[(18)F]FDG in childhood lymphoma: clinical utility and impact on management

Positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) is a very useful technique for the imaging of lymphomas in the adult population. It provides unique information about the behaviour of malignant cells and contributes to more accurate staging of the illness and better assessment of response to therapy. The purpose of this study was to evaluate the usefulness of FDG PET in childhood lymphoma compared with conventional imaging methods (CIMs) and clinical data. Between July 1998 and August 2001, 42 FDG PET examinations were performed using a dedicated PET system (27 examinations) or a hybrid coincidence PET system (15 examinations) for initial tumour staging ( n=7), restaging ( n=5) or assessment of response to therapy or residual masses ( n=30) in 27 children with Hodgkin's disease (HD) ( n=20) or non-Hodgkin's lymphoma (NHL) ( n=7). FDG PET results were compared with CIM findings and clinical data. Since 2000, a standardised questionnaire for evaluation of the clinical impact of FDG PET on both staging and therapy has been sent to the 16 referring physicians and 13 have replied. In all children, FDG PET was performed without any side-effects. FDG PET was found to be very sensitive (Se=12/12) for staging and restaging of the illness, showing more lesions than CIMs, with a 50% patient upstaging rate (6/12). It was very accurate for monitoring response to therapy and for characterisation of residual masses. False-positive results were observed in two NHL patients with thymic uptake and one false-negative result was obtained in a patient whose NHL relapsed 1 month after a negative FDG PET. The questionnaire emphasised the impact of FDG PET on clinical management, which was modified on the basis of the FDG PET results in 23% of patients. As previously demonstrated in the adult population, FDG PET appeared to be a very sensitive imaging technique for staging and restaging of lymphoma in children and was very useful for monitoring the response to therapy.

[18F]-FDG positron imaging in clinical management of lymphoma patients

[18F]-FDG is a glucose analogue labelled with a short-lived positron emitter. During the past decade, it has been proposed to detect in vivo lymphoma lesions with PET, a new non-invasive imaging modality. We aimed at reviewing the current experience with FDG in several clinical settings of lymphoma. Due to the lack of specificity of FDG for lymphoma, histology remains compulsory to establish the diagnosis. Nevertheless, in the case of AIDS, FDG imaging has been proposed to differentiate lymphoma and opportunistic infections in brain lesions. To explore lymphoma extension, FDG-PET highlights more lesions than CT or the clinical examination and results in upstaging 13% of cases. It could also be used for selecting a site for biopsy when the location considered first clinically is difficult to access. Staging lymphoma with FDG-PET also provides baseline images for subsequent evaluation of therapy, which is one of the most promising indications: a negative scan predicts response to therapy and subsequent remission with a predictive value of 89%, and a positive scan either reflects resistance or predicts relapse with a predictive value of 83%. The current achievement of FDG imaging is the early detection of recurrence or of viable tissue in residual masses that remain several months after treatment. Both its sensitivity (84%) and its specificity (95%) overwhelm the values of conventional imaging, mainly CT and gallium-67 scintigraphy. When PET, as a new clinical imaging modality, is not yet widely demanded by clinicians and/or the number of FDG examinations is less than 500 per year, a 'hybrid' gamma-camera or CDET can be an alternative to dedicated PET. For 3 years, we have been using FDG-CDET in the 2D mode without attenuation correction, and obtained the following accuracy in a total of 40 examinations that could be evaluated: 85% for assessment of chemotherapy and 92% to detect recurrences and evaluate residual masses. Our preliminary results also stress the interest in FDG examination in childhood lymphoma, with the same indications as in adults.

Impact of [18F]-fluorodeoxyglucose ([18F]-FDG) imaging in sarcoidosis: unsuspected neurosarcoidosis discovered by [18F]-FDG PET and early metabolic response to corticosteroid therapy

A 46-year-old woman, with biopsy proven pulmonary sarcoidosis, was referred for an [18F]-FDG PET/CT scan that depicted multivisceral involvement and an unusual [18F]-FDG focus located in the pituitary fossa consistent with pituitary sarcoidosis. This was confirmed by decreased antidiuretic hormone blood levels and contrast-enhanced CT scan. This unsuspected neurosarcoidosis prompted corticosteroid therapy. A [18F]-FDG-PET/CT examination performed 10 weeks after initiation of treatment revealed complete recovery. It is suggested that the skull base should be included in the PET scanning of patients with sarcoidosis. [18F]-FDG imaging may be useful in the early evaluation of response to treatment.

The sentinel lymph node procedure for patients with preoperative diagnosis of ductal carcinoma in situ: risk factors for unsuspected invasive disease and for metastatic sentinel lymph nodes

BACKGROUND

Occult invasive disease could be found at definitive histology in patients initially diagnosed with large ductal carcinoma in situ (DCIS). Sentinel lymph node (SLN) biopsy is a reliable and minimally invasive procedure providing axillary information and avoiding a second operation in this particular group of patients. The aim of our study was to assess the value of SLN biopsy in patients with large DCIS who are at highest risk for being upstaged to invasive carcinoma.

PATIENTS AND METHODS

The study included 195 patients diagnosed with DCIS upon initial core biopsy and undergoing SLN biopsy. Many features were correlated with the presence of unsuspected invasive disease and positive SLN biopsy using univariate and multivariate analyses.

RESULTS

Of the 110 patients with pure DCIS, seven patients (6%) had a metastatic lymph node; 31 patients (16%) were found to have invasive disease upon final histology. Univariate analysis of predictors of unsuspected invasive carcinoma showed that patients having a preoperative biopsy that indicated DCIS with microinvasion (DCISM) or large DCIS were at a higher risk of invasive carcinoma after histological examination of the operative specimen. Of the 31 patients who were upstaged to invasive carcinoma at final histology, seven patients (22%) had a positive SLN biopsy. The analysis of predictors of positive SLN in our study shows that diffuse DCIS requiring mastectomy is the main risk factor for SLN metastasis.

CONCLUSION

There are no real predictive factors for invasive disease in patients with an initial diagnosis of DCIS or DCISM. Our study supports the value of SLN biopsy in patients with a preoperative DCISM biopsy or patients with a large pure DCIS biopsy requiring mastectomy.

[18F]-FDG uptake in soft tissue dermatome prior to herpes zoster eruption: an unusual pitfall

Authors report on a case of [18F]-fluorodeoxyglucose ([18F]-FDG) uptake in the soft tissue of a patient referred for [18F]-FDG coincidence detection emission tomography (CDET) in a search for recurrence of colorectal cancer. A herpes zoster eruption occurred in the same site within two days, but was spontaneously resolved. To the best of our knowledge this is the first description of a false positive [18F]-FDG result in relation to a viral infection of soft tissue. It shows that interpretation of subcutaneous foci has to be cautious in patients with or without a past history of herpes zoster even in pain-free areas and prior to skin eruption.

MRI and FDG PET/CT findings in a case of probable Heidenhain variant Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is a neurodegenerative disease caused by the accumulation of a pathogenic isoform of a prion protein in neurons that is responsible for subacute dementia. The Heidenhain variant is an atypical form of CJD in which visual signs are predominant. This is a report of the case of a 65-year-old man with probable CJD of the Heidenhain variant, with topographical concordance between findings on magnetic resonance imaging (MRI) and 18F-fluorodeoxyglucose (FDG) photopenic areas on positron emission tomography (PET)/computed tomography (CT) for cortical parietooccipital lesions.

Tomographie par émission de positons et fusion d'images de simulation virtuelle par tomodensitométrie. Impact sur la planification de la radiothérapie conformationnelle des cancers de l'œsophage

PURPOSE

To study the impact of fused (18)F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on conformal radiation therapy (CRT) planning for patients with esophageal carcinoma.

PATIENTS AND METHODS

Thirty-four patients with esophageal carcinoma were referred for concomitant radiotherapy and chemotherapy with radical intent. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same radiation treatment position. PET-images were coregistered using five fiducial markers. Target delineation was initially performed on CT images and the corresponding PET data were subsequently used as an overlay to CT data to define the target volume.

RESULTS

FDG-PET identified previously undetected distant metastatic disease in 2 patients, making them ineligible for curative CRT. The Gross Tumor Volume (GTV) was decreased by CT and FDG image fusion in 12 patients (35%) and was increased in 7 patients (20.5%). The GTV reduction was >or=25% in 4 patients due to reduction of the length of the esophageal tumor. The GTV increase was >or=25% with FDG-PET in 2 patients due to the detection of occult mediastinal lymph node involvement in one patient and an increased length of the esophageal tumor in the other patient. Modifications of the GTV affected the planning treatment volume (PTV) in 18 patients. Modifications of delineation of GTV and displacement of the isocenter of PTV by FDG-PET also affected the percentage of total lung volume receiving more than 20 Gy (VL20) in 25 patients (74%), with a dose reduction in 12 patients and a dose increase in 13 patients.

CONCLUSION

In our study, CT and FDG-PET image fusion appeared to have an impact on treatment planning and management of patients with esophageal carcinoma related to modifications of GTV. The impact on treatment outcome remains to be demonstrated.

Use of a coincidence gamma camera to detect primary tumor with 18fluoro-2-deoxy-glucose in cervical lymph node metastases from an unknown origin

This study was performed to evaluate the ability of a dual-head gamma camera with 18fluoro-2-deoxy-glucose coincidence detection emission tomography (FDG-CDET) to detect primary tumors in patients with cervical lymph node metastases of head and neck squamous cell carcinoma from an unknown origin. From 60 patients with untreated head and neck squamous cell carcinoma, we selected 4 in whom no evidence of the primary's origin was found by the conventional methods used for the evaluation of head and neck tumors. In addition to the panendoscopy, chest radiography, a computed tomography (CT) scan, and FDG-CDET were performed. Both FDG-CDET and the CT scan located cervical lymph node metastases. In addition, FDG-CDET located the primary tumor in 3 of the 4 patients, and the tumors were confirmed with histopathologic findings. In contrast, the CT scan detected the primary tumor in none of them. FDG tomography performed on a coincidence gamma camera appears to be a successful new tool in detecting occult primary tumors in head and neck carcinoma, and is useful in guiding endoscopic biopsies. It has, further, the important potential ability to detect distant metastases on whole body images.

Tomographie par émission de positons et détection en coïncidence (TEDC) et recalage d'images de simulation virtuelle par tomodensitométrie. Impact sur la planification de la radiothérapie conformationnelle des cancers bronchiques non à petites cellules

To report a retrospective study concerning the impact of fused 18F-fluorodeoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on three-dimensional conformal radiation therapy (3D-CRT) planning for patients with non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

One hundred and one patients consecutively treated for stages I-III NSCLC were studied. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same radiation treatment position. Images were coregistered using five fiducial markers. Target volume delineation was initially performed on the CT images and the corresponding FDG-PET data were subsequently used as an overlay to the CT data to define target volume.

RESULTS

FDG-PET identified previously undetected distant metastatic disease in 8 patients making them ineligible for curative CRT (one patient presented some positive uptakes corresponding to concomitant pulmonary tuberculosis). Another patient was ineligible for curative treatment because fused CT/PET images demonstrated excessively extensive intrathoracic disease. The gross tumor volume (GTV) was decreased by CT/PET image fusion in 21 patients (23%) and was increased in 24 patients (26%). The GTV reduction was > or = 25% in 7 patients because CT/PET image fusion reduced pulmonary GTV in 6 patients (3 patients with atelectasis) and mediastinal nodal GTV in 1 patient. The GTV increase was > or = 25% in 14 patients due to an increase of the pulmonary GTV in 11 patients (4 patients with atelectasis) and detection of occult mediastinal lymph node involvement in 3 patients. Among 81 patients receiving a total dose > or = 60 Gy at ICRU point, after CT/PET image fusion, the percentage of total lung volume receiving more than 20 Gy (VL20) increased in 15 cases and decreased in 22 cases. The percentage of total heart volume receiving more than 36 Gy increased in 8 patients and decreased in 14 patients. The spinal cord volume receiving at least 45 Gy (2 patients) decreased. After multivariate analysis, one single independent factor made significant effect of FDG/PET on the modification of the size of the GTV: tumor with atelectasis (P = 0.0001). Conclusion. - Our study confirms that integrated hybrid PET/CT in the treatment position and coregistered images have an impact on treatment planning and management of patients with NSCLC. FDG images using dedicated PET scanners with modern image fusion techniques and respiration-gated acquisition protocols could improve CT/PET image coregistration. However, prospective studies with histological correlation are necessary and the impact on treatment outcome remains to be demonstrated.

[(18F)-fluoro-2-deoxyglucose PET in imaging of gynecologic cancers]

Although gynaecological cancers are not currently part of the clinical indications in the French registration for [18F]-fluoro-2-deoxyglucose (FDG), various studies indicate in this context a potential clinical benefit of imaging with this radiopharmaceutical and PET, a new imaging modality that can be performed either with a dedicated machine or with a "hybrid" gamma-camera (CDET). The potential indications of FDG-PET in mammary, ovarian or cervical cancers are reviewed according to the diagnostic phase: screening, tumour characterisation, staging, therapeutic follow-up and search for recurrence. By pooling the published results, the accuracy of FDG-PET could be estimated with a reasonable precision in various clinical settings: characterisation of a breast tumour (598/696 = 86%), lymph node invasion in breast cancer (525/602 = 87%), recurrence of breast cancer (114/127 = 90%), characterisation of adnexal masses (130/176 = 78%), recurrence of ovarian cancer (152/172 = 88%), lymph node invasion in cervical cancer (98/103 = 95%). Authors also present original data concerning their experience of recurrence detection with CDET in breast or ovarian cancers. In 44 patients suspicious of recurrence of breast cancer, FDG-CDET sensitivity was 94%, specificity 82% and accuracy 91%; in 18 patients suspicious of recurrence of ovarian cancer, specificity, sensitivity and accuracy were 100%. The impact of dedicated PET and CDET examinations performed by our team during year 2000, led, according to 63 forms returned to us, to a modification of stage in 48% of breast cancers, 36% of ovarian cancers, 43% of cervical cancers and above all induced a modification in patients' management in respectively 69%, 64% and 60% of cases, more than the average rate in cancer patients which was 50%. No significant difference was observed between clinical impact of dedicated PET and CDET examinations.

Évaluation de la radiosensibilité tumorale par l'imagerie fonctionnelle et métabolique : de la recherche à l'application clinique. Revue de la littérature

During the last half of century considerable research on radiosensitivity biomarkers has been published. However, to date there is no non-invasive marker of cellular radiosensitivity identified for clinical routinely use. In this review, the main functional and metabolic imaging isotopic techniques for tumor radiosensitivity that have been explored over the last years are being described. This indirect evaluation fall into 3 topics associated with tumor proliferation rate or apoptosis, tumor hypoxic fraction, neoangiogenesis and the intrinsic radiosensitivity of clonogenic tumor cells. The final objective of the radiosensitivity monitoring during radiotherapy would be to adapt treatment strategy for overcoming the identified radioresistance mechanism such as hypoxia by the addition of radiosensitisers for example. This would allow better tumor control rather than continue inefficient and costly treatment delivery, which in addition could compromise outcome.

[18F-FDG PET and bone scintigraphy to search for bone metastasis of lung cancer]

Initial staging of lung cancer is essential to determine the appropriate therapeutic strategy. 18F-FDG PET is currently considered to be the gold standard. 99mTc bisphonate bone scintigraphy has long been indicated to search for bone metastases but it is not know whether this exploration adds further information after an 18F-FDG PET scan. In order to answer this question, two observers unaware of the clinical situation reread PET scans and bone scintigraphies and results compared with other imaging findings. Between February 2001 and March 2004, 39 patients (13F, 26M, 62 +/- 11 yr) underwent 18FFDG PET and bone scintigraphy (mean interval 17 +/- 17 d). When the two explorations agreed for the diagnosis of bone extension, we considered that bone scintigraphy added nothing. When the two explorations were in disagreement, the other imaging examinations, the clinical features and laboratory results during the five-month minimal follow-up were used to establish the reference diagnosis. 18F-FDG PET and bone scintigraphy were in agreement in 29 patients (74%) with positive results in 12 (31%) and negative results in 17 (43%). The two explorations were in disagreement in 10 patients (26%). Among the five disagreement cases with positive bone scintigraphy and no bone anomaly on the 18F-FDG PET, the anomalies were benign and explained by clinical features (3 patients) or were not confirmed by the clinical course and laboratory results (2 patients). Among the 5 cases with a bone anomaly on the 18F FDG PET, no metastasis could be identified during clinical follow-up. Bone scintigraphy does not enable identification of any bone metastases which were not recognized on the PET scan and therefore should not be performed systematically. Using a computed tomography scan with the 18F-FDG PET could further limit the contribution of bone scintigraphy by providing more precision concerning foci identified on the PET scan.

Valoración de un tumor neuroendocrino mediante gammagrafía con 111In-pentetreótido y PET con 18F-FDOPA y 18F-FDG

We present the case of a 67 year old patient diagnosed of a neuroendocrine carcinoid tumour of the small intestine. The tumour and subsequent metastases were resected previously by surgery, but a new recurrence was suspected. CT showed left adrenal enlargement. 18F-FDG PET was normal and 111In pentetreotide scintigraphy showed liver and left diaphragmatic uptake. 18F-FDOPA PET showed uptake foci in liver and left diaphragm and also in left adrenal gland, retro urinary bladder area and multiple foci in abdominopelvic region, suggesting a peritoneal carcinomatosis. 18F-FDOPA PET was the first imaging modality to assess the extensiveness of the disease that was confirmed six month later by CT. Neuroendocrine tumors are a heterogeneous group of neoplasia. They are studied by conventional radiologic and functional techniques of nuclear medicine. This case illustrates the need to use the different techniques and tracers according to the characteristics of the tumor to be studied to thus improve the diagnostic and prognostic performance.

[Value of [18F]-fluorodeoxyglucose (FDG) positron emission tomography in digestive cancerology]

COLORECTAL CANCERS: FDG-PET is a very effective tool in the follow-up of colorectal cancer for the early detection of recurrences, the search for other localisations in case of resectable lesions and for the evaluation of therapies. For the other digestive cancers, the data in the literature are less abundant and they do not yet have Marketing Authorization in France. OESOPHAGEAL CANCER: FDG-PET appears very promising for staging and detection of recurrences of oesophageal carcinomas. Pancreatic cancer Although the indication is difficult, FDG-PET appears superior to morphological techniques for the characterization and the locoregional staging of pancreatic tumours. BILARY AND GASTRIC CARCINOMAS: FDG-PET is promising but its role has to be confirmed in larger series for the detection of biliary and gastric carcinomas. OTHER DIGESTIVE TUMOURS: In cases of hepatocarcinoma, FDG-PET appears efficient only in cases of undifferentiated tumours, and in cases of malignant neuroendocrine digestive tumours, is useful in combination with somatostatin receptor imaging.

Fluorocholine (18F) and sodium fluoride (18F) PET/CT in the detection of prostate cancer: prospective comparison of diagnostic performance determined by masked reading

AIM

The aim of this paper was to compare the diagnostic performance of positron emission tomography/computed tomography (PET/CT) with fluorocholine (18F) (FCH) or fluoride(18F) (FNa) for the detection of bone metastasis in patients with prostate cancer complaining from osteoarticular pain, taking into account whether they were referred for initial staging or recurrence localization. The initial hypothesis was that FCH site-based specificity would be superior to that of F Na, with no loss in sensitivity.

METHODS

Forty-two patients were enrolled in this prospective study, underwent both PET/CTs and were then followed-up for at least 6 months. The standard of truth (SOT) about the presence/absence and location of bone metastasis could be determined in 40 patients, by 2 independent medical assessors, blinded to the results of both PET/CTs. The comparison was performed according to the guideline of the European Medicines Agency, i.e. based on the results of blind reading with SOT as reference.

RESULTS

Bone extension was present in 22 patients and absent in 18. Patient-based performance for FCH vs. FNa was 91% vs. 91% for sensitivity, 89% vs. 83% for specificity and 90% vs. 88% for accuracy (no significant difference). Of 360 skeletal sites, 68 were malignant and 292 non-invaded. There was no significant difference in site-based performance in the group of patients referred at initial staging, but in the group of patients referred for suspicion of recurrence, FCH was significantly more specific than FNa (96% vs. 91%, P=0.033 with Obuchowski's correction) while sensitivity was the same, 89%.

CONCLUSION

Both radiopharmaceuticals, based on a very different metabolic approach, showed good diagnostic performance. If FCH is available, it should be preferred in patients after initial treatment.