Alexander Becherer

2-18fluoro-deoxy-D-glucose Positron Emission Tomography Is a Reliable Predictor for Viable Tumor in Postchemotherapy Seminoma: An Update of the Prospective Multicentric SEMPET Trial

PURPOSE To define the clinical value of 2-18fluoro-deoxy-D-glucose positron emission tomography (FDG PET) as a predictor for viable residual tumor in postchemotherapy seminoma residuals in a prospective multicentric trial. PATIENTS AND METHODS FDG PET studies in patients with metastatic pure seminoma who had radiographically defined postchemotherapy residual masses were correlated with either the histology of the resected lesion or the clinical outcome documented by computer tomography (CT), tumor markers, and/or physical examination during follow-up. The size of the residual lesions on CT, either >3 cm or < or =3 cm, was correlated with the presence or absence of viable residual tumor. RESULTS Fifty-six FDG PET scans of 51 patients were assessable. All 19 cases with residual lesions >3 cm and 35 (95%) of 37 with residual lesions < or =3 cm were correctly predicted by FDG PET. The specificity, sensitivity, positive predictive value, and negative predictive value of FDG PET were 100% (95% CI, 92% to 100%), 80% (95% CI, 44% to 95%), 100%, and 96%, respectively, versus 74% (95% CI, 58% to 85%), 70% (95% CI, 34% to 90%), 37%, and 92%, respectively, for CT discrimination of the residual tumor by size (>3 cm/< or =3 cm). CONCLUSION This investigation confirms that FDG PET is the best predictor of viable residual tumor in postchemotherapy seminoma residuals and should be used as a standard tool for clinical decision making in this patient group.

Predictive Impact of 2-18Fluoro-2-Deoxy-d-Glucose Positron Emission Tomography for Residual Postchemotherapy Masses in Patients With Bulky Seminoma

PURPOSE To establish the predictive potential of 2-18fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) for detecting viable tumor tissue in residual postchemotherapy masses of seminoma patients. PATIENTS AND METHODS In this prospective multicenter trial, results of FDG PET studies in seminoma patients with postchemotherapy masses > or = 1 cm were correlated with either the histology of the resected lesion or the clinical outcome on follow-up without resection. Negative PET scans of residual lesions that were devoid of viable tumor tissue on resection or disappeared, shrunk, or remained stable in size for at least 2 years were rated as true-negative (TN). Positive scans without histologic or clinical evidence of tumor tissue were classified as false-positive. In patients with histologically positive or progressive lesions, positive PET scans were defined as true-positive (TP) and negative scans, false-negative (FN). RESULTS Thirty-seven PET scans of 33 patients were assessable at a median follow-up time of 23 months (range, 2 to 46 months). Histologic data were available from nine patients who had undergone resection. Twenty-eight patients were followed-up clinically and radiologically. Twenty-eight scans were TN, eight were TP, and one was FN. All 14 residual lesions more than 3 cm and 22 (96%) of the 23 < or = 3 cm were correctly predicted by FDG PET. The specificity (100%; 95% confidence interval [CI], 87.7% to 100%), sensitivity (89%; 95% CI, 51.7% to 99.7%), positive predictive value (100%), and the negative predictive value (97%) of FDG PET were superior to data obtained by assessing residual tumor size (< or = or > 3 cm). CONCLUSION FDG PET is a clinically useful predictor of viable tumor in postchemotherapy residuals of pure seminoma, especially those greater than 3 cm.

18F-Fluorodeoxyglucose Positron Emission Tomography (18F-FDG-PET) for Staging and Follow-Up of Marginal Zone B-Cell Lymphoma

Objective: According to recent reports, nodal marginal zone lymphoma (MZL) appears to be a distinctive lymphoma entity rather than a more advanced stage of extranodal MZL of mucosa-associated lymphoid tissue (MALT). We have therefore retrospectively evaluated all patients diagnosed with nodal or extranodal MZL who have been referred to our unit for imaging using 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET). Patients and Methods: A total of 21 patients with a diagnosis of MZL upon referral for imaging with 18F-FDG-PET were identified. Histological reassessment of biopsy specimens confirmed the diagnosis of extranodal MZL of MALT in 14 patients, while a diagnosis of nodal MZL was verified in 6 patients. Lymphoma cell proliferation was assessed immunohistochemically using a Ki-67 antibody. Whole-body 18F-FDG-PET scans were performed on a GE advanced PET scanner 40 min after intravenous injection of 300–380 MBq 18F-FDG. Results: None of the patients with extranodal MZL showed focal tracer uptake within verified tumor sites. In contrast, 5 of the 6 patients with nodal MZL showed significant FDG uptake within the affected lymph nodes. These results did not simply reflect the different growth fractions of the two lymphoma entities since the proliferation indices of the two groups did not differ significantly. Conclusion:18F-FDG-PET visualizes nodal MZL in a high proportion of patients whereas FDG uptake is undetectable in extranodal MZL. Although limited by the small number of patients, this study suggests that imaging with 18F-FDG-PET might play a potential role in the diagnostic workup of patients with nodal MZL involvement.

11C-Acetate Positron Emission Tomography Imaging and Image Fusion With Computed Tomography and Magnetic Resonance Imaging in Patients With Recurrent Prostate Cancer

PURPOSE To assess the clinical value of computed tomography (CT) and magnetic resonance imaging (MRI) image fusion with 11C-acetate (AC) positron emission tomography (PET) imaging for detection and exact location of clinically occult recurrences. PATIENTS AND METHODS Fifty prostate cancer patients with elevated/increasing serum prostate-specific antigen levels after radical therapy underwent whole-body AC PET. Uptake was initially interpreted as normal, abnormal, or equivocal. In case of abnormal or equivocal uptake, additional conventional imaging techniques, such as CT, MRI, and bone scans, were performed. To precisely define the anatomic location of abnormal uptake and to improve characterization of equivocal lesions, a software-assisted image fusion (CT-PET, MRI-PET) was performed and evaluated as site-by-site analysis of 51 abnormal (n = 37) or equivocal (n = 14) sites of all 50 patients. In 17 patients, additional histopathologic evaluation was available. RESULTS In five (10%), 13 (26%), and 32 (64%) of the 50 patients, AC PET studies demonstrated AC uptake judged as normal, equivocal, and abnormal, respectively. Image fusion changed characterization of equivocal lesions as normal in five (10%) of 51 sites and abnormal in nine (18%) of 51 sites. It precisely defined the anatomic location of abnormal uptake in 37 (73%) of 51 sites. AC PET findings did influence patient management in 14 (28%) of 50 patients. CONCLUSION Retrospective fusion of AC PET and CT/MRI is feasible and seems to be essential for final diagnosis. This is particularly true in patients with AC uptake in the prostate region.

BRCA1‐related breast cancer in Austrian breast and ovarian cancer families: Specific BRCA1 mutations and pathological characteristics

We identified 17 BRCA1mutations in 86 Austrian breast and ovarian cancer families (20%) that were screened for mutations by denaturing high‐performance liquid chromatography (DHPLC) and the protein<0B> <0R>truncation test (PTT). Eleven distinct mutations were detected, 4 of them (962del4, 2795del4, 3135del4 and L3376stop) not previously reported in families of non‐Austrian origin. In addition, 6 rare missense mutations (allele frequency < 1%) with unknown biological effects were identified. Four mutations occurred more than once in the Austrian population: 2795del4 (3 times), Cys61Gly (3 times) 5382insC (2 times) and Q1806stop (2 times). Haplotype analysis of the 4 recurrent mutations suggested a common ancestor for each of these. Thirty‐four breast cancer cases from 17 families with BRCA1 mutations were further analyzed. We observed a low median age of onset (39.5 years). Sixty‐eight percent of all BRCA1 breast cancer cases had negative axillary lymph nodes. This group showed a significant prevalence of a negative estrogen and progesterone receptor status and stage I tumors compared with an age‐related, node‐negative control group. The prevalence of grade III tumors was marginally significant . Survival analysis either with a control group matched for age (within 5 years), grade, histologic subtype and estrogen receptor status, or with an age‐related, node‐negative comparison group, showed no statistical difference. Int. J. Cancer 77:354–360, 1998.

Positron emission tomography imaging of adrenal masses: 18F-fluorodeoxyglucose and the 11β-hydroxylase tracer 11C-metomidate

Purpose11C-metomidate (MTO), a marker of 11β-hydroxylase, has been suggested as a novel positron emission tomography (PET) tracer for adrenocortical imaging. Up to now, experience with this very new tracer is limited. The aims of this study were (1) to evaluate this novel tracer, (2) to point out possible advantages in comparison with 18F-fluorodeoxyglucose (FDG) and (3) to investigate in vivo the expression of 11β-hydroxylase in patients with primary aldosteronism.Methods Sixteen patients with adrenal masses were investigated using both MTO and FDG PET imaging. All patients except one were operated on. Five patients had non-functioning adrenal masses, while 11 had functioning tumours(Cushing’s syndrome, n=4; Conn’s syndrome, n=5; phaeochromocytoma, n=2). Thirteen patients had benign disease, whereas in three cases the adrenal mass was malignant (adrenocortical cancer, n=1; malignant phaeochromocytoma, n=1; adrenal metastasis of renal cancer, n=1).ResultsMTO imaging clearly distinguished cortical from non-cortical adrenal masses (median standardised uptake values of 18.6 and 1.9, respectively, p<0.01). MTO uptake was slightly lower in patients with Cushing’s syndrome than in those with Conn’s syndrome, but the difference did not reach statistical significance. The expression of 11β-hydroxylase was not suppressed in the contralateral gland of patients with Conn’s syndrome, whereas in Cushing’s syndrome this was clearly the case. The single patient with adrenocortical carcinoma had MTO uptake in the lower range.ConclusionMTO could not definitely distinguish between benign and malignant disease. FDG PET, however, identified clearly all three study patients with malignant adrenal lesions. We conclude: (1) MTO is an excellent imaging tool to distinguish adrenocortical and non-cortical lesions; (2) the in vivo expression of 11β-hydroxylase is lower in Cushing’s syndrome than in Conn’s syndrome, and there is no suppression of the contralateral gland in primary aldosteronism; (3) for the purpose of discriminating between benign and malignant lesions, FDG is the tracer of choice.

Comparison and histopathological correlation of three parathyroid imaging methods in a population with a high prevalence of concomitant thyroid diseases

The aim of this prospective study was to evaluate the diagnostic utility of a technetium-99m sestamibi dual-phase protocol enhanced by single-photon emission tomography (SPET) and semiquantitative analysis in comparison to established preoperative staging procedures in patients with primary hyperparathyroidism. Twenty-eight (50%) out of 56 patients had superimposed thyroid disease, and 12 patients had previously undergone neck surgery. Visual and semiquantitative analysis of planar99mTc-sestamibi dual-phase imaging, SPET of the delayed phase, ultrasonography, and thallium-201 chloride-technetium-99m pertechnetate subtraction scintigraphy was further correlated with the histopathological examination of the surgical specimens.99mTc-sestamibi dual-phase imaging achieved the highest sensitivity for side localization and precise localization compared with201Tl-99mTc subtraction scintigraphy and ultrasonography, but the differences reached statistical significance only in comparison to ultrasonography. Semiquantitative analysis did not enhance sensitivity. Adenoma detection by99mTc-sestamibi dual-phase imaging was only correlated to serum calcium levels and osteocalcin, not to cell density or oxyphil cell count (SPET yielded additional information for the exact topographical localization of the parathyroid tumour in 22 (39%) patients with superimposed thyroid disease or previous neck surgery but did not enhance the overall detection rate.

FDG-PET in adrenocortical carcinoma.

Adrenal cortical carcinoma (ACC) is a rare malignant neoplasm with a poor prognosis. Radical surgery of the primary tumor and of local as well as of distant recurrence is the only effective treatment, and requires accurate and early localization of recurrent tumors. In this regard, we prospectively scanned 10 patients with ACC, 8 during follow-up and 2 at primary work-up. In all patients PET scans from the neck to the upper thighs were obtained 45 minutes after injection of 370 MBq [18F]FDG. Reading was done visually, with the investigator blinded to the results of other diagnostic modalities. All known sites of ACC lesions showed markedly increased FDG uptake. In 3 patients, previously unknown lesions were identified by PET in the lung (one lesion), the abdomen (3 lesions), and the skeleton (multiple), respectively. One false positive liver focus was shown by PET aside from the true positive lung metastases in the same patient. The sensitivity/specificity of PET based on different organs was 100/97%, that based on the number of PET-detected lesions (N = 23) was 100/95%. PET altered or influenced the tumor stage in 3/10 patients, modifying the subsequent therapeutic management in 2/10 patients. We conclude that FDG-PET is highly useful in ACC and should be included in the work-up for initial staging as well as for follow-up.

Isotopic renal function studies in severe hypothyroidism and after thyroid hormone replacement therapy.

Aim: To investigate the possible changes in the renal tubular function in severe short-term hypothyroidism using 99mTc-MAG3 renography. Methods: 27 consecutive thyroidectomized patients (7 males and 20 females) aged 19–79 (mean 53) years were included in the present study. 99mTc-MAG3 renography was performed in all patients before and after thyroid hormone replacement therapy. In addition, 51Cr-EDTA clearance and serum creatinine concentrations were determined. Results: The serum creatinine concentrations were significantly increased in hypothyroidism as compared with the concentrations after thyroxine substitution (1.30 ± 0.44 vs. 1.04 ± 0.32 mg/dl, p < 0.05). According to the 51Cr-EDTA clearance, the glomerular filtration rate was significantly lower in hypothyroidism than after treatment (61 ± 18 vs. 75 ± 23 ml/min). In contrast, we did not find any significant change in the renographic parameters for 99mTc-MAG3 before and after treatment (total excreted activity 20 min after administration 51 ± 12 vs. 54 ± 14%; Tmax left:right 4.2 ± 1.77 : 3.91 ± 1.06 min vs. 4.1 ± 1.66 : 4.4 ± 1.96 min). Conclusions: We did not find any influence of thyroid hormones on the outcome of 99m Tc-MAG3 renography. As 99mTc-MAG3 reflects the tubular function, it seems that the renal hemodynamic changes in severe hypothyroidism mainly affect the glomerular function. In general, the glomerular filtration rate reduction seems to be reversible after hormone substitution therapy; however, care has to be taken in patients with renal insufficiency.

Diagnostic imaging in Merkel cell carcinoma: Lessons to learn from 16 cases with correlation of sonography, CT, MRI and PET ☆

OBJECTIVE The authors report imaging findings in a series of 16 patients with MCC, a rare tumour which is often managed primarily by a dermatologist. To our knowledge, no equivalent series of MCC has been described in the nuclear medicine literature. MATERIAL AND METHODS In this IRB-approved retrospective noncomparative case series 16 patients with biopsy-proven Merkel cell carcinoma were included between January 1999 and October 2007. Twenty-nine whole body PET scans (18F-FDG n=24, 18F-FDOPA n=5) in 16 patients were retrospectively reviewed with regard to tracer uptake in six anatomical sites per patient. For 127/144 of FDG-PET evaluated regions and 68/144 of regions depicted by conventional imaging methods, a valid standard of reference could be obtained. A combined standard of reference was applied, which consisted of histopathology (lymphadenectomy or biopsy) or clinical or radiological follow-up for at least 12 months. RESULTS the mean FDG uptake over the clinicopatholigical verified FDG avid areas was 4.7 SUV (1.5-9.9 SUV). The region based assessment of diagnostic value, in consideration of the standard of reference, resulted in a sensitivity of 85.7% and a specificity of 96.2% of FDG-PET (n=127) and in a combined sensitivity of 95.5% and a specificity of 89.1% for morphological imaging methods (n=68). Differences between methods did not reach statistical significance (p=1.00, p=0.18). CONCLUSIONS FDG-PET is a highly useful whole body staging method of comparable value compared to conventional imaging methods with restricted field of view. The lessons learned from case series are discussed.