Improved sentinel node identification by SPECT/CT in overweight patients with breast cancer.

UNLABELLED: Overweight has been reported as a cause for the nonvisualization of sentinel nodes (SNs) on preoperative planar lymphoscintigraphy in patients with breast cancer. The purpose of this study was to assess whether SPECT/CT may improve SN identification in overweight patients. METHODS: Lymphoscintigraphy was performed in 220 consecutive patients with breast cancer. Body mass index (BMI) was calculated for each. A total of 122 patients were overweight or obese (BMI, > or = 25). Planar images and SPECT/CT images were interpreted separately, and SN identification on each of the modalities was related to BMI and to findings at surgery. RESULTS: Planar imaging identified SNs in 171 patients (78%) with a BMI (mean +/- SD) of 25.2 +/- 4 kg/m2 and failed to do so in 49 patients (22%) with a BMI of 28 +/- 8 kg/m2. In 29 of the latter patients (59%), SNs were identified on SPECT/CT. SPECT/CT detected "hot" nodes in 200 patients (91%) and failed to do so in 20 patients with a BMI of 29.2 +/- 6.6 kg/m2. For the 122 overweight or obese patients, planar assessment failed to identify SNs in 34 patients (28%) and SPECT/CT failed to do so in 13 patients (11%) (P < 0.001). For 116 patients, surgery took place in our hospital (Tel-Aviv Sourasky Medical Center). An intraoperative blue dye technique failed to detect SNs in 48 patients (41%) with a BMI of 28.2 +/- 7 kg/m2. SPECT/CT localized hot nodes in 36 (75%) of the latter patients, and planar imaging did so in 22 (46%) of those patients. Of 19 patients for whom scintigraphy failed, 6 (32%) had nodal metastatic involvement. CONCLUSION: The addition of SPECT/CT to lymphoscintigraphy improved SN identification in overweight patients with breast cancer. Moreover, SPECT/CT accurately identified SNs in 75% of patients for whom the identification of SNs by the intraoperative blue dye technique failed.

SPECT/multislice low-dose CT: a clinically relevant constituent in the imaging algorithm of nononcologic patients referred for bone scintigraphy.

UNLABELLED: The purpose of this prospective study was to assess the role of SPECT/multislice low-dose (Msl) CT as a constituent in the imaging algorithm of nononcologic patients referred for 99mTc-methylene diphosphonate bone scintigraphy (BS). METHODS: SPECT/CT was performed using a novel hybrid system, which incorporates a gamma-camera and a multislice low-dose CT, on 76 consecutive nononcologic patients with nonspecific scintigraphic findings, which required further correlation with morphologic data. RESULTS: SPECT/MslCT was of added clinical value in 89% of the patients. Characterizing scintigraphic lesions by their morphologic appearance, SPECT/MslCT reached a final diagnosis in 49 of 85 (58%) nonspecific scintigraphic bone lesions found in 59% (45/76) of patients, obviating the need to perform additional imaging. In another 30% of patients (23/76), SPECT/MslCT data optimized the patients' imaging algorithm as the performance of a full-dose CT, MRI, or labeled-leukocyte scintigraphy as the next imaging was based on its findings combined with the patient's clinical presentation. CONCLUSION: SPECT/MslCT is a clinically relevant constituent in the imaging algorithm of nononcologic patients referred for BS.

Back pain in adolescents: assessment with integrated 18F-fluoride positron-emission tomography-computed tomography.

The aim of the present study was to assess the ability of a novel bone imaging technique to diagnose accurately the cause for back pain as an isolated and presenting complaint in adolescents. An integrated 18F-fluoride positron-emission tomography-computed tomography (PET-CT) study was performed at the same setting without changing the patients' position, followed by generation of fused images of functional and anatomical data. Fifteen subjects were included in the study. The interpretation of PET-CT fused images was based on increased 18F-fluoride uptake and the corresponding CT-located abnormality. Ten patients had positive findings that included 4 cases of spondylolysis (3 of them active), 3 frank fractures (2 of the transverse process and 1 of the facet), 2 osteoid osteomas, 1 osteitis pubis, 1 sacroiliitis, and 2 herniated disks. Three patients presented 2 coexisting pathologies. Treatment was tailored based on final diagnosis. In 5 patients, in whom no abnormality was identified, the back pain resolved spontaneously. The 18F-fluoride PET-CT can detect spinal lesions with high diagnostic accuracy in adolescents with back pain. Considering the associated costs and radiation exposure, it should be used at present only in cases of long-standing and disabling back pain in which other imaging modalities were inconclusive.

The presentation of malignant tumours and pre-malignant lesions incidentally found on PET-CT.

PURPOSE: The purpose of the study was to determine the general and organ-specific presentation of incidental primary tumours on PET-CT. METHODS: PET-CT reports of 2,360 consecutive patients were reviewed and revealed 156 lesions suspicious for a new unexpected malignancy, in 151 patients. One hundred and twenty of these lesions, in 115 patients, were further assessed, by biopsy (n=84 patients) or by clinical and imaging follow-up (n=31 patients) for a mean of 17+/-4 months (range 12-25 months). RESULTS: Forty-four unexpected malignancies were found in 41 of the study patients (1.7%). Twenty-seven of the 44 incidental tumours were identified on the basis of their location, which was uncommon for metastasis of the known malignancy. Eight were detected as a result of either the difference in FDG avidity of the known malignancy and the incidental lesion or the presence of an incidental non-FDG-avid mass on the CT part of the study. Four tumours were synchronous carcinomas in patients with known colorectal malignancy, three were identified by virtue of the discordant response to treatment compared with the known primary tumour and two were detected as new sites of disease after a prolonged disease-free period. There was organ variability in the positive predictive values (PPV) of PET-CT findings for incidental primary malignancy or pre-malignant lesions: 62% for colonic lesions, 54% for lung lesions and 24% for thyroid lesions. CONCLUSION: Incidental primary tumours may be identified on PET-CT based on their location, FDG avidity, response to therapy and time of appearance. The PET and CT parts of the study appear to complement each other and assist in identification of these incidental tumours.

The detection of bone metastases in patients with high-risk prostate cancer: 99mTc-MDP Planar bone scintigraphy, single- and multi-field-of-view SPECT, 18F-fluoride PET, and 18F-fluoride PET/CT.

UNLABELLED: The aim of this study was to compare the detection of bone metastases by 99mTc-methylene diphosphonate (99mTc-MDP) planar bone scintigraphy (BS), SPECT, 18F-Fluoride PET, and 18F-Fluoride PET/CT in patients with high-risk prostate cancer. METHODS: In a prospective study, BS and 18F-Fluoride PET/CT were performed on the same day in 44 patients with high-risk prostate cancer. In 20 of the latter patients planar BS was followed by single field-of-view (FOV) SPECT and in 24 patients by multi-FOV SPECT of the axial skeleton. Lesions were interpreted separately on each of the 4 modalities as normal, benign, equivocal, or malignant. RESULTS: In patient-based analysis, 23 patients had skeletal metastatic spread (52%) and 21 did not. Categorizing equivocal and malignant interpretation as suggestive for malignancy, the sensitivity, specificity, positive predictive value, and negative predictive value of planar BS were 70%, 57%, 64%, and 55%, respectively, of multi-FOV SPECT were 92%, 82%, 86%, and 90%, of (18)F-Fluoride PET were 100%, 62%, 74%, and 100%, and of 18F-Fluoride PET/CT were 100% for all parameters. Using the McNemar test, 18F-Fluoride PET/CT was statistically more sensitive and more specific than planar or SPECT BS (P < 0.05) and more specific than 18F-Fluoride PET (P < 0.001). SPECT was statistically more sensitive and more specific than planar BS (P < 0.05) but was less sensitive than 18F-Fluoride PET (P < 0.05). In lesion-based analysis, 156 lesions with increased uptake of 18F-Fluoride were assessed. Based on the corresponding appearance on CT, lesions were categorized by PET/CT as benign (n = 99), osteoblastic metastasis (n = 46), or equivocal when CT was normal (n = 11). Of the 156 18F-Fluoride lesions, 81 lesions (52%), including 34 metastases, were overlooked with normal appearance on planar BS. SPECT identified 62% of the lesions overlooked by planar BS. 18F-Fluoride PET/CT was more sensitive and more specific than BS (P < 0.001) and more specific than PET alone (P < 0.001). CONCLUSION: 18F-Fluoride PET/CT is a highly sensitive and specific modality for detection of bone metastases in patients with high-risk prostate cancer. It is more specific than 18F-Fluoride PET alone and more sensitive and specific than planar and SPECT BS. Detection of bone metastases is improved by SPECT compared with planar BS and by 18F-Fluoride PET compared with SPECT. This added value of 18F-Fluoride PET/CT may beneficially impact the clinical management of patients with high-risk prostate cancer.

18F-FDG PET/CT in the evaluation of adrenal masses.

UNLABELLED: Our purpose was to evaluate the performance of (18)F-FDG PET/CT, using data from both the PET and the unenhanced CT portions of the study, in characterizing adrenal masses in oncology patients. METHODS: One hundred seventy-five adrenal masses in 150 patients referred for (18)F-FDG PET/CT were assessed. Final diagnosis was based on histology (n = 6), imaging follow-up (n = 118) of 6-29 mo (mean, 14 mo), or morphologic imaging criteria (n = 51). Each adrenal mass was characterized by its size; its attenuation on CT, expressed by Hounsfield units (HU); and the intensity of (18)F-FDG uptake, expressed as standardized uptake value (SUV). Receiver operating characteristic curves were drawn to determine the optimal cutoff values of HU and SUV that would best discriminate between benign and malignant masses. RESULTS: When malignant lesions were compared with adenomas, PET data alone using an SUV cutoff of 3.1 yielded a sensitivity, specificity, positive predictive value, and negative predictive value of 98.5%, 92%, 89.3%, 98.9%, respectively. For combined PET/CT data, the sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 98%, 97%, 100%, respectively. Specificity was significantly higher for PET/CT (P < 0.01). Fifty-one of the 175 masses were 1.5 cm or less in diameter. When a cutoff SUV of 3.1 was used for this group, (18)F-FDG PET/CT correctly classified all lesions. CONCLUSION: (18)F-FDG PET/CT improves the performance of (18)F-FDG PET alone in discriminating benign from malignant adrenal lesions in oncology patients.

Differentiation between malignant and benign pleural effusion in patients with extra-pleural primary malignancies: assessment with positron emission tomography-computed tomography.

OBJECTIVES: We sought to define an accurate diagnostic approach for differentiating benign from malignant pleural effusion on positron emission tomography-computed tomography (PET-CT). MATERIAL AND METHODS: PET-CT studies of 31 patients with primary extrapleural malignancy and pleural effusion were reviewed retrospectively. CT parameters assessed were size and density (Hounsfield units, or HU) of the effusion and density (HU) and morphology of any solid pleural abnormality. Interpretation of PET data included review of the attenuation-corrected and nonattenuation-corrected images. RESULTS: PET-CT parameters that were found to be significant in identifying malignant pleural effusion included focal increased uptake of 18-fluorodeoxyglucose in the pleura (P<0.0001) and the presence of solid pleural abnormalities on CT (P<0.002): the sensitivity was 86% and 71%, respectively, and the specificity was 90% for each of the 2 parameters. A PET-CT pattern composed of pleural uptake and increased effusion activity on nonattenuation-corrected images was associated with sensitivity of 95%, specificity of 80%, positive predictive value of 91%, negative predictive value of 89%, and accuracy of 90%. CONCLUSIONS: On PET-CT, the presence of concomitant pleural abnormalities is the most accurate criterion in determining the malignant nature of pleural effusion.

Solid splenic masses: evaluation with 18F-FDG PET/CT.

UNLABELLED: Our objective was to assess the role of (18)F-FDG PET/CT in the evaluation of solid splenic masses in patients with a known malignancy and in incidentally found lesions in patients without known malignancy. METHODS: Two groups of patients were assessed: (a) 68 patients with known malignancy and a focal lesion on PET or a solid mass on CT portions of the PET/CT study; and (b) 20 patients with solid splenic masses on conventional imaging without known malignancy. The standard of reference was histology (n = 16) or imaging and clinical follow-up (n = 72). The lesion size, the presence of a single versus multiple splenic lesions, and the intensity of (18)F-FDG uptake expressed as a standardized uptake value (SUV) were recorded. The ratio of the SUV in the splenic lesion to the background normal splenic uptake was also calculated. These parameters were compared between benign and malignant lesions within each of the 2 groups of patients and between the 2 groups. RESULTS: The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of (18)F-FDG PET/CT in differentiating benign from malignant solid splenic lesions in patients with and without malignant disease were 100%, 100%, 100%, and 100% versus 100%, 83%, 80%, and 100%, respectively. In patients with known malignant disease, an SUV threshold of 2.3 correctly differentiated benign from malignant lesions with the sensitivity, specificity, PPV, and NPV of 100%, 100%, 100%, and 100%, respectively. In patients without known malignant disease, false-positive results were due to granulomatous diseases (n = 2). CONCLUSION: (18)F-FDG PET can reliably discriminate between benign and malignant solid splenic masses in patients with known (18)F-FDG-avid malignancy. It also appears to have a high NPV in patients with solid splenic masses, without known malignant disease. (18)F-FDG-avid splenic masses in patients without a known malignancy should be further evaluated as, in our series, 80% of them were malignant.

Assessment of malignant skeletal disease: initial experience with 18F-fluoride PET/CT and comparison between 18F-fluoride PET and 18F-fluoride PET/CT.

UNLABELLED: 18F-fluoride PET/CT was performed on 44 oncologic patients to evaluate its diagnostic accuracy in assessing malignant osseous involvement and in differentiating malignant from benign bone lesions. METHODS: (18)F-fluoride PET and (18)F-fluoride PET/CT were interpreted separately. Lesions showing increased (18)F-fluoride uptake were categorized as malignant, benign, or inconclusive. The final diagnosis of lesions was based on histopathology, correlation with contemporaneous diagnostic CT or MRI, or clinical follow-up of at least 6 mo (mean, 10 +/- 3 mo). RESULTS: Increased (18)F-fluoride uptake was detected at 212 sites, including 111 malignant lesions, 89 benign lesions, and 12 lesions for which the final diagnosis could not be determined. In a lesion-based analysis, the sensitivity of PET alone in differentiating benign from malignant bone lesions was 72% when inconclusive lesions were considered false negative and 90% when inconclusive lesions were considered true positive. On PET/CT, 94 of 111 (85%) metastases presented as sites of increased uptake with corresponding lytic or sclerotic changes, and 16 of the 17 remaining metastases showed normal-appearing bone on CT, for an overall sensitivity of 99% for tumor detection. For only 1 metastasis was PET/CT misleading, suggesting the false diagnosis of a benign lesion. The specificity of PET/CT was significantly higher than that of PET alone (97% vs. 72%, P < 0.001). PET/CT identified benign abnormalities at the location exactly corresponding to the scintigraphic increased uptake for 85 of 89 (96%) benign lesions. In a patient-based analysis, the sensitivity of PET and PET/CT was 88% and 100%, respectively (P < 0.05) and the specificity was 56% and 88%, respectively (not statistically significant). Among the 12 patients referred for (18)F-fluoride assessment because of bone pain despite negative findings on (99m)Tc-methylene diphosphonate bone scintigraphy, (18)F-fluoride PET/CT suggested malignant bone involvement in all 4 patients with proven skeletal metastases, a potential benign cause in 4 of 7 patients who had no evidence of metastatic disease, and a soft-tissue tumor mass invading a sacral foramen in 1 patient. CONCLUSION: The results indicate that (18)F-fluoride PET/CT is both sensitive and specific for the detection of lytic and sclerotic malignant lesions. It accurately differentiated malignant from benign bone lesions and possibly assisted in identifying a potential cause for bone pain in oncologic patients. For most lesions, the anatomic data provided by the low-dose CT of the PET/CT study obviates the performance of full-dose diagnostic CT for correlation purposes.

Normal and abnormal 18F-FDG endometrial and ovarian uptake in pre- and postmenopausal patients: assessment by PET/CT.

UNLABELLED: The purpose of the study was to assess physiologic endometrial (18)F-FDG uptake during the 4 phases of the menstrual cycle and to differentiate between physiologic and malignant endometrial uptake. METHODS: Endometrial (18)F-FDG uptake, expressed as standardized uptake value (SUV), was measured on PET/CT images of 285 consecutive female patients, of whom 246 (112 premenopausal and 134 postmenopausal) had no known gynecologic malignancy and 39 (14 premenopausal and 25 postmenopausal) had cervical, endometrial, or ovarian cancer. RESULTS: Two peaks of increased endometrial (18)F-FDG uptake were identified during the 4-phase cycle. The mean SUVs were 5 +/- 3.2 and 3.7 +/- 0.9 in menstruating and ovulating patients, respectively, and 2.6 +/- 1.1 and 2.5 +/- 1.1 in patients in the proliferative and secretory phases, respectively. The mean endometrial SUV in postmenopausal patients not receiving hormonal therapy was 1.7 +/- 0.5. Oligomenorrhea and benign endometrial abnormalities were associated with increased (18)F-FDG uptake. Neither contraceptives nor hormonal therapy was associated with a significant increase in endometrial uptake. In addition to the increased tumor uptake measured in patients with cervical cancer (14.9 +/- 7.3 in postmenopausal patients and 12.2 +/- 6.6 in premenopausal patients), increased uptake was also found in the adjacent endometrium, although it appeared normal on CT (4.8 +/- 2 in premenopausal patients and 4.7 +/- 2.8 in postmenopausal patients). Increased ovarian (18)F-FDG uptake was detected in 7 patients with ovarian cancer (9.1 +/- 4) and in 21 premenopausal patients without known ovarian malignancy (5.7 +/- 1.5, P < 0.01), of whom 15 were at mid cycle and 3 reported oligomenorrhea. An ovarian SUV of 7.9 separated benign from malignant uptake with a sensitivity of 57% and a specificity of 95%. CONCLUSION: In premenopausal patients, normal endometrial uptake of (18)F-FDG changes cyclically, increasing during the ovulatory and menstrual phases. Increased uptake in the endometrium adjacent to a cervical tumor does not necessarily reflect endometrial tumor invasion. Increased ovarian uptake in postmenopausal patients is associated with malignancy, whereas increased ovarian uptake may be functional in premenopausal patients.

Malignant involvement of the spine: assessment by 18F-FDG PET/CT.

UNLABELLED: The purpose of the study was to assess the role of (18)F-FDG PET/CT in the assessment of secondary malignant involvement of the spinal column. METHODS: In 51 patients, 242 lesions at the spinal region detected on (18)F-FDG PET/CT were interpreted separately on PET, CT, and fused PET/CT images, including differentiation between benign and malignant lesions and the level in the vertebral column. CT evaluation also included the type of bony lesion (osteolytic, osteoblastic, or mixed) and accompanying soft-tissue abnormalities; for example, epidural masses and tumor involvement of the neural foramina. RESULTS: Of the 242 lesions detected on PET/CT, PET alone identified 220 lesions and CT alone identified 159; 217 (90%) were malignant and 25 benign. (18)F-FDG PET alone detected significantly more malignant lesions than did CT alone (96% vs. 68%, respectively, P < 0.001). The specificity was 56% for both PET alone and CT alone. PET alone was incorrect in determining the level of abnormality within the vertebral column in 33 (15%) lesions and in determining the part of the vertebra involved in 40 (18%) lesions. In 17 (33%) patients, either epidural extension of tumor (n = 7 lesions), neural foramen involvement of tumor (n = 7 lesions), or a combination of both (n = 11 lesions) was detected. On a patient-based analysis, the sensitivity of PET and of PET/CT for the detection of spinal metastasis was 98% and 74%, respectively (P < 0.01). CONCLUSION: (18)F-FDG PET/CT has better specificity for detection of malignant involvement of the spine than does (18)F-FDG PET. It allows for precise localization of lesions and identifies accompanying soft-tissue involvement, which is of potential neurologic significance.