High-resolution scintimammography improves the accuracy of technetium-99m methoxyisobutylisonitrile scintimammography: use of a new dedicated gamma camera

Abstract

The main disadvantage of technetium-99m methoxyisobutylisonitrile (MIBI) prone scintimammography is its limited sensitivity for T1a and T1b cancers with a size of less than 1 cm. We have developed a high-resolution scintimammographic technique using a gamma camera based on a new concept, namely a position-sensitive photo-multiplier tube. The field of view of this camera, previously known as the SPEM (single photon emission mammography) camera, was 10 cm diameter. Scintimammographic images were acquired in the axial view; each breast was compressed to a thickness of 3-6 cm, modal class 4 cm. When the compressed breast was larger than the field of view, more than one study was performed in order to image the entire gland. Fifty-three patients were studied with high-resolution-scintimammography (HRSM) and Anger camera prone scintimammography (ACPSM). HRSM was performed 70 min after i.v. administration of 740 Mbq of (99m)Tc-MIBI; ACPSM images were acquired 10 and 60 min following the injection. Early 10-min ACPSM images were only evaluated for routine diagnostic purposes, while comparison was carried out between the 60-min ACPSM and 70-min HRSM images. At fine-needle aspiration (FNA) and/or open biopsy, 31 patients showed cancer: 15 T1c, 11 T1b and 5 T1a. In T1a-T1b cancers, the sensitivity of scintimammography was 50% with ACPSM and 81.2% with HRSM (P<0.01). Specificity was 86% with both techniques. HRSM is a promising new technique that improves the sensitivity of (99m)Tc-MIBI scintimammography in tumours sized less than 1 cm without apparently reducing its specificity. We are now working on a larger field-of-view camera.

Development and Characterization of Novel Olumetric Acquisition Orbits With an Application Specific Emission Tomograph for Improved Breast Cancer Detection

“…The custom-made breast phantom is one of several, each with varying sizes and shapes; this particular model has dimensions as given in Table II. The dimensions of these phantoms are within the ranges measured in [25]. The lesiombreast radionuclide concentration ratio was 9.8:1, with an absolute lesion activity concentration of 12.1 /iCi/ml.…”

Nuclear imaging of the breast: Translating achievements in instrumentation into clinical use

“…21,22 Even with this positioning, the distance between the gamma camera and the pendant, uncompressed breast during planar scintimammography was ∼5 cm. As the average thickness of the pendant breast is ∼16 cm, 23 a tumor in the middle of the breast could be 10-15 cm from the collimator face. Conventional gamma cameras equipped with high resolution collimators typically achieve spatial resolutions of 10-15 mm at this distance.…”

Detection and Diagnosis of Breast Diseases

“…On average (50% [40]) for lesions <1 cm such as DCIS particularly, the medially located tumors. In addition, several studies [41][42][43][44][45][46][47][48][49][50][51][52] have pointed out that due to the large FoV of the camera and the bulky collimators, it is diicult to position the camera close to the breast, and thus, imaging breast tissue adjacent to the chest wall may not be possible. This may, ultimately, decrease the spatial resolution of the camera imaging system and thus afect the diagnostic value of the test in detecting such a small lesion size.…”

“…In addition, the smallest lesion sizes that can be detected with these cameras claimed to be 3-3.3 mm [47] compared to 4-5 mm [48] with conventional camera. However, the evidence published to date did not demonstrate a statistically signiicant diference in lesion detection.…”