FDG-PET for detection of pulmonary metastases from malignant primary bone tumors: comparison with spiral CT

BACKGROUND

The purpose was the comparison of positron emission tomography using F-18-fluorodeoxy-glucose (FDG-PET) and spiral thoracic CT to detect pulmonary metastases from malignant primary osseous tumors.

PATIENTS AND METHODS

In 71 patients with histologically confirmed malignant primary bone tumors (32 osteosarcomas, 39 Ewing's sarcomas) 111 FDG-PET examinations were evaluated with regard to pulmonary/pleural metastases in comparison with spiral thoracic CT. Reference methods were the clinical follow-ups for 6-64 months (median 20 months) or a histopathologic analysis.

RESULTS

In 16 patients (23%) reference methods revealed a pulmonary/pleural metastatic disease. FDG-PET had a sensitivity of 0.50, a specificity of 0.98, and an accuracy of 0.87 on a patient based analysis. Comparable values for spiral CT were 0.75, 1.00, and 0.94. It was shown that no patient who had a true positive FDG-PET had a false negative CT scan, nor was a pulmonary metastases detected earlier by FDG-PET than by spiral CT.

CONCLUSIONS

There seems to be a superiority of spiral CT in the detection of pulmonary metastases from malignant primary bone tumors as compared with FDG-PET. Therefore, at present a negative FDG-PET cannot be recommended to exclude lung metastases. However, as specificity of FDG-PET is high, a positive FDG-PET result can be used to confirm abnormalities seen on thoracic CT scans as metastatic.

Characterization of 3-[123I]iodo-L-alpha-methyl tyrosine ([123I]IMT) transport into human Ewing's sarcoma cells in vitro

3-[(123)I]Iodo-L-alpha-methyl tyrosine ([(123)I]IMT) scintigraphy of extracranial malignant tumors has been described, but little is known about the transport systems involved in [(123)I]IMT uptake into extracranial tumor cells. Here, the precise kinetics of [(123)I]IMT transport into human Ewing's sarcoma cells (VH-64) was determined. The apparent Michaelis constant was of high affinity value (K(m)=41.7+/-3.9 microM) and maximum transport velocitiy amounted to V(max)=20.7+/-0.6 nmol x mg protein(-1) x 10 min(-1). Inhibition experiments revealed the predominance of [(123)I]IMT uptake via sodium-independent system L.

Evaluation of chemotherapy response in primary bone tumors with F-18 FDG positron emission tomography compared with histologically assessed tumor necrosis

PURPOSE

The purpose of this study was to evaluate the potential of positron emission tomography using F-18-fluoro-2-deoxy-D-glucose (FDG PET) to assess the chemotherapy response of primary osseous tumors compared with the degree of necrosis determined histologically.

PATIENTS AND METHODS

Seventeen patients with primary bone tumors (11 osteosarcomas, 6 Ewing's sarcomas) were examined using FDG PET and planar bone scintigraphy before neoadjuvant chemotherapy and before surgery. Tumor response was classified histologically according to Salzer-Kuntschik (grades I-II: good response; grades IV-VI: poor response). In both imaging methods, quantification was performed using tumor to nontumor ratios (T:NT).

RESULTS

Histologically, 15 patients were classified as having good responses (grade I, n = 1; grade II, n = 6; grade III, n = 8) and two as having poor responses (grades IV and V). FDG PET showed more than a 30% decrease in T:NT ratios in all patients who had good responses. However, three of these patients had increasing bone scintigraphy T:NT ratios, and another five had decreasing ratios of less than 30%. The patients with poor responses had increasing T:NT ratios and decreasing ratios of less than 30%, respectively, using both imaging methods.

CONCLUSIONS

FDG PET seems to be a promising tool for evaluating the response of primary osseous tumors to chemotherapy. In this preliminary study, FDG PET was superior to planar bone scintigraphy.

FDG-PET for detection of osseous metastases from malignant primary bone tumours: comparison with bone scintigraphy

The purpose of this study was to compare positron emission tomography using fluorine-18 fluorodeoxyglucose (FDG-PET) and technetium-99m methylene diphosphonate (MDP) bone scintigraphy in the detection of osseous metastases from malignant primary osseous tumours. In 70 patients with histologically proven malignant primary bone tumours (32 osteosarcomas, 38 Ewing's sarcomas), 118 FDG-PET examinations were evaluated. FDG-PET scans were analysed with regard to osseous metastases in comparison with bone scintigraphy. The reference methods for both imaging modalities were histopathological analysis, morphological imaging [additional conventional radiography, computed tomography (CT) or magnetic resonance imaging (MRI)] and/or clinical follow-up over 6-64 months (median 20 months). In 21 examinations (18%) reference methods revealed 54 osseous metastases (49 from Ewing's sarcomas, five from osteosarcomas). FDG-PET had a sensitivity of 0.90, a specificity of 0.96 and an accuracy of 0.95 on an examination-based analysis. Comparable values for bone scintigraphy were 0.71, 0.92 and 0.88. On a lesion-based analysis the sensitivity of FDG-PET and bone scintigraphy was 0.80 and 0.72, respectively. Analysing only Ewing's sarcoma patients, the sensitivity, specificity and accuracy of FDG-PET and bone scan were 1.00, 0.96 and 0.97 and 0.68, 0.87 and 0.82, respectively (examination-based analysis). None of the five osseous metastases from osteosarcoma were detected by FDG-PET, but all of them were true-positive using bone scintigraphy. In conclusion, the sensitivity, specificity and accuracy of FDG-PET in the detection of osseous metastases from Ewing's sarcomas are superior to those of bone scintigraphy. However, in the detection of osseous metastases from osteosarcoma, FDG-PET seems to be less sensitive than bone scintigraphy.

High-activity samarium-153-EDTMP therapy in unresectable osteosarcoma

Despite highly efficacious chemotherapy, patients with osteosarcomas still have a poor prognosis if adequate surgical control cannot be obtained. We applied high-activity Sm-153-EDTMP therapy within a multimodal therapy concept to improve local control of an unresectable osteosarcoma with poor response to initial polychemotherapy. A 21-year-old woman with an extended, unresectable pelvic osteosarcoma and multiple pulmonary metastases was treated with high-activity of Sm-153- EDTMP (150 MBq/kg BW, total 8.1 GBq). Afterwards external radiotherapy of the primary tumor site was performed and polychemotherapy was continued, followed by autologous peripheral blood stem cell reinfusion. Within 48 h after Sm-153-EDTMP application the patient had complete pain relief. After three weeks the response was documented by 3-phase Tc-99m-MDP bone scintigraphy (primary tumor and metastases: decreased tracer uptake), whole-body F-18-FDG-PET (primary tumor and metastases: diminution of glucose metabolism) and thoracic CT (metastases: reduction of size). The present case warrants further evaluation of feasibility and efficacy of this multimodal therapy combination of high-activity Sm-153-EDTMP therapy, external radiation, polychemotherapy and stem cell support for unresectable osteosarcomas.

Reconstructive treatment of sclerosing osteomyelitis of the entire femur of 30 years' duration with avoidance of segmental resection

We describe the successful operative treatment of a patient with chronic sclerosing osteomyelitis of the femur in which en bloc resection was avoided. Therapy consisted of combined endoscopic, computed tomography and bone scan-guided fenestration and intramedullary reaming, with removal of all sclerotic zones and normalization of the cortical thickness. An adequate supply of oxygen to the area was ensured by improved vascularisation and the application of hydrogen peroxide. At the medium term follow-up no recurrence was seen, and hip and knee function was normal.

Determination of extent and activity with radionuclide imaging in Erdheim-Chester disease

Erdheim-Chester disease usually involves the diaphyseal and metaphyseal regions of tubular bones and various visceral organs. A 56-year-old woman presented with the histologically confirmed diagnosis of Erdheim-Chester disease. A Tc-99m MDP bone scan revealed the entire extent of the skeletal disease and showed unusual involvement of the epiphyses and axial skeleton. In addition to MRI, a Ga-67 citrate scan including SPECT showed extensive soft-tissue infiltration of different organs. Both Tc-99m MDP and Ga-67 scintigraphy are useful tools in determining the distribution of this rare disease.

[Role of 18F-FDG positron emission tomography in surgical evaluation]

Positron emission tomography (PET) using F-18-fluorine-deoxy-glucose (FDG) as a metabolic marker is a non-invasive diagnostic tool that can distinguish malignant processes from normal tissue by means of increased glycolysis. Since the advent of whole-body scanning, its higher spatial resolution compared with conventional scintigraphic methods leads to widespread applications of FDG-PET in oncology. The clinical value of FDG-PET has been proven for a number of tumor entities. As will be shown in the following review for bronchial, colorectal and pancreatic malignomas, functional imaging with FDG-PET provides relevant diagnostic information complementary to morphologic imaging.

High-Activity Samarium-153-EDTMP Therapy in Unresectable Osteosarcoma

Despite highly efficacious chemotherapy, patients with osteosarcomas still have a poor prognosis if adequate surgical control cannot be obtained. We applied high-activity Sm-153-EDTMP therapy within a multimodal therapy concept to improve local control of an unresectable osteosarcoma with poor response to initial polychemotherapy. A 21-yearold woman with an extended, unresectable pelvic osteosarcoma and multiple pulmonary metastases was treated with high-activity of Sm-153- EDTMP (150 MBq/kg BW, total 8.1 GBq). Afterwards external radiotherapy of the primary tumor site was performed and polychemotherapy was continued, followed by autologous peripheral blood stem cell reinfusion. Within 48 h after Sm-153-EDTMP application the patient had complete pain relief. After three weeks the response was documented by 3-phase Tc-99m-MDP bone scintigraphy (primary tumor and metastases: decreased tracer uptake), whole-body F-18-FDG-PET (primary tumor and metastases: diminution of glucose metabolism) and thoracic CT (metastases: reduction of size). The present case warrants further evaluation of feasibility and efficacy of this multimodal therapy combination of high-activity Sm-153-EDTMP therapy, external radiation, polychemotherapy and stem cell support for unresectable osteosarcomas.

Simultaneous evaluation of fatty acid metabolism and myocardial flow in an explanted heart

The biodistribution of the fatty acid analog [131I]PHIPA 3-10, was compared to the flow tracer 99mTc-sestamibi by quantitative analysis in a dual-isotope study performed during a heart transplantation.

METHODS

Iodine-131-PHIPA 3-10 and 99mTc-sestamibi were injected simultaneously approximately 20 min prior to the start of surgical procedure. Scintigraphic images of the sliced explanted heart were compared to the preoperative in vivo scans using [123I]PHIPA 3-10, 201TI and 99mTc-sestamibi. In 14 tissue samples of the explanted heart, the radioactive contents from [131I]PHIPA 3-10 and 99mTc-sestamibi were calculated as %ID/g-values and correlated with the corresponding histology.

RESULTS

In the preoperative scans, a mismatch of fatty acid uptake and perfusion ([123I]PHIPA 3-10 > flow) was observed which indicated residual viable myocardium, while a matched defect was associated with scar. In viable myocardium, there was a significantly higher accumulation of [131I]PHIPA 3-10 compared to 99mTc-sestamibi (mean 5.9 x 10(-3) versus 2.7 x 10(-3)%ID/g),whereas in scars the uptake of both tracers was comparable (1.2 x 10(-3) versus 1.4 x 10(-3)%ID/g).

CONCLUSION

Myocardial viability can be defined more accurately with radioiodinated PHIPA 3-10 than with 99mTc-sestamibi. The differences of biodistribution in viable myocardium and scars indicate that not only perfusion but also the metabolic state of the myocardium can be evaluated with radioiodinated PHIPA 3-10.

Structure distribution relationship of iodine-123-iodobenzamides as tracers for the detection of melanotic melanoma

The influence of systematic structure variations on the biodistribution of positional isomers of N-(N'-dialkylaminoethylene)-[123I]iodobenzamide (ABA) derivatives in melanoma-bearing animals was investigated.

METHODS

Radioiodination of six bromo benzamide precursors was achieved by Cu(1)-assisted nonisotopic halogen exchange. Organ distribution, scintigraphic and metabolic studies were performed in nude mice bearing a human melanotic MM (SK-MEL 25). A patient suffering from melanotic melanoma underwent scintigraphy with a [123I]iodobenzamide.

RESULTS

High radiochemical yields of 80%-95% and specific activities of > 5 TBq/ mumole were obtained. Animal studies revealed specific tumor uptake of all compounds with longest retention of the most lipophilic derivative p-[123I]ABA 2-2. At shorter times, however, o-[123I]ABA 2-2 exhibited the highest tumor uptake (8.9% ID/g, 1 hr p.i., 10.9% ID/g, 4 hr p.i.). Metabolization of o-[123I]ABA 2-2, mainly to o-[123I]iodohippuric acid (OIH), followed by fast renal excretion of the metabolites lead to tumor/nontumor ratios (T/NT) of > 400 for tumor/blood, and > 70 for tumor/liver at 48 h p.i. Unknown metastases could be localized in a patient using o-[123I]ABA 2-2.

CONCLUSION

The effects of the structure variation of iodobenzamides on their lipophilicity, metabolism and thus pharmacokinetics lead to the suggestion of o-[123I]ABA 2-2 as a favorable melanoma imaging agent.

Use of various diagnostic methods in a patient with Gaucher disease type I

A series of plain radiographs, bone scans, bone marrow scans, and MRIs is reported in a patient with Gaucher disease type I, in whom two episodes of acute bone crisis developed during a 6-year period of follow-up. Acute bone crisis and global indolent bone marrow displacement could both be assessed by bone marrow scintigraphy, whereas MRI could better clarify the corti-comedullary alteration after bone infarction. Thus, MRI and bone marrow scintigraphy could be used as complementary imaging methods in the management of patients with Gaucher disease.

[Positron emission tomography for primary tumor detection in lymph node metastases with unknown primary tumor]

In a prospective study 16 patients with cervical lymph node metastases from an occult tumor were analyzed by (18F)FDG positron emission tomography (PET). The aim of this study was to locate the primary tumor. In 7 patients a localized increase in activity was seen on PET, with this site of activity histologically proven in 4 patients. No biopsies were taken in 3 patients in areas with a high risk of complications. In a follow-up procedure at 2-22 months after primary radiation therapy in the other 9 patients, no primary tumor has been identified to date.

Synthesis, characterization and biodistribution of neutral and lipid-soluble 99mTc-bisaminoethanethiol spiperone derivatives: possible ligands for receptor imaging with SPECT

Using parts of the molecular structure of spiperone, two new ligand systems for complexation with [99mTc]technetium were prepared in order to develop potential receptor imaging agents for single photon emission computer tomography (SPECT). The bis-aminoethanethiols (BAT): 1-benzyl-4-(2-mercapto-2-methyl-4-aza-pentyl)-4-(2-mercapto-2-methyl- propylamino)-piperidine (benzylpiperidyl-BAT, BP-BAT) and 1-[3-(4-fluorobenzoyl)-propyl]-4-(2-mercapto-2-methyl-4-aza-pentyl)-4- (2-mercapto-2-methyl-propyl-amino)-piperidine (butyrophenoylpiperidyl-BAT, BUP-BAT) form stable, neutral and lipid soluble complexes with [99mTc]technetium at pH > or = 11 using SnCl2 as reducing agent in nearly quantitative radiochemical yields. Biodistribution of 99mTc-BP-BAT and 99mTc-BUP-BAT in rats showed a moderate clearance from blood and low uptake and retention in the liver, whereas brain uptake was moderate, however with prolonged brain retention. On the other hand, significant accumulations and retentions were observed in heart, kidney and lung with increasing oxygen/blood ratios up to 24 h. Within 24 h p.i. 22 and 29% of the injected dose (i.d.) of 99mTc-BP-BAT and 99mTc-BUP-BAT were eliminated by hepatobiliary excretion whereas 22% i.d. of both 99mTc-BAT complexes were excreted into the urine. Although first biodistribution studies of 99mTc-BP-BAT and 99mTc-BUP-BAT in rats showed relatively low brain uptake, the high uptake in peripheral, receptor rich organs indicates that compounds of this type may be used as a basis for further structural modification to develop agents with optimal properties for cerebral or peripheral receptor imaging with SPECT.

[The diabetic foot]

Foot disease in patients with diabetes mellitus is multifactorial and results from a combination of peripheral neuropathy, vascular compromise and superimposed infection. Foot complications in diabetic patients are common and account for more hospital days than any other aspects of their disease. Therefore, familiarity with the spectrum of findings in the different imaging modalities appears essential. Radiographically, significant changes include Charcot joints of the tarsus (destructive type) and bone absorption of the forefoot (mutilating type). In diabetic foot problems, magnetic resonance imaging and leukocyte scintigraphy appear to be the most effective tools for detection of osteomyelitis, and a negative study makes osteomyelitis unlikely. However, the findings of both techniques in active, noninfected neuropathic osteoarthropathy may be indistinguishable from those of osteomyelitis.

[67Ga scintigraphy in acute sarcoidosis with Heerfordt's syndrome]

Sarcoidosis is a chronic multisystem disorder of unknown etiology characterized by non-caseating epitheloid granulomas. We report a case of a 29-year old female with acute sarcoidosis and Heerfordt's syndrome (parotid enlargement, anterior uveitis and facial nerve palsy) who had a typical clinical constellation but no histologic criteria of a granulomatous inflammatory process in transbronchial lung biopsy. 67Ga scintigraphy revealed such a typical pattern of accumulation that sarcoidosis could be diagnosed despite negative histological findings.

67Ga-Szintigraphie bei akuter Sarkoidose mit Heerfordt-Syndrom

Die Sarkoidose ist eine chronische Systemerkrankung unbekannter Ätiologie, die durch nichtverkäsende epitheloidzellige Granulome gekennzeichnet ist. Wir berichten über eine 29jährige Patientin mit akuter Sarkoidose und Heerfordt-Syndrom (Parotisschwellung, Iridozyklitis und Fazialisparese), bei der zwar eine typische klinische Befundkonstellation vorlag, die transbronchiale Lungenbiopsie jedoch histologisch keinen granulomatösen Entzündungsprozeß nachweisen konnte. Die 67Ga-Szintigraphie zeigte ein so typisches Anreicherungsmuster, daß trotz negativer Histologie die Diagnose gestellt werden konnte.

[Spinal metastases. Value of diagnostic procedures in the initial diagnosis and follow-up]

In this retrospective study plain radiographs, radionuclide bone scans, computed tomography (CT) and magnetic resonance (MRT) examinations of 115 patients with metastatic carcinoma of the spine were analyzed. In 32 patients metastases were proven histologically and in the remainder by follow-up studies. Altogether, 513 vertebrae were evaluated. Forty-one patients had histologically proven breast cancer, 14 renal cell carcinoma, 11 prostate cancer, 8 melanoma. 8 tumors of the gastrointestinal system and 7 bronchial carcinoma. Evaluation of the plain films showed that the initial site of metastasis (n = 463) was the vertebral body in 441 cases and the pedicles in 294 cases. In CT scans most of the lesions confined to one part of the vertebral body (36 of 98) were localized in the posterior part. Twelve percent of the metastases were diagnosed with conventional radiography and 17% of those diagnosed with CT were not detected in skeletal scintigraphy. MRI was rarely used in diagnosing occult vertebral metastases (n = 37); 22% of the metastases demonstrated by MRI were not detected in skeletal scintigraphy. We concluded that only in 63.8% was the pedicle sign the initial site of metastasis on plain films. Bone scans and plain films are the most important diagnostic procedures for detecting and monitoring vertebral metastases. CT and MRI are only needed in patients with neurological symptoms and persistent pain.

Scintigraphic detection of osteomyelitis in osteopetrosis

METHODS AND RESULTS

The diagnosis of osteomyelitis in severe osteopetrosis may be difficult since altered bone architecture and fractures veil the typical radiographic signs of inflammation. We present a case of adult osteopetrosis with questionable clinical and radiographic signs of two osteomyelitic foci in the foot.

CONCLUSION

Despite severe skeletal disease, the combination of skeletal and leukocyte scintigraphy suggested the diagnosis of infection.