Diagnostic value of diffusion-weighted magnetic resonance imaging (DWI) compared to FDG PET/CT for whole-body breast cancer staging.

PURPOSE: The aim of the study was to prospectively compare the diagnostic value of whole-body diffusion-weighted imaging (DWI) and FDG PET/CT for breast cancer (BC) staging. METHODS: Twenty BC patients underwent whole-body FDG PET/CT and 1.5-T DWI. Lesions with qualitatively elevated signal intensity on DW images (b = 800 s/mm(2)) were rated as suspicious for tumour and mapped to individual lesions and different compartments (overall 552 lesions). The apparent diffusion coefficient (ADC) value was determined for quantitative evaluation. Histopathology, MRI findings, bone scan findings, concordant findings between FDG PET/CT and DWI, CT follow-up scans and plausibility served as the standards of reference defining malignancy. RESULTS: According to the standards of reference, breasts harboured malignancy in 11, regional lymph nodes in 4, M1 lymph nodes in 3, bone in 7, lung in 2, liver in 3 and other tissues in 3 patients. On a compartment basis, the sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) for the detection of malignancies were 94, 99, 98, 97 and 98% for FDG PET/CT and 91, 72, 76, 50 and 96% for DWI, respectively. Of the lesions seen on DWI only, 348 (82%) turned out to be false-positive compared to 23 (11%) on FDG PET/CT. The average lesion ADC was 820 +/- 300 with true-positive lesions having 929 +/- 252 vs 713 +/- 305 in false-positive lesions (p < 0.0001). CONCLUSION: Based on these initial data DWI seems to be a sensitive but unspecific modality for the detection of locoregional or metastatic BC disease. There was no possibility to quantitatively distinguish lesions using ADC. DWI alone may not be recommended as a whole-body staging alternative to FDG PET(/CT). Further studies are necessary addressing the question of whether full-body MRI including DWI may become an alternative to FDG PET/CT for whole-body breast cancer staging.

Diagnostic value of full-dose FDG PET/CT for axillary lymph node staging in breast cancer patients.

PURPOSE: The aims of this study were (1) to evaluate FDG PET/CT and CT for the detection of axillary lymph node metastases in breast cancer (BC) patients and (2) to evaluate FDG PET/CT as a pre-test for the triage to sentinel lymph node biopsy (SLNB) versus axillary lymph node dissection (ALND). METHODS: The sensitivity, specificity, positive and negative predictive value (PPV, NPV), and accuracy of FDG PET/CT and CT for axillary lymph node metastases were determined in 61 patients (gold standard: histopathology). According to the equation "NPV = specificity (1-prevalence) / [specificity (1-prevalence) + (1-sensitivity) prevalence]" FDG PET/CT was evaluated as a triage tool for SLNB versus ALND. RESULTS: The sensitivity, specificity, PPV, NPV and accuracy of FDG PET/CT was 58, 92, 82, 77 and 79% and of CT 46, 89, 72, 71 and 72%, respectively. Patients with an up to approximately 60% risk for axillary lymph node metastases appear to be candidates for SLNB provided that the axilla is unremarkable on FDG PET/CT. CONCLUSION: FDG PET/CT cannot replace invasive approaches for axillary staging but may extend the indication for SLNB.

Gastrointestinal 18F-FDG accumulation on PET without a corresponding CT abnormality is not an early indicator of cancer development.

Focal gastrointestinal 2-deoxy-2-[(18)F]-fluoro-D: -glucose (FDG) uptake can frequently be found on FDG-PET/CT even in patients without known gastrointestinal malignancy. The aim of this study was to evaluate whether increased gastrointestinal FDG uptake without CT correlate is an early indicator of patients developing gastrointestinal malignancies. A total of 1,006 patients without esophagogastric or anorectal malignancies underwent FDG-PET/CT. The esophagogastric junction, the stomach and the anorectum were evaluated for increased FDG uptake. Patients without elevated uptake were assigned to group A, patients with elevated uptake were allocated to group B. The SUVmax values of both groups were tested for significant differences using the U test. A follow-up of longer than 1 year (mean 853 +/- 414 days) served as gold standard. A total of 460 patients had to be excluded based on insufficient follow-up data. For the remaining 546 patients the mean SUVmax was as follows: (a) esophagogastric junction, group A 3.1 +/- 0.66, group B 4.0 +/- 1.11, p < 0.01; (b) stomach, group A 2.8 +/- 0.77, group B 4.1 +/- 1.33, p < 0.01; (c) rectal ampulla, group A 2.8 +/- 0.83, group B 3.9 +/- 1.49, p < 0.01; (d) anal canal, group A 2.7 +/- 0.55, group B 3.9 +/- 1.59, p < 0.01. Only one patient developed gastric cancer. In the case of an unremarkable CT, elevated esophagogastric or anorectal FDG uptake does not predict cancer development and does not have to be investigated further.

SPECT/CT with 99mTc-MAA in radioembolization with 90Y microspheres in patients with hepatocellular cancer.

UNLABELLED: Radioembolization with (90)Y microspheres is a novel treatment for hepatic tumors. Generally, hepatic arteriography and (99m)Tc-macroaggregated albumin (MAA) scanning are performed before selective internal radiation therapy to detect extrahepatic shunting to the lung or the gastrointestinal tract. Whereas previous studies have used only planar or SPECT scans, the present study used (99m)Tc-MAA SPECT/CT scintigraphy (SPECT with integrated low-dose CT) to evaluate whether SPECT/CT and additional diagnostic contrast-enhanced CT before radioembolization with (90)Y microspheres are superior to SPECT or planar imaging alone for detection of gastrointestinal shunting. METHODS: In a prospective study, we enrolled 58 patients (mean age, 66 y; SD, 12 y; 10 women and 48 men) with hepatocellular carcinoma who underwent hepatic arteriography and scintigraphy with (99m)Tc-MAA using planar imaging, SPECT, and SPECT with integrated low-dose CT of the upper abdomen (acquired with a hybrid SPECT/CT camera). The ability of the different imaging modalities to detect extrahepatic MAA shunting was compared. Patient follow-up of a mean of 180 d served as the standard of reference. RESULTS: Gastrointestinal shunting was revealed by planar imaging in 4, by SPECT in 9, and by SPECT/CT in 16 of the 68 examinations. For planar imaging, the sensitivity for detection of gastrointestinal shunting was 25%, the specificity 87%, and the accuracy 72%. For SPECT without CT, the sensitivity was 56%, the specificity 87%, and the accuracy 79%. SPECT with CT fusion had a sensitivity of 100%, a specificity of 94%, and an accuracy of 96%. In 3 patients, MAA deposits in the portal vein could accurately be attributed to tumor thrombus only with additional information from contrast-enhanced CT. The follow-up did not show any gastrointestinal complications. CONCLUSION: SPECT with integrated low-dose CT using (99m)Tc-MAA is beneficial in radioembolization with (90)Y microspheres because it increases the sensitivity and specificity of (99m)Tc-MAA SPECT when detecting extrahepatic arterial shunting. The overall low risk of gastrointestinal complications in radioembolization may therefore be further reduced by SPECT/CT.

Incidental head and neck (18)F-FDG uptake on PET/CT without corresponding morphological lesion: early predictor of cancer development?

PURPOSE: To retrospectively determine whether increased/asymmetric FDG uptake on PET without a correlating morphological lesion on fully diagnostic CT indicates the development of a head and neck malignancy. METHODS: In 590 patients (mean age 55.4 +/- 13.3 years) without a head and neck malignancy/inflammation FDG uptake was measured at (a) Waldeyer's ring, (b) the oral floor, (c) the larynx, and (d) the thyroid gland, and rated as absent (group A), present (group B), symmetric (group B1) or asymmetric (group B2). Differences between groups A and B and between B1 and B2 were tested for significance with the U-test (p < 0.05). An average follow-up of about 2.5 years (mean 29.5 +/- 13.9 months) served as the reference period to determine whether patients developed a head and neck malignancy. RESULTS: Of the 590 patients, 235 (40%) showed no evidence of enhanced FDG uptake in any investigated site, and 355 (60%) showed qualitatively elevated FDG uptake in at least one site. FDG uptake values (SUV(max), mean+/-SD) for Waldeyer's ring were 3.0 +/- 0.89 in group A (n = 326), 4.5 +/- 2.18 in group B (n = 264; p < 0.01), 5.4 +/- 3.35 in group B1 (n = 177), and 4.1 +/- 1.7 in group B2 (n = 87; p < 0.01). Values for the oral floor were 2.8 +/- 0.74 in group A (n = 362), 4.7 +/- 2.55 in group B (n = 228; p < 0.01), 4.4 +/- 3.39 in group B1 (n = 130), and 5.1 +/- 2.69 in group B2 (n = 98, p = 0.01). Values for the larynx were 2.8 +/- 0.76 in group A (n = 353), 4.2 +/- 2.05 in group B (n = 237; p < 0.01), 4.0 +/- 2.02 in group B1 (n = 165), and 4.6 +/- 2.8 in group B2 (n = 72; p = 0.027). Values for the thyroid were 2.4 +/- 0.63 in group A (n = 404), 3.0 +/- 1.01 in group B (n = 186; p < 0.01), 2.6 +/- 0.39 in group B1 (n = 130), and 4.0 +/- 1.24 in group B2 (n = 56; p < 0.01). One patient developed a palatine tonsil carcinoma (group B1, SUV(max) 3.2), and one patient developed an oral floor carcinoma (group B1, SUV(max) 3.7). CONCLUSION: Elevated/asymmetric head and neck FDG accumulation without a correlating morphological lesion can frequently be found and does not predict cancer development. In populations in which goitre is endemic, FDG uptake by the thyroid is common and not associated with thyroid cancer.