Edwin Szeto

Dual-time-point (18)F-FDG-PET/CT imaging in the assessment of suspected malignancy.

Introduction (purpose of the study): The objective of this study was to assess whether dual‐time‐point 18F‐fluoro‐2‐deoxyglucose (18F‐FDG)‐PET/CT imaging improved the evaluation of suspected malignancy and if there was any resulting change in management.

FDG positron emission tomographic imaging of a large abdominal aortic aneurysm.

A 77-year-old man was examined by his local physician because of bilateral pedal edema. Routine radiographs showed a large pulmonary mass at the apex of the right upper lobe. Follow-up computed tomographic (CT) scans of the chest, abdomen, and pelvis showed the lung mass but also a 9.2-cm infrarenal abdominal aortic aneurysm (AAA). The patient was referred for a whole-body F-18 fluorodeoxyglucose positron emission tomography (FDG PET) scan to stage the presumed non-small-cell lung cancer before surgery. The PET scan showed glucose-avid foci consistent with stage IV non-small-cell lung cancer, but it also clearly demonstrated the AAA. The AAA was seen as an area of ametabolism, corresponding to a mural thrombus, and an inverted Y of intraluminal FDG that outlined the distal aorta and the iliac bifurcation.

Successful internal mammary visualization with periareolar injections of Tc-99m antimony sulfur colloid in sentinel node breast lymphoscintigraphy.

Purpose: The subareolar and periareolar injection techniques result in higher detection rates and do not require tumor localization in impalpable lesions when compared with the peritumoral technique. One of the main criticisms, however, is the widely reported inability to detect internal mammary nodes. This contrasts with our clinical experience using Tc-99m antimony sulfur colloid, in which internal mammary nodes are commonly seen. Methods: A retrospective analysis of 241 patients over 38 months was performed to investigate the ability of our periareolar injection technique to detect internal mammary lymph node drainage in breast cancer sentinel node lymphoscintigraphy. Four injections of 5 to 10 MBq (0.14–0.27 mCi) Tc-99m antimony sulfur colloid were administered on the day of surgery followed by massage and imaging. The radioisotope was suspended in 0.1 mL with a 0.5-mL air lock. Each injection was performed over 2 seconds with a 25-gauge needle at a depth of 1.1 to 1.3 cm. Patients whose records could not be retrieved or who underwent an injection technique apart from periareolar or peritumoral were removed from the analysis. Results: One hundred thirty-three patients underwent the periareolar technique, 72 patients underwent the peritumoral technique, and 36 patients were excluded from the analysis. Internal mammary drainage was seen in 24 of 133 (18.0%) patients, of which 12 (9%) were seen only in the internal mammary chain. This is much higher than previous studies quoting 0.0% to 4.3% and is similar to previously reported rates using the peritumoral technique. Conclusions: Our periareolar injection technique using Tc-99m antimony sulfur colloid is able to detect internal mammary lymph nodes in at least 18.0% of patients.

Coincidence detection Fdg Pet in the management of oncological patients: attenuation correction versus non-attenuation correction

The aim of this study was to determine if attenuation correction (AC) in a dual-head, coincidence, positron emission tomography imaging system (Co-PET) improved image quality, lesion detection, patient staging and management of various malignant neoplasms, compared to non-attenuation corrected (NAC) images. Thirty patients with known or suspected malignant neoplasms underwent fluorodeoxyglucose (FDG) Co-PET, which was correlated with histopathology, computed tomography (CT) and other conventional imaging modalities and clinical follow-up. The number and location of FDG avid lesions detected on the AC images and NAC Co-PET images were blindly assessed by two independent observers. Semi-quantitative grading of image clarity and lesion-to-background quality was performed. This revealed markedly improved image clarity and lesion-to-background quality in the AC versus NAC Co-PET images. AC Co-PET was statistically superior to NAC Co-PET in relation to lesion detection (P<0.01) and tumour staging (P<0.01). NAC Co-PET demonstrated 51 of the 65 lesions (78%) detected by AC Co-PET. AC Co-PET altered tumour staging in five additional patients (16%) compared to NAC Co-PET. Management was altered in two of these five patients.

Reversible severe lower limb pain during a dipyridamole sestamibi myocardial perfusion study: a case report.

A 68-year-old woman reported acute severe pain in both lower limbs during a dipyridamole sestamibi myocardial perfusion scan. The pain was rapidly relieved by the administration of intravenous aminophylline. A review of the literature on the adverse effects of dipyridamole did not include this symptom.