = 245) were included in this prospective multicenter trial. Prone SM was performed 10 min and 60-90 min (157 patients) after injection using an isotime acquisition of 10 min. Mammography was assessed by the same dedicated imaging radiologist according to breast imaging reporting and data system (BI-RADS) categories for malignancy and breast density. Masked SM findings and mammography findings were checked for a correlation with histopathology findings for excisional biopsy samples. Diagnostic values for breast cancer detection were calculated per lesion. RESULTS: Histopathology revealed 189 cancerous lesions and 56 benign lesions. The sensitivity and specificity of SM were 0.83 and 0.77, respectively. SM diagnostic values did not depend on the incidence of breast cancer in the country of origin or on the timing of imaging (early vs. delayed scans). On mammography, the technique yielded a sensitivity and specificity of 0.85 and 0.66, with 27 mammograms classified as BI-RADS category 1, 33 as category 2, 5 as category 3, 56 as category 4, and 124 as category 5. Thirty-seven lesions were considered to show increased radiologic density. No significant difference was found in SM diagnostic values among different BI-RADS categories or between the groups with low and high breast density. A sensitivity of 96% was calculated when SM and mammography results were combined, with 75% of all false-negative mammography findings classified as true-positive results by SM. CONCLUSION: SM complements mammography in patients with palpable masses and negative mammography findings.

Radiobiology and stathmokinetics of intestinal crypts associated with patches of Peyer.

The stathmokinetics and radiobiology of intestinal crypts directly adjoining the lymphoid patches of Peyer, have been compared with those of non-patch-associated crypts. Patch crypts contain an additional one to two rings of cells, the Mitotic Index for the whole crypt is higher than in non-patch crypts, and the apparent cell cycle time is insignificantly lower. Using single and split doses of gamma-rays, dose-survival curves were obtained for whole intestinal crypts, from which single-cell survival curves were derived for the clonogenic cells of the crypt. For a single-hit, multitarget, model, the extrapolation numbers of the cell survival curves for patch and non-patch crypts were the same (approximately 35) but the final D0 for cells of the patch crypts was significantly higher (2.1 versus 1.7 Gy). A linear-quadratic fit gave a similar ratio of alpha/beta (approximately 10) for the two curves. For a given level of crypt depletion, the number of clonogenic cells per crypt derived by the use of equal split doses of radiation, was the same for patch and non-patch crypts. This number is a function of the dose regime employed: the higher the level of crypt depletion, the higher the derived number of cells (range 10 to 45, for non-patch crypts).

Topographic variations in the clonogenic response of intestinal crypts to cytotoxic treatments.

In the intestinal crypt microcolony assay, a "surviving fraction" of whole crypts is calculated conventionally by dividing the number of regenerating crypts three to four days after treatment by the number of crypts in untreated animals, both measured around a complete intestinal circumference in transverse sections of gut. We show that in relation to the mesenteric attachment of the gut, crypts in different regions of this circumference differ in their survival characteristics after radiation or mechlorethamine hydrochloride ("HN2"). Crypts associated with Peyer's patches are resistant to both agents (large initial shoulder, shallow slope). The mode of administration of HN2 (IP vs. IV) influences the shape of the crypt survival curve. Differences in size of shoulder and slope affect the estimate of numbers of microcolony-forming cells per crypt (A). For radiation, this number can vary sevenfold, depending on the region of circumference chosen for analysis. Different agents of assay result in radically different values for A.