Poorly differentiated thyroid cancer lesions often lose the ability to concentrate radioactive [131I]iodine (RAI) and exhibit increased metabolic activity, as evidenced by enhanced glucose uptake. We incorporated [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) scanning into the routine follow-up of a cohort of thyroid cancer patients undergoing annual evaluations. One hundred and twenty-five patients who had previous thyroidectomies were included. They had diagnostic RAI whole body scans, serum thyroglobulin measurements, and additional imaging studies as clinically indicated. During 41 months of follow-up, 14 patients died. Univariate analysis demonstrated that survival was reduced in those with age over 45 yr, distant metastases, PET positivity, high rates of FDG uptake, and high volume of the FDG-avid disease (>125 mL). Survival did not correlate with gender, RAI uptake, initial histology, or grade. Multivariate analysis demonstrated that the single strongest predictor of survival was the volume of FDG-avid disease. The 3-yr survival probability of patients with FDG volumes of 125 mL or less was 0.96 (95% confidence interval, 0.91, 1.0) compared with 0.18 (95% confidence interval, 0.04, 0.85) in patients with FDG volume greater than 125 mL. Only 1 death (of leukemia) occurred in the PET-negative group (n = 66). Of the 10 patients with distant metastases and negative PET scans, all were alive and well. Patients over 45 yr with distant metastases that concentrate FDG are at the highest risk. Once distant metastases are discovered in patients with differentiated thyroid carcinoma, FDG-PET can identify high and low risk subsets. Subjects with a FDG volume greater than 125 mL have significantly reduced short term survival.

Prognostic value of [18F]fluorodeoxyglucose positron emission tomographic scanning in patients with thyroid cancer.

High incidence of false-positive PET scans in patients with aggressive non-Hodgkin's lymphoma treated with rituximab-containing regimens

Although studies have shown that (18)F-FDG PET, when used to assess the response of malignant lymphoma after treatment, has a strong ability to predict relapse, its diagnostic accuracy in clinical practice remains unclear. The aim of this study was to systematically review the diagnostic accuracy of (18)F-FDG PET in detecting residual disease at the completion of first-line therapy of Hodgkin's disease (HD) and aggressive non-Hodgkin's lymphoma (NHL). Methods We searched relevant articles from 1966 to July 2006 using MEDLINE, EMBASE, SCOPUS, Biological Abstracts, bibliographies, review articles, and textbooks without language restriction. One assessor (for non-English-language studies) or 2 assessors (for English-language studies) independently reviewed each article to abstract relevant study characteristics and results. Relevant individual patient data or subgroup data were provided by the investigators if they were unavailable from the publications. We estimated summary receiver operating characteristic curves and confidence regions for summary sensitivity and specificity. Results Nineteen studies consisting of 474 HD and 254 aggressive NHL patients were included. These studies had heterogeneity and suboptimal methodologic quality and reporting. Reported ranges for the sensitivity and specificity of (18)F-FDG PET in predicting disease relapse were 0.50-1.00 and 0.67-1.00, respectively, for HD and 0.33-0.77 and 0.82-1.00, respectively, for NHL. These estimates were similar when conventional imaging tests showed a residual mass. For HD studies, the summary receiver operating characteristic curves were similar irrespective of whether a residual mass was detected by conventional tests. Factors explaining the variability of diagnostic estimates were not identified. Conclusion Although currently available evidence is still limited, (18)F-FDG PET seems to have good diagnostic accuracy for assessing residual HD at the completion of first-line treatment. Clinical data on this use of (18)F-FDG PET for aggressive NHL are more limited. Prospective studies with a more rigorous research design, conduct, and reporting would more reliably reveal the clinical diagnostic accuracy of this imaging modality.

https://jnm.snmjournals.org/content/jnumed/49/1/13.full.pdf

18F-FDG PET for Posttherapy Assessment of Hodgkin's Disease and Aggressive Non-Hodgkin's Lymphoma: A Systematic Review

The role of 99mTc-sestamibi and other conventional radiopharmaceuticals in breast cancer diagnosis

Respective roles of thyroglobulin, radioiodine imaging, and positron emission tomography in the assessment of thyroid cancer.

Summary: Background: The aim of this retrospective study was to evaluate the accuracy of fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG-PET) images, which were interpreted under daily routine conditions, in patients with Hodgkin's disease (HD) or non-Hodgkin lymphoma (NHL) for restaging after chemotherapy and/or radiotherapy. For this purpose, 18F-FDG-PET results were compared with morphological imaging methods and the patients’ clinical background.

Methods: 121 PET images of 93 lymphoma patients (44 HD, 49 NHL) were investigated after chemotherapy/radiotherapy. For PET imaging, 160–200 MBq 18F-FDG was administered intravenously, followed by an infusion of 20 mg Furosemid in 250 mL saline. Whole-body 18F-FDG-PET images were obtained using a partial-ring PET scanner without attenuation correction. The morphological imaging consisted in computed tomography and ultrasound (CT/US) in all patients, additional MRI in some patients, and iliac crest biopsy in cases of suspicious bone marrow involvement. The standard of reference was composed of biopsy data, clinical status at the time of investigation, and follow-up of at least 12 months. The PET images were evaluated for their sensitivity, specificity and accuracy based on written reports, which were compiled from other imaging data and the clinical history of the patients.

Results: Sensitivity, specificity, and accuracy of 18F-FDG-PET was 91 %, 81 %, and 85 %; of CT/US, 88 %, 35 %, 56 %, respectively. Major sources of error in 18F-FDG-PET were due to asymmetric muscular hypermetabolism and inflammatory lesions misinterpreted as persistent viable lymphoma tissue. Furthermore, secondary malignancies other than lymphomas were another reason for misinterpretations of 18F-FDG-PET studies.

Conclusions:18F-FDG-PET showed a comparable sensitivity but a higher specificity and accuracy compared with CT/US. To achieve a high accuracy in 18F-FDG-PET, the nuclear medicine specialist needs imaging and clinical data as background information, which can only be acquired through close co-operation with the referring clinicians. Pharmacological muscular relaxation in the course of 18F-FDG-PET imaging may be advisable, as nonspecific muscular hypermetabolism was one of the problems at the image readings and a source of incorrect 18F-FDG-PET interpretations.

Accuracy of whole-body 18F-FDP-PET for restaging malignant lymphoma.

Breast cancer, the most common malignancy in women, still poses a challenge to diagnostic procedures and therapy Despite low specificity routine mammography is the method of choice to screen women for breast cancer In the last years other additional diagnostic procedures such as high frequency ultrasonography (US) and especially magnetic resonance imaging (MRI) have improved breast cancer diagnosis However, all these imaging methods are lacking in specificity which makes biopsy or surgery necessary The purpose of our study was to evaluate prospectively the sensitivity, specificity, PPV and NPV of scintimammography with a new cationic complex Tc-99m tetrofosmin in patients with suspicious mammographic lesions One hundred and thirty seven patients in whom mammography and/or high resolution ultrasonography (10 MHz) revealed suspicious breast lesions were studied with Tc-99m tetrofosmin scintimammography In 84 of them biopsy and/or surgery was performed for histological evaluation After intravenous injection of 555 MBq Tc-99m tetrofosmin planar images in anterior and lateral projections (5 minpi) and SPECT imaging including 3-D-reconstruction (20 minpi) were performed Scintimammography was evaluated as negative, equivocal (+), probably (+2) or definitely (+3) positive Planar scintimammography with Tc-99m tetrofosmin was negative in 46 patients (43 true negative-fn; 3 false negative-fn) and positive in 38 patients (27 true positive-tp; 11 false positive-tp) Using SPECT imaging Tc-99m scintimammography was negative in 43 cases (41 tn; 2fn) and positive in 41 cases (28 tp; 13 tp) Sensitivity of Tc-99m tetrofosmin scintimammography in this prospective study was 90%, specificity 80%, PPV 71% and NPV 93% for planar imaging and 93%, 76%, 68% and 95% for SPECT, respectively Scintimammographic results in patients with suspicious breast lesion show, that Tc-99m tetrofosmin accumulates in breast cancer as well as in some fibroadenoma with high cellularity However, the high NPV of 93 and 95% respectively excludes breast cancer in suspicious mammographic lesions to a very high degree and therefore reduces the need of biopsy and/or surgery in most of these patients

Scintimammography using Tc-99m tetrofosmin.

In the follow up of differentiated thyroid carcinoma (DTC) several scintigraphic methods are used in addition to the serum thyroglobulin and ultrasonography of the neck. Iodine-131 whole body scintigraphy (WBS), which is performed since many years, is able to detect iodine positive recurrence, lymph node metastases and distant metastases in a very specific way. However, the problem of I-131 WBS is the fact that only 67% of metastases from DTC accumulate iodine. Therefore non specific radionuclides like TI-201 or tracers such as Tc-99m Sestamibi or Tc-99m Tetrofosmin and new metabolic tracers like F-18 FDG were introduced in the diagnostic work up to detect iodine negative metastases as well. This study describes the comparison of different tracers in 35 patients with elevated thyroglobulin and suspicion of metastatic disease or already known metastases from DTC.

Comparison of different tracers in the follow up of differentiated thyroid carcinoma.

FDG PET in the Follow-up of Differentiated Thyroid Cancer. Comparison with Tc-99m Tetrofosmin and I-131 Whole Body Scintigraphy.

Especially ectopic adenomas may be problematic in intraoperative localization despite preoperative imaging resulting in a longer operating time and more extensive surgical preparation. The aim of our study was to evaluate the possibility of intraoperative scintimetric detection of parathyroid adenomas with cationic, Tc-99m labelled tracers for its usefulness in ectopic adenomas. 12 women with biochemically confirmed hyperparathyroidism were included in our study. After injection of 370 MBq Tc-99m Tetrofosmin respectively Sestamibi, preoperative scintigraphy (double phase study and SPECT) was performed and T/NT ratios were evaluated for early, delayed and SPECT images. Surgery was performed using a hand-held gamma probe after preoperative injection of 555-925 MBq Tc-99m Tetrofosmin or Sestamibi. Count rates (cts/10 sec) were measured and used for calculating in situ- and ex situ-T/NT ratios. In 9 out of 12 patients, adenoma could be detected on static images. Three cases could only be detected with SPECT. 11 of 12 parathyroid adenomas could be confirmed intraoperatively. Intraoperative localization of parathyroid adenoma with Tc-99m-labelled cationic complexes and a gamma probe is possible and may be useful in case of ectopic adenoma by influencing surgical approach and operating time.

[Use of a gamma probe for intraoperative localization of parathyroid adenomas with Tc-99m-tetrofosmin and Tc-99m-sestamibi].

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