Heterogeneous FDG Uptake Research Articles

Case Report: A rare case of multicentric angiosarcomas of bone mimicking multiple myeloma on 18F-FDG PET/CT

BackgroundAngiosarcoma, a rare endothelial-origin tumor, can develop throughout the body, with the head and neck skin being the most commonly affected areas. It can also originate in other sites such as the breast, iliac artery, and visceral organs including the liver, spleen, and kidneys. Angiosarcoma of the bone is remarkably rare, presenting as either unifocal or multifocal bone lesions and often leading to a grim prognosis. Diagnosing bone angiosarcoma poses a significant challenge. 18F-FDG PET/CT serves as a reliable and indispensable imaging modality for evaluating distant metastases and clinically staging angiosarcomas.Case reportA 57-year-old woman presented with a 10-day history of dizziness and headaches. Cranial CT scan revealed bone destruction of the parietal bone, accompanied by soft tissue lesions, protruding into the epidural space. MRI examination demonstrated lesions with slightly elevated signal intensity on T2FLAIR, showing moderate enhancement. Furthermore, multiple foci were observed within the T12, L1-5, and S1-2 vertebrae, as well as in the bilateral iliac bones. For staging, 18F-FDG PET/CT was performed. The MIP PET showed multifocal FDG-avid lesions in the sternum, bilateral clavicles, bilateral scapulae, multiple ribs, and pelvic bones. Heterogeneous FDG uptake was observed in multiple bone lesions, including intracranial (SUVmax = 11.3), right transverse process of the T10 vertebra (SUVmax = 5.8), ilium (SUVmax = 3.3), and pubis (SUVmax = 4.7). The patient underwent surgical resection of the cranial lesion. The pathological diagnosis was made with a highly differentiated angiosarcoma.ConclusionAngiosarcoma of bone on FDG PET/CT scans is characterized by abnormal FDG uptake along with osteolytic destruction. This case highlights that angiosarcoma of bone can manifest as multicentric FDG uptake, resembling the pattern seen in multiple myeloma. FDG PET/CT can be a useful tool for staging this rare malignant tumor, offering the potential to guide biopsy procedures toward the most metabolically active site. And it should be considered in the differential diagnosis of multiple osteolytic lesions, including metastatic carcinoma, multiple myeloma, and lymphoma of bone.

Abstract 17111: Spontaneous Regression of Cardiac Angiosarcoma in a 17-Year-Old Male

Description of Case: A fit and healthy 17-year-old male was admitted with a 10-day history of chest pain and SOB. He was taking no medication and had no significant past medical or family history. Clinical examination revealed signs of pericarditis with widespread ST elevation and PR depression on ECG. TTE showed a moderate, global pericardial effusion. He was treated for pericarditis with anti-inflammatory medication and discharged with follow up a few weeks later. Repeat TTE demonstrated a mass in the pericardial space adjacent to the RV free wall. Urgent CMR was requested to exclude malignancy and showed a large, irregular heterogenous mass adjacent to the RA and RV with invasion into the RV free wall. CMR characterisation including first pass perfusion was indeterminate. CT TAP showed no distant metastases. Percutaneous biopsy was non diagnostic and serial CMR 3 weeks later showed significant reduction of the mass. PET-CT confirmed reduction in the size of the mass although there was moderate heterogeneous FDG uptake, more suggestive of malignancy rather than a benign lesion. Given the apparent resorption of the mass, repeat CMR was planned 3 months later. Repeat CMR (6 months after initial CMR) showed significant increase in the size of the cardiac mass. Surgical biopsy confirmed cardiac angiosarcoma and was unresectable. After MDT discussion, the patient was started on doxorubicin, dexrazoxane and pazopanib. This has failed to control the tumour, and he has now commenced a trial of paclitaxel. Discussion: Spontaneous regression of cardiac rhabdomyoma in infants has been described, but this does not extend to other primary cardiac tumours or adults. The re-emergence and significant increase in size of the mass suggests initial regression may have been a percutaneous biopsy effect causing collapse or resorption of the necrotic core. Suggested mechanisms include disruption of the tumour feeding artery during biopsy or activation of the immune system.

PSAT288 Mucosa-associated Lymphoid Tissue Thyroid Lymphoma Presenting as a Rapidly Growing Neck Mass in an Asymptomatic Male Patient

Abstract A 77-year-old male was referred to endocrinology for a 2-month history of a rapidly enlarging painless left neck mass. His only other complaint was unintentional weight loss of 10 pounds over 12-months. On exam patient had a firm, smooth, nontender 2 cm thyroid/neck mass extending below left clavicle. No abnormalities were detected for right thyroid gland. There was no palpable lymphadenopathies or hepatosplenomegaly noted. No signs of tracheal, esophageal, or neck vein compression were noted. He did not have any history of radiation exposure, family history of thyroid-related disorders, or malignancy. Laboratory test including complete blood count, comprehensive metabolic profile and TSH were within normal limits. TPO antibody was positive. Ultrasound revealed a 7.7×4.1×4 cm hypoechoic spongiform mass replacing the left lobe of the thyroid, as well as scattered sub centimeter nodules. Contrasted CT of the neck confirmed 6.5×5.2×3.9 cm left thyroid mass causing mild rightward deviation of the trachea and extending into the superior mediastinum and no lymphadenopathy. FNA of the mass revealed presence of crushed lymphoid cells without thyroid follicular cells, which raised the possibility of chronic lymphocytic thyroiditis. FDG- PET scan showed intense, heterogeneous FDG uptake in the left neck mass (max SUV=10.7), likely arising from the left thyroid lobe concerning for thyroid malignancy without evidence of distant metastases. The patient underwent a left thyroid nodule core biopsy with subsequent left thyroid hemithyroidectomy. The pathology stains of the excised left thyroid lobe core biopsy showed extra nodal zone lymphoma of mucosa- associated lymphoid tissue (MALT Lymphoma) with extensive plasmocytic differentiation. Surgical path confirmed extra nodal zone lymphoma of mucosa-associated lymphoid tissue (MALT Lymphoma) with extensive plasmocytic differentiation and foci of chronic lymphocytic thyroiditis. Immunochemistry studies supported a diagnosis of plasma cell neoplasm or the plasma cell component of a B-cell lymphoproliferative disorder. Short-term follow-up FDG-PET and CT imaging demonstrated post-surgical changes without evidence of recurrence. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

Thyroid Tuberculosis Causing Fever of Unknown Origin in a Patient With Multinodular Goiter

Introduction: Tuberculosis (TB) involving the thyroid gland is rare and typically results in hypothyroidism. Here we report a case of thyroid TB that presented with hyperthyroidism. Clinical Case: A 54-year-old woman with a history of hyperthyroidism due to toxic multinodular goiter presented to the emergency department with fever of unknown origin associated with sore throat, non-productive cough, night sweats, diarrhea, and right anterior neck pain that worsened with coughing. Her fevers were intermittent, ranging from 38 to 39 degrees Celsius, and would subside with acetaminophen. She reported that her symptoms had started after getting a thyroid [Tc-99m] pertechnetate scan and 24 hour [I-131] sodium iodide uptake study a month prior. The scan at the time revealed hyperfunctioning thyroid nodules in the lower lobes bilaterally. The 24-hour uptake was 20.2% which is within the normal range of 7 to 30%. TSH on presentation was 0.01 mIU/L (Normal range 0.3-5.50 mIU/L), free T4 was 2.05 ng/dL (Normal range 0.76 -1.7 ng/dL), and free T3 was 5 pg/mL (Normal range 1.9-3.9 pg/mL). Exam revealed a multinodular goiter, which was firm with mild tenderness, and no cervical lymphadenopathy. Infectious workup was unremarkable other than a positive interferon-gamma release assay. As for TB risk factors, the patient immigrated to the United States from Albania about 13 years prior. The patient denied any known TB exposure, neither had she been treated for TB. Radiograph and computed tomography (CT) of the thorax were unremarkable other than re-demonstration of the multinodular goiter. Fluorodeoxyglucose-18 positron emission tomography (FDG-PET), which was performed to identify any focus of active TB, had revealed intense, infiltrative, heterogeneous FDG uptake of the nodular thyroid gland with reactive level 3 and 4 cervical lymph nodes. Also, the scan revealed hyper-metabolic hilar, pre-tracheal, and sub-carinal lymph nodes which could represent latent TB. Further workup for any other foci of active TB including broncho-alveolar lavage, sputum cultures, lumbar puncture, and bone marrow biopsy were unremarkable. Thyroid ultrasound revealed 2 right sided and 3 left sided thyroid nodules, mostly solid and hypoechoic. Fine needle aspiration of nodules revealed benign follicular nodules bilaterally, however the left aspirate contained loose aggregates of histiocytes consistent with non-necrotizing granulomas. Acid-fast bacilli stain of the aspirate was negative. The patient was started on therapy for active TB with isoniazid, rifampin, pyrazinamide, and ethambutol. Six weeks after treatment her fevers had resolved. Conclusion: Thyroid TB should be considered when the severity of symptoms cannot be explained by the degree of hyperthyroidism alone in patients with increased risk of TB. Additionally, TB in the thyroid can be challenging to identify in a patient with known underlying thyroid disease.

Chordoma: 18F-FDG PET/CT and MRI imaging features.

Examine the 18F-FDG PET/CT and MRI imaging characteristics of chordoma. Biopsy-proven chordoma with a pre-therapy 18F-FDG PET/CT from 2001 through 2019 in patients > 18years old were retrospectively reviewed. Multiple PET/CT and MRI imaging parameters were assessed. A total of 23 chordoma patients were included (16 M, 7 F; average age of 60.1 ± 13.0years) with comparative MRI available in 22 cases. This included 13 sacrococcygeal, 9 mobile spine, and one clival lesions. On 18F-FDG PET/CT, chordomas demonstrated an average SUVmax of 5.8±3.7, average metabolic tumor volume (MTV) of 160.2±263.8cm3, and average total lesion glycolysis (TLG) of 542.6±1210g. All demonstrated heterogeneous FDG activity. On MRI, chordomas were predominantly T2 hyperintense (22/22) and T1 isointense (18/22), contained small foci of T1 hyperintensity (17/22), and demonstrated heterogeneous enhancement (14/20). There were no statistically significant associations found between 18F-FDG PET/CT and MRI imaging features. There was no relationship of SUVmax (p = 0.53), MTV (p = 0.47), TLG (p = 0.48), maximal dimension (p = 0.92), or volume (p = 0.45) to the development of recurrent or metastatic disease which occurred in 6/22 patients over a mean follow-up duration of 4.1±2.0years. On 18F-FDG PET/CT imaging, chordomas demonstrate moderate, heterogeneous FDG uptake. Predominant T2 hyperintensity and small foci of internal increased T1 signal are common on MRI. The inherent FDG avidity of chordomas suggests that 18F-FDG PET/CT may be a useful modality for staging, evaluating treatment response, and assessing for recurrent or metastatic disease.

FDG PET/CT and MRI Features of Pathologically Proven Schwannomas.

The aim of this study was to examine the MRI and FDG PET/CT imaging features of pathologically proven schwannomas. This institutional review board-approved retrospective study examined biopsy-proven schwannomas that underwent FDG PET/CT and/or MRI at our institution between January 1, 2002, and April 1, 2018. PET/CT features analyzed included SUVmax, metabolic ratios, volumetric metabolic measures, presence of calcification, and pattern of FDG activity. MRI features included T1/T2 signal, enhancement pattern, margins, perilesional edema, presence of muscular denervation, and size. Ninety-five biopsy-proven schwannomas were identified (40 with both PET and MRI, 35 with PET only, and 20 with MRI only), 46 females and 49 males, average age of 57.7 ± 15.3 years. The average largest dimension was 4.6 ± 2.7 cm, the average SUVmax was 5.4 ± 2.7, and lesion SUVmax/liver SUVmean was 2.2 ± 1.2. Eleven (15%) of 75 lesions had SUVmax greater than 8.1, 26/75 (35%) had SUVmax greater than 6.1, and 14/75 (19%) had lesion SUVmax/liver SUVmean greater than 3.0. On MRI, 29/53 (55%) demonstrated internal nonenhancing areas. Twenty-eight (70%) of 40 lesions with both MRI and PET demonstrated at least 1 imaging feature concerning for malignant peripheral nerve sheath tumor (irregular margins, internal nonenhancement, perilesional edema, heterogeneous FDG uptake, or SUVmax >8.1). Lesions with heterogeneous FDG activity had higher SUVmax (6.5 ± 0.5 vs 4.7 ± 0.4, P = 0.0031) and more frequent internal nonenhancement on MRI (P = 0.0218). Schwannomas may be large, be intensely FDG avid, and demonstrate significant heterogeneity, features typically associated with malignant peripheral nerve sheath tumors. A significant proportion exhibit FDG activity above cutoff levels previously thought useful in differentiating malignant from benign peripheral nerve sheath tumors.

Can PET-CT predict diagnostic success in ultrasonography-guided transthoracic fine needle aspiration biopsies in lung cancers?

ObjectiveTo examine any correlations between tumor maximum standard uptake values (SUVmax) in positron emission tomography-computed tomography (PET-CT) and homogeneous/heterogeneous tumor FDG uptake in PET-CT, and the diagnostic success of the procedure in thoracic ultrasonography (US)-guided transthoracic fine needle aspiration biopsy (TFNAB). MethodsThe files of patients who underwent thoracic US-guided TFNAB between 2013 and 2018 were examined. Patients who underwent thoracic US-guided TFNAB and were diagnosed as having primary lung cancer were considered as the US-TFNAB diagnostic group. Patients whose disease was diagnosed as primary lung cancer using a different diagnostic method (e.g. CT-guided biopsies, fiberoptic bronchoscopy) due to a lack of diagnosis despite undergoing thoracic US-guided TFNAB were allocated to the US-TFNAB non-diagnostic group. The clinical and radiologic characteristics and PET-CT parameters of the two groups were compared. ResultsA total of 104 patients were included in the study; 79 (76%) patients whose disease was diagnosed using US-guided TFNAB, and 25 (24%) patients whose primary lung cancer could not be diagnosed with US-guided TFNAB. The mean SUVmax value of the US-TFNAB diagnostic group was 19.5 ± 10.1, whereas it was 15.1 ± 8.9 in the US-TFNAB non-diagnostic group (p = 0.016). Whether a lesion showed homogeneous or heterogeneous FDG uptake did not effect diagnostic success (p = 0.289). SUVmax value was the only effective independent factor in the diagnostic success of the procedure (p = 0.035). ConclusionsHigh SUVmax values in PET-CT in lung cancers may increase the diagnostic success of US guided-TFNAB procedures.

1174Characterization of disease hot-phases using 18f-fluorodeoxyglucose positron emission tomography in arrhythmogenic cardiomyopathy caused by desmosomal gene mutations

Abstract Introduction Mutations in the genes encoding for desmosomal proteins are associated with Arrhythmogenic Cardiomyopathy (AC), a condition in which “hot-phases” reminiscent of myocarditis can develop and which represent active disease progression. Detection of hot-phase disease can offer novel treatment opportunities. Purpose We used 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) to determine the prevalence of myocardial inflammation during clinical hot phases in AC. Methods Nineteen (12 male; age 38±14 years) symptomatic desmosomal gene mutation carriers (PKP-2, n=6; DSG-2, n=3; DSC-2, n=1; DSP, n=9) underwent FDG-PET and cardiac magnetic resonance (CMR). AC was diagnosed according to the 2010 Task Force diagnostic criteria. The indication for FDG-PET was presentation with clinically suspected myocarditis in 10 (53%), increase in arrhythmic burden in 4 (21%), deteriorating left ventricular (LV) systolic function in 3 (16%) and as part of a diagnostic workup in 2. We compared regional distribution of FDG uptake and late gadolinium enhancement (LGE) on CMR using a standard 16-segment model. Concordance between the two tests was defined as >50% of segment overlap and partial concordance as 1- 50%. Cohen's κ was used to evaluate the inter-method agreement between FDG and LGE. Results Nine (47%) patients (5 male) had LV heterogeneous FDG uptake. RV uptake was never observed. Eight of these cases had a definite and 1 had a borderline diagnosis of AC. FDG uptake associated with the presence of DSP gene mutations (7/9, 78% vs 2/10, 20%, p=0.02) and older age (44±12 vs 33±15 years, p=0.05). Concurrent CMR study was available in 15 patients, including all nine with a positive FDG-PET. RV LGE was present in 6 (40%) and LV LGE in 14 cases (93%). All nine (100%) patients with FDG uptake had LV LGE. The commonest segments with FDG-uptake were the basal-anterior, mid-inferolateral and mid-anterolateral (5 cases, 56%), whereas LGE was most commonly present in the mid-anteroseptal (8 cases, 89%) followed by the basal- and mid-inferior segments (6 cases, 67%). Concordance of FDG uptake and LGE was present in 2 cases (22%). There was no concordance in 1 case (11%). Partial concordance was present in 6 (67%). There was poor inter-method topographical agreement between FDG-PET and CMR, κ = 0.04, p=0.64. Conclusion Up to 50% of desmosomal gene positive AC patients, and especially those with DSP mutations, and clinical “hot phases” have evidence for myocarditis on FDG-PET. The topographical variation between PET and CMR highlight the underlying pathophysiological stage of disease (inflammation versus scar) and suggest that the imaging modalities provide complementary information on tissue characterisation in AC. Acknowledgement/Funding Alexandros Protonotarios is funded by a BHF Clinical Research Training Fellowship no. FS/18/82/34024

Computational delineation and quantitative heterogeneity analysis of lung tumor on 18F-FDG PET for radiation dose-escalation

Quantitative measurement and analysis of tumor metabolic activities could provide a more optimal solution to personalized accurate dose painting. We collected PET images of 58 lung cancer patients, in which the tumor exhibits heterogeneous FDG uptake. We design an automated delineation and quantitative heterogeneity measurement of the lung tumor for dose-escalation. For tumor delineation, our algorithm firstly separates the tumor from its adjacent high-uptake tissues using 3D projection masks; then the tumor boundary is delineated with our stopping criterion of joint gradient and intensity affinities. For dose-escalation, tumor sub-volumes with low, moderate and high metabolic activities are extracted and measured. Based on our quantitative heterogeneity measurement, a sub-volume oriented dose-escalation plan is implemented in intensity modulated radiation therapy (IMRT) planning system. With respect to manual tumor delineations by two radiation oncologists, the paired t-test demonstrated our model outperformed the other computational methods in comparison (p < 0.05) and reduced the variability between inter-observers. Compared to standard uniform dose prescription, the dosimetry results demonstrated that the dose-escalation plan statistically boosted the dose delivered to high metabolic tumor sub-volumes (p < 0.05). Meanwhile, the doses received by organs-at-risk (OAR) including the heart, ipsilateral lung and contralateral lung were not statistically different (p > 0.05).

Adaptive region-growing with maximum curvature strategy for tumor segmentation in 18F-FDG PET

Accurate tumor segmentation in PET is crucial in many oncology applications. We developed an adaptive region-growing (ARG) algorithm with a maximum curvature strategy (ARG_MC) for tumor segmentation in PET. The ARG_MC repeatedly applied a confidence connected region-growing algorithm with increasing relaxing factor f. The optimal relaxing factor (ORF) was then determined at the transition point on the f-volume curve, where the volume just grew from the tumor into the surrounding normal tissues. The ARG_MC along with five widely used algorithms were tested on a phantom with 6 spheres at different signal to background ratios and on two clinic datasets including 20 patients with esophageal cancer and 11 patients with non-Hodgkin lymphoma (NHL). The ARG_MC did not require any phantom calibration or any a priori knowledge of the tumor or PET scanner. The identified ORF varied with tumor types (mean ORF = 9.61, 3.78 and 2.55 respectively for the phantom, esophageal cancer, and NHL datasets), and varied from one tumor to another. For the phantom, the ARG_MC ranked the second in segmentation accuracy with an average Dice similarity index (DSI) of 0.86, only slightly worse than Daisne’s adaptive thresholding method (DSI = 0.87), which required phantom calibration. For both the esophageal cancer dataset and the NHL dataset, the ARG_MC had the highest accuracy with an average DSI of 0.87 and 0.84, respectively. The ARG_MC was robust to parameter settings and region of interest selection, and it did not depend on scanners, imaging protocols, or tumor types. Furthermore, the ARG_MC made no assumption about the tumor size or tumor uptake distribution, making it suitable for segmenting tumors with heterogeneous FDG uptake. In conclusion, the ARG_MC was accurate, robust and easy to use, it provides a highly potential tool for PET tumor segmentation in clinic.

Positron emission tomography/computer tomography in gastrointestinal malignancies: current potential and challenges

The use of 18F-Fluoro-D-deoxy-glucose -positron emission tomography/computed tomography (FDG-PET/CT) in gastrointestinal (GI)-malignancies may not be as straightforward as in many other cancers, but the potential is clearly there in select clinical settings. The challenges include the relative non-specificity of FDG, the variable degrees of physiologic FDG-uptake, and the heterogeneous FDG-uptake in different cell types within the GI-domain, which all together hamper the use in primary diagnostics. In general, the literature is older, heterogeneous, and based on stand-alone PET, which is now largely considered obsolete. There is emerging evidence for use of hybrid PET/CT, but the literature is still relatively sparse. The main indications are preoperative staging of distant metastases, not only in limited disease but also before curative treatment of limited metastatic disease. Controversies remain concerning liver metastases but improved technology boast well for the future role of FDG-PET/CT not least concerning equivocal findings on conventional imaging. In our opinion, an important upcoming indication is early response assessment, perhaps mostly in the neoadjuvant settings of upper GI-malignancies, but standardization of response assessment criteria is lacking before a more widespread implementation is feasible. Finally, there seems to be a significant role in recurrence detection, especially in CRC.

Serial FDG-PET scans help to identify steroid resistance in cardiac sarcoidosis

BackgroundCardiac sarcoidosis (CS) is increasingly being recognized. Immunosuppression with corticosteroids is the mainstay of therapy. But the optimal dose of steroids and how to assess response to therapy is not known. Prognosis is poor if these patients are untreated or undertreated. Fluorine-18-flurodeoxyglucose positron emission computed tomography (18FDG-PET CT) is a sensitive tool in diagnosing CS. It correlates closely with the level of granulomatous inflammation and can be used to monitor response to therapy. MethodsWe identified 15 patients (6 women; mean age, 42.9±12.5years) based on histopathological diagnosis. All had a baseline and follow-up fasting 18FDG-PET CT scans before and after steroid therapy. Non-responders were defined as those in whom ventricular arrhythmias, symptoms of HF and left ventricular systolic function and/or ventricular arrhythmias did not improve or worsened despite steroid therapy. FDG uptake of involved myocardium and lymph nodes (LN) was compared in clinical responders and non-responders on follow-up. ResultsOf the 15 patients, 4 were clinical non-responders to steroid therapy. Follow-up 18FDG-PET CT was performed at 125.8±54.2days after the initiation of steroid therapy. Myocardial maximum standardized uptake of FDG (SUVmax) value decreased significantly in responders (p=0.004) while there was an increase in non-responders (p<0.05) on follow-up. Number of left ventricle (LV) segments with FDG uptake significantly decreased in responders (p=0.007), and on increasing trend in non-responders (p=0.465). Heterogeneous FDG uptake on baseline PET scan, increase in intensity as well as area of myocardial inflammation on follow-up PET scan was associated with poor clinical outcome despite steroid therapy. ConclusionsSerial 18FDG-PET CT scans can be used to monitor steroid therapy in active CS. Increase in PET uptake after steroid therapy correlates with poor clinical outcome. Repeat PET scan may help to predict steroid-resistant CS and the need for up-titration of immunosuppressive therapy among poor responders to initial therapy.

Intrathoracic Desmoid Tumor

A 47-year-old female was referred to the hospital because of persistent pain at the ventral right side of the chest for several weeks. Except for ankylosing spondylitis, her medical history was insignificant. The patient doesn’t smoke and there is no history of thoracic trauma or surgery. There were no alarm symptoms. Clinical examination revealed no abnormalities and routine hematologic and biochemical evaluation were normal. Breast US was performed and incidentally a sharply delineated heterogeneous intra-thoracic soft tissue mass of 4.5 × 9 cm was observed arising from the right chest wall. Additional X-rays of the chest showed a large intra-thoracic right-sided mass with a broad pleural base, smoothly bordering the lung parenchyma (Fig. A). Contrast-enhanced CT of the chest confirmed the presence of a right-sided sharply delineated heterogeneous intra-thoracic mass with a broad pleural base (Fig. B). Bony alterations were present on the adjacent ribs. There were no enlarged lymph nodes, pleural fluid or intrathoracic nodules. At MRI imaging, the mass had mixed signal intensity on T2WI and was iso-intense to skeletal muscle on axial 3D gradient-echo T1WI images. The lesion was irregularly marginated where it bordered the thoracic wall, suggesting growth in the intercostal spaces. Strong and heterogeneous enhancement occurred on T1WI after gadolinium administration (Fig. C). Finally PET-CT showed only mild, heterogeneous FDG-uptake in the mass, suggesting a benign lesion. Because malignancy could still not be ruled out, a surgical biopsy was performed. Pathologic examination showed a fibromatous spindle cell lesion without signs of high grade malignancy. No mitosis, nor necrosis nor pleomorphism were observed. Histological and immunohistochemical image was strongly suggestive for desmoid tumor with staining negative for keratin, CD34 and S100 and positive for beta-catenin and actin. These results were re-examined and confirmed in a second hospital. Surgery was recommended, but the patient rejected and chose radiotherapy. Follow-up imaging six months later showed slight volume loss of the tumor. The patient remains in further follow-up.

Primary lung tumor segmentation from PET-CT volumes with spatial-topological constraint.

Accurate lung tumor segmentation is a prerequisite for effective radiation therapy and surgical planning. However, tumor delineation is challenging when the tumor boundaries are indistinct on PET or CT. To address this problem, we developed a segmentation method to improve the delineation of primary lung tumors from PET-CT images. We formulated the segmentation problem as a label information propagation process in an iterative manner. Our model incorporates spatial-topological information from PET and local intensity changes from CT. The topological information of the regions was extracted based on the metabolic activity of different tissues. The spatial-topological information moderates the amount of label information that a pixel receives: The label information attenuates as the spatial distance increases and when crossing different topological regions. Thus, the spatial-topological constraint assists accurate tumor delineation and separation. The label information propagation and transition model are solved under a random walk framework. Our method achieved an average DSC of 0.848 ± 0.036 and HD (mm) of 8.652 ± 4.532 on 40 patients with lung cancer. The t test showed a significant improvement (p value < 0.05) in segmentation accuracy when compared to eight other methods. Our method was better able to delineate tumors that had heterogeneous FDG uptake and which abutted adjacent structures that had similar densities. Our method, using a spatial-topological constraint, provided better lung tumor delineation, in particular, when the tumor involved or abutted the chest wall and the mediastinum.

Topology polymorphism graph for lung tumor segmentation in PET-CT images

Accurate lung tumor segmentation is problematic when the tumor boundary or edge, which reflects the advancing edge of the tumor, is difficult to discern on chest CT or PET. We propose a ‘topo-poly’ graph model to improve identification of the tumor extent. Our model incorporates an intensity graph and a topology graph. The intensity graph provides the joint PET-CT foreground similarity to differentiate the tumor from surrounding tissues. The topology graph is defined on the basis of contour tree to reflect the inclusion and exclusion relationship of regions. By taking into account different topology relations, the edges in our model exhibit topological polymorphism. These polymorphic edges in turn affect the energy cost when crossing different topology regions under a random walk framework, and hence contribute to appropriate tumor delineation. We validated our method on 40 patients with non-small cell lung cancer where the tumors were manually delineated by a clinical expert. The studies were separated into an ‘isolated’ group (n = 20) where the lung tumor was located in the lung parenchyma and away from associated structures / tissues in the thorax and a ‘complex’ group (n = 20) where the tumor abutted / involved a variety of adjacent structures and had heterogeneous FDG uptake. The methods were validated using Dice’s similarity coefficient (DSC) to measure the spatial volume overlap and Hausdorff distance (HD) to compare shape similarity calculated as the maximum surface distance between the segmentation results and the manual delineations. Our method achieved an average DSC of 0.881 ± 0.046 and HD of 5.311 ± 3.022 mm for the isolated cases and DSC of 0.870 ± 0.038 and HD of 9.370 ± 3.169 mm for the complex cases. Student’s t-test showed that our model outperformed the other methods (p-values <0.05).

F-18 FDG PET/CT findings of metastatic ovarian tumors from gastrointestinal tract origin.

To review the F-18 FDG PET/CT findings of metastatic ovarian tumors and to determine any correlation between FDG uptake by metastatic ovarian tumors and that by the primary tumors. PET/CT performed from June 2005 to March 2011 on patients with metastatic ovarian tumors of gastrointestinal tract origin malignancies was analyzed retrospectively. The SUV(max) of metastatic ovarian tumors and primary tumors, when available, was measured. Thirty-two patients were included. Of the 32 cases, 20 had metastatic tumors in bilateral ovaries and 12 had in a single ovary. The mean SUV(max) of the 52 total lesions was 4.1 ± 3.1 (range 1.2-13.3), and 46 lesions showed a heterogeneous FDG uptake pattern. In 22 cases with available primary tumor SUV(max) values, there was a moderate positive correlation with the SUV(max) of the corresponding metastatic tumors (r = 0.559, p = 0.007). There was no significant correlation between the size and SUV(max) of metastatic ovarian tumors (p = 0.128). The mean SUV(max) of metastatic ovarian tumors from colorectal cancers was significantly higher than that of stomach cancers (p = 0.039). Metastatic ovarian tumors showed FDG uptake of variable intensity, depending on the primary tumor type. The FDG uptake pattern was heterogeneous by PET imaging in vast majority of the cases. When the primary tumor demonstrates a low FDG uptake, careful evaluation is necessary since the metastatic ovarian tumors may also show low FDG uptake.

First experience of simultaneous PET/MRI for the early detection of cardiac involvement in patients with Anderson-Fabry disease.

Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder associated with severe multiorgan dysfunction and premature death. Early diagnosis and treatment strategies play a key role in patient outcome. We investigated the potential role of hybrid PET/MR imaging in the assessment of early cardiac involvement in AFD patients. Thirteen AFD patients without cardiac symptoms and with normal left ventricular function underwent simultaneous cardiac PET/MR imaging after administration of (18)F-FDG. Cardiac FDG uptake was quantified by measuring the standardized uptake value in 17 myocardial segments in each subject. The coefficient of variation (COV, i.e. the standard deviation divided by the average) of the uptake of the 17 segments was calculated as an index of heterogeneity in the heart. Six patients exhibited focal late gadolinium enhancement (LGE) indicating intramyocardial fibrosis, and four of these also had positive short inversion time inversion recovery (STIR) sequences. All patients with LGE and positive STIR MR images showed focal FDG uptake in the corresponding myocardial segments indicating inflammation. Of the seven patients with negative LGE and STIR images, five showed homogeneous FDG cardiac uptake and two showed heterogeneous FDG uptake. The COV was significantly greater in patients with focal FDG uptake (0.25 ± 0.02) than in those without (0.14 ± 0.07, p < 0.01). PET/MR imaging is clinically feasible for the early detection of cardiac involvement in patients with AFD. Further studies evaluating the role of hybrid PET/MR imaging in management of the disease in larger patient populations are warranted.

Segmentation of heterogeneous or small FDG PET positive tissue based on a 3D-locally adaptive random walk algorithm

A segmentation algorithm based on the random walk (RW) method, called 3D-LARW, has been developed to delineate small tumors or tumors with a heterogeneous distribution of FDG on PET images. Based on the original algorithm of RW [1], we propose an improved approach using new parameters depending on the Euclidean distance between two adjacent voxels instead of a fixed one and integrating probability densities of labels into the system of linear equations used in the RW. These improvements were evaluated and compared with the original RW method, a thresholding with a fixed value (40% of the maximum in the lesion), an adaptive thresholding algorithm on uniform spheres filled with FDG and FLAB method, on simulated heterogeneous spheres and on clinical data (14 patients). On these three different data, 3D-LARW has shown better segmentation results than the original RW algorithm and the three other methods. As expected, these improvements are more pronounced for the segmentation of small or tumors having heterogeneous FDG uptake.

FDG uptake heterogeneity evaluated by fractal analysis improves the differential diagnosis of pulmonary nodules

PurposeThe present study aimed to determine whether fractal analysis of morphological complexity and intratumoral heterogeneity of FDG uptake can help to differentiate malignant from benign pulmonary nodules. Materials and methodsWe retrospectively analyzed data from 54 patients with suspected non-small cell lung cancer (NSCLC) who were examined by FDG PET/CT. Pathological assessments of biopsy specimens confirmed 35 and 19 nodules as NSCLC and inflammatory lesions, respectively. The morphological fractal dimension (m-FD), maximum standardized uptake value (SUVmax) and density fractal dimension (d-FD) of target nodules were calculated from CT and PET images. Fractal dimension is a quantitative index of morphological complexity and tracer uptake heterogeneity; higher values indicate increased complexity and heterogeneity. ResultsThe m-FD, SUVmax and d-FD significantly differed between malignant and benign pulmonary nodules (p<0.05). Although the diagnostic ability was better for d-FD than m-FD and SUVmax, the difference did not reach statistical significance. Tumor size correlated significantly with SUVmax (r=0.51, p<0.05), but not with either m-FD or d-FD. Furthermore, m-FD combined with either SUVmax or d-FD improved diagnostic accuracy to 92.6% and 94.4%, respectively. ConclusionThe d-FD of intratumoral heterogeneity of FDG uptake can help to differentially diagnose malignant and benign pulmonary nodules. The SUVmax and d-FD obtained from FDG-PET images provide different types of information that are equally useful for differential diagnoses. Furthermore, the morphological complexity determined by CT combined with heterogeneous FDG uptake determined by PET improved diagnostic accuracy.

Infection de prothèse vasculaire : 18TEP-FDG vs scintigraphie aux leucocytes marqués (planaires et TEMP/TDM)

Vascular prosthesis infection is an uncommon but life-threatening complication. Its diagnosis is difficult to establish especially due to the low specificity of computed tomography (CT). The aim of this preliminary study was to compare the diagnostic value of positron emission tomography with 18FDG ( 18FDG-PET) and 99mTc-HMPAO-labeled leukocytes scintigraphy in this indication. 18FDG-PET/CT and 99mTc-HMPAO-labeled leukocytes scintigraphy (planar at 6th and 24th hours after injection + SPECT/CT at the 6th hour) were prospectively performed in 11 patients (total of 22 vascular prosthesis with 14 clinical suspicions of infection). Both scans were retrospectively and blindly assessed by two independent nuclear medicine physicians. Interpretation was based on visual analysis. The gold standard was bacteriology findings or clinical follow-up greater than 6 months. Eight prostheses were considered as infected. PET found eight true-positive and one false-positive. Scintigraphy found eight true-positive and no false-positive. A focal or heterogeneous FDG-uptake higher or equal than hepatic uptake was considered as positive in PET. A focal prosthetic activity, stable or increased at the 24th hour was considered as positive in labeled leukocyte scintigraphy. SPECT/CT gave accurate anatomic localization and differentiated clearly infections of soft tissues from those of prostheses. 18FDG-PET could be performed in first-line in suspicion of vascular prosthesis infection. In litigious cases, a 99mTc-HMPAO-labeled leukocytes scintigraphy in association with SPECT/CT could bring additional arguments for infection diagnosis.