Increased bone mineral turnover without increased glucose utilization in sclerotic and hyperplastic change in fibrous dysplasia

Comparison of 18 F-FAPI and 18 F-FDG PET/CT in a Patient With Fibrous Dysplasia

ABSTRACT

A 16-year-old woman presented with an acute headache on the left side. A head CT scan revealed bone destruction in the skull. Subsequent 18 F-FDG and 18 F-FAPI PET/CT scans were performed within a week. The 18 F-FDG PET/CT indicated mild uptake in the regions of bone destruction, whereas the 18 F-FAPI PET/CT displayed significant tracer accumulation. The patient was ultimately diagnosed with fibrous dysplasia.

PET/CT and PET/MRI in ophthalmic oncology (Review)

Orbital and ocular anatomy is quite complex, consisting of several tissues, which can give rise to both benign and malignant tumors, while several primary neoplasms can metastasize to the orbital and ocular space. Early detection, accurate staging and re-staging, efficient monitoring of treatment response, non-invasive differentiation between benign and malignant lesions, and accurate planning of external radiation treatment, are of utmost importance for the optimal and individualized management of ophthalmic oncology patients. Addressing these challenges requires the employment of several diagnostic imaging techniques, such as high-definition digital fundus photography, ultrasound imaging, optical coherence tomography, optical coherence tomography (OCT)-angiography, computed tomography (CT) and magnetic resonance imaging (MRI). In recent years, technological advances have enabled the development of hybrid positron emission tomography (PET)/CT and PET/MRI systems, setting new standards in cancer diagnosis and treatment. The capability of simultaneously targeting several cancer-related biochemical procedures using positron emitting-radiopharmaceuticals, while morphologically characterizing lesions by CT or MRI, together with the intrinsic quantitative capabilities of PET-imaging, provide incremental diagnostic information, enabling accurate, highly efficient and personalized treatment strategies. Aim of the current review is to discuss the current applications of hybrid PET/CT and PET/MRI imaging in the management of patients presenting with the most commonly encountered orbital and ocular tumors.

Extensive polyostotic fibrous dysplasia evaluated for malignant transformation with99mTc-MDP bone scan and18F-FDG PET/CT

Fibrous dysplasia accounts for approximately 7% of benign bone tumours and is a developmental disorder of unknown aetiology. Malignant transformation has been reported in 0.4% of all cases of fibrous dysplasia, and the use of ¹⁸F-fludeoxyglucose positron emission tomography/CT scan in the evaluation of malignant transformation has not yet been established. A 72-year-old male with a long-standing history of polyostotic fibrous dysplasia presented with chest and back pain and was evaluated with a ^99mTc-methylene diphosphonate bone scan as well as an ¹⁸F-fludeoxyglucose positron emission tomography/CT scan to define the extent of bone involvement and assess for possible malignant transformation. We present the imaging findings as well as the long-term follow-up of this case.

False Positive FDG PET/CT Resulting from Fibrous Dysplasia of the Bone in the Work-Up of a Patient with Bladder Cancer: Case Report and Review of the Literature

Fibrous dysplasia of the bone (FDB) is a common, genetic, developmental disorder with a benign course. FDB can be seen anywhere throughout the skeleton. It is usually asymptomatic and found incidentally on imaging studies that are performed for other purposes. Although whole body 18 F-flourodeoxyglucose PET/CT (FDG PET/CT) is widely used in tumor imaging, infections and benign pathologies like FDB may cause false positive results. Herein we report the case of a 48-year-old FDB patient with transitional cell carcinoma of the urinary bladder. Restaging FDG PET/CT showed multiple mild to moderate hypermetabolic bone lesions which were initially misinterpreted as bone metastases. In this case report, we aimed to guide physicians in evaluating bone lesions in cancer patients with FDB in the light of the literature.

The role of dual-phase Tc-99m MIBI in the evaluation of potentially operable lesions detected by bone scanning in fibrous dysplasia: a long-term prospective follow-up study

PURPOSE

The aim of this study was to determine the role of whole-body Tc-99m MDP bone scintigraphy (BSc) with dual-phase Tc-99m MIBI scintigraphy (DPMSc) in the assessment of fibrous dysplasia (FD) and the value of DPMSc in the detection of potentially operable lesions for guiding surgical treatment.

METHODS

Twelve patients with histopathologically confirmed FD were evaluated with BSc and DPMSc. The patients were clinically followed up for a mean duration of 75 months. BSc images have been used as a guide to identify the site and the extent of the skeletal involvement. The symptomatic lesions were evaluated with DPMSc.

RESULTS

Forty-three lesions were evaluated in 12 patients. BSc showed increased uptake in all of the lesions, whereas DPMSc findings correlated more accurately with the symptoms. Fifteen symptomatic lesions showed increased Tc-99m MIBI uptake on DPMSc, especially in the early phase of DPMSc. The sensitivity, specificity and accuracy values for the early phase in detecting the symptomatic lesions were 100 and 93%, and for delayed phase were 100 and 98%, respectively.

CONCLUSION

BSc is useful in determining the site and extent of the skeletal involvement, especially in polyostotic FD. It seems that the potentially operable symptomatic lesions may be evaluated more accurately with DPMSc as compared with BSc. In addition, it seems that DPMSc findings correlate with the symptoms of FD, and this relationship may have a role in improving the preoperative assessment for guiding surgical treatment. DPMSc could be useful in the work-up of symptomatic patients if our results are validated in a larger patient series.

Recognition of fibrous dysplasia of bone mimicking skeletal metastasis on 18F-FDG PET/CT imaging

PURPOSE

Fibrous dysplasia of bone (FDB) reveals intense 18F-FDG uptake mimicking metastases on 18F-FDG PET/CT. We reviewed sites of FDB revealed by 18F-FDG PET/CT imaging to allow identification of this abnormality.

MATERIALS AND METHODS

Eleven patients (7 male, 4 female, aged 16-78 years) were evaluated after 55 MBq (0.15 mCi)/kg 18F-FDG utilizing a 16-slice multiple detector CT (MDCT) whole-body PET scanner, with LOR algorithm 3D reconstruction. One- and 2-h imaging was performed in 9 patients. Standard uptake value (SUV) for each lesion, on early and delayed imaging, was calculated. Lesions were confirmed in 6 patients by biopsy. The PET images correlated with MDCT to establish the imaging characteristics.

RESULTS

Solitary lesions were found in 4 patients, two lesions in 1 patient, and in 6 patients there were multiple bone lesions. The SUV(early) ranged from 1.23 to 9.64 with an average of 3.76 ± 2.40. The SUV(delayed) ranged from 1.76 to 11.42 with an average of 4.51 ± 3.07. The SUV(delayed) decreased or increased slightly (-31% to 5%) in 6 of our patients, and increased significantly (11% to 39%) in 3. There was a negative correlation between SUVs and age, as well as the number of affected bones.

CONCLUSIONS

In our study, FDB had wide skeletal distribution with variability of 18F-FDG uptake and CT appearance. SUV in the delayed stage was seen to either decrease or increase on dual-time 18F-FDG PET scanning. It is very important to recognize the characteristics of this skeletal dysplasia to allow differentiation from skeletal metastasis.

Fibrous dysplasia of the clivus

Fibrous dysplasia (FD) of craniofacial structures is well documented, however, its involvement of the clivus is seldom described. We report a case of clival FD in a young man who presented with headache localized to the occipital area. The radiological studies revealed a monostotic disease confined to the clivus, with typical findings of hypointensity on magnetic resonance images and ground-glass density on computed tomography. The diagnosis of FD was confirmed on pathological examination of specimens taken through transsphenoidal surgery. The patient showed reduction of symptoms and no change of residual lesion on follow-up imaging taken 2.5 years later after surgery. This study includes clinical aspect, radiographic appearance, differential diagnosis and treatment strategy of this rare skull base lesion.

F-18 FDG PET-positive fibrous dysplasia in a patient with intestinal non-Hodgkin's lymphoma

Fibrous dysplasia (FD) is a common benign bone disorder of an unclear etiology. It is known that FD can appear without an increased FDG uptake on F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). However, there are also several reports that FD showed increased FDG uptake and this mimicked malignant bone involvement on FDG-PET. Herein we describe a case of biopsy-proven FDG-PET positive FD in a patient with intestinal non-Hodgkin's lymphoma (NHL). A 45-year-old woman was diagnosed with intestinal NHL, which was removed by right hemicolectomy. After the operation, the FDG-PET/CT scan showed hypermetabolic activity in the right transverse process of the T10 vertebra. The patient then received a total of 6 cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) chemotherapy every 3 weeks. After completion of the planned chemotherapy, the 2(nd) FDG-PET/CT showed increased FDG uptake (SUVmax=6.0 g/mL) of the previous bone lesion. The MR images revealed a T1-hypointense lesion with sharp borders in the same region, and this showed homogenous contrast enhancement on the fat-suppressed T1-weighted images. After the radiologic studies were carefully reviewed, the bone lesion was assumed to be benign such as FD. We performed bone biopsy and the histological examination confirmed the diagnosis of FD. In conclusion, bone lesions with FDG uptake need to be carefully interpreted when evaluating patients with known malignancy.

Conversion of FDG PET activity of fibrous dysplasia of the skull late in life mimicking metastatic disease

Fibrous dysplasia (FD) accounts for 7% of benign bone tumors. It is a developmental disorder of unclear etiology. The lamellar cancellous bone of the medullary cavity is replaced with immature fibroosseous tissue. We describe a case of FD of the skull in a patient of advanced age (69 years) with recent diagnosis of colon cancer, which changed its FDG activity and CT appearance within 10 months of follow-up. Surgical biopsy confirmed FD. Several case reports describe FDG-avid FD, but conversion of metabolic activity late in life is probably unusual.

The appearance of Mazabraud's syndrome on 18F-FDG PET/CT

Mazabraud's syndrome is a rare disorder, the main characteristics of which are fibrous dysplasia of bone associated with intramuscular myxomas. The metabolic characteristics of intramuscular myxomas, associated with fibrous dysplasia, have not previously been described with 18F-FDG-PET. Our case demonstrates that there is low, but not insignificant uptake associated with these intramuscular myxomas, with a standardized uptake value (SUV) range between 1.3 and 2.6. As such, this entity merits consideration when evaluating hypoattenuating intramuscular masses, particularly in the context of fibrous dysplasia.

PET-positive fibrous dysplasia--a potentially misleading incidental finding in a patient with intimal sarcoma of the pulmonary artery

Benign bone tumors can show an increased FDG uptake in FDG-PET/CT investigations. In the presented case, an incidentally detected PET-positive asymptomatic fibrous dysplasia was initially misinterpreted as a metastasis in a patient with intimal sarcoma of the pulmonary artery.

Unexpected finding of elevated glucose uptake in fibrous dysplasia mimicking malignancy: contradicting metabolism and morphology in combined PET/CT

Fibrous dysplasia is a common benign disorder of bone in which fibro-osseous tissue replaces bone spongiosa. Lesions have a typical appearance on computed tomography (CT) images and regularly show a markedly increased uptake in bone scintigraphy using (99m)Tc-labelled methylene diphosphonate ((99m)Tc-MDP) as radiotracer. The glucose avidity of these lesions depicted by positron emission tomography (PET) using the radiolabelled glucose derivative (18)F-fluoro-2-deoxy-glucose (FDG) is less well known since FDG-PET does not have a role in the assessment of this disease. However, single cases have been reported in which fibrous dysplasia was present in patients undergoing FDG-PET scanning for oncological reasons, and no significant FDG uptake was observed for lesions identified as fibrous dysplasia. We report on a 24-year-old man with known fibrous dysplasia who underwent combined FDG-PET/CT scanning because of suspected recurrence of testicular cancer. In contrast to prior reports, a markedly elevated uptake of FDG was seen in numerous locations that were identified as fibrous dysplasia by CT. Based on this result, we conclude that fibrous dysplasia may mimick malignancy in FDG-PET and that coregistered CT may help to resolve these equivocal findings.

Bone metastasis detected by FDG PET in a patient with breast cancer and fibrous dysplasia

Bone scintigraphy is sensitive for detecting bone metastases in patients with malignancies. However, it is often difficult to differentiate bone metastases from other nonmalignant lesions. We encountered a patient with a history of breast cancer who showed substantial elevation of tumor markers 4 years after surgery. Although there were no subjective symptoms and the bone scan showed multiple hot spots, which were similar to previous scans and which had been diagnosed as fibrous dysplasia on radiographs, a whole-body FDG PET scan showed a solitary area of intense uptake at the site of one of the hot spots in the bone scan. A solitary bone metastasis was confirmed by MRI and the patient then received radiation therapy and the elevated tumor markers of CEA and CA 15-3 were normalized after the therapy.

Magnetic resonance imaging and [11C]methyl-L-methionine positron emission tomography of fibrous dysplasia--two case reports

Two cases of fibrous dysplasia in the skull base bone appeared hypointense on T1- and T2-weighted magnetic resonance imaging, with accumulation of [11C]methyl-L-methionine ([11C]Met) on positron emission tomography (PET). Fibrous dysplasia is a benign bone disorder which is identified by its distinctive radiography, computed tomography, and bone scintigraphy findings. [11C]Met PET may indicate the presence of viable tumor-like cells in fibrous dysplasia.