F-18 FDG PET and PET/CT evaluation of response to chemotherapy in bone and soft tissue sarcomas

OBJECTIVE: F-18 FDG PET has been used to grade sarcomas and assess response to therapy in advanced disease. Certain chemotherapy agents are thought to induce an inflammatory response in the tumor bed that can make interpretation of post-therapy FDG PET scans difficult. A review of our experience with PET in assessing therapy response in osseous and soft tissue sarcomas (OSTS) is presented. METHODS: This is a retrospective study (January 1999 to December 2004) of 14 patients with histologic diagnosis of OSTS, who had 2 consecutive PET examinations for evaluation of chemotherapy response. The group included 8 men and 6 women, with age range of 18 to 56 years (average, 36 +/- 14). Semiquantitative assessment of FDG uptake was performed by calculating maximum standard uptake value (SUVmax) before and after treatment. The response to therapy was assessed independently by tumor necrosis at post-therapy surgery and according to European Organization for Research and Treatment of Cancer (EORTC) criteria for PET. The follow-up PET examinations were performed at an interval of 28 to 166 days (average, 90 +/- 45). All patients ended the ifosfamide regimen at 7 to 36 (average, 16 +/- 9) days before the follow-up PET scans. Five of them received methotrexate, adriamycin, and/or cisplatin as well. RESULTS: Based on the EORTC criteria alone, 3 patients (21.4%) had progression of disease (increase in SUVmax of 29%-69%; mean, 48% +/- 20%), 5 patients (35.7%) had stable disease, and 6 patients (42.8%) had partial response (decrease in SUVmax of 27%-84%; mean, 62% +/- 23%). Across all patients, the tumor necrosis postchemotherapy ranged from 5% to 100% (mean, 64% +/- 34%). In 8 patients (57.1%) the tumor necrosis correlated with the SUVmax changes. However, for 3 patients, the SUVmax changes indicated partial response despite necrosis of fewer than 90% of the surgical specimens, whereas 3 patients with >90% tumor necrosis had SUVmax changes indicative of stable disease. CONCLUSION: The pathologically determined degree of necrosis postneoadjuvant chemotherapy was concordant with PET-assessed EORTC classification of response in 57.1% of the cases. However, a significant number of patients had discrepancies, which may be in part explained by chemotherapy-induced inflammation. The latter should be considered during post-therapy PET interpretation in OSTS.     

The appearance of osseous PEComa on F-18 FDG PET/CT

A 29-year-old male presented with a 6-month history of left hip pain. Radiography and CT demonstrated a 6-cm lytic lesion of the left acetabulum. F-18 FDG PET for staging of the biopsy-proven malignant PEComa demonstrated intense hypermetabolism corresponding to the lytic left acetabulum. The patient underwent left hemipelvectomy with reconstructive surgery. On a follow-up F-18 FDG PET scan 3 months after initial surgery, a left lung pleural-based 9-mm nodule with hypermetabolism (SUVmax 4.1) was discovered and pathologically proven to be metastases from the primary osseous PEComa.     

FDG PET/CT imaging in primary osseous and soft tissue sarcomas: a retrospective review of 212 cases

Purpose  

The aims of this study are to evaluate the sensitivity of FDG PET/CT for detection of soft tissue and osseous sarcomas on the basis of FDG avidity.     

F-18 FDG PET/CT staging of multiple myeloma with diffuse osseous and extramedullary lesions

Multiple myeloma is the most common plasma cell neoplasm, with abnormal clonal proliferation of B cells in bone marrow. Its staging is important for therapeutic management and prognosis. F-18 FDG PET/CT is of proven value in staging and posttherapeutic monitoring multiple myeloma. Through imaging integration, PET provides functional detection of high metabolic lesions whereas CT provides correlated anatomic localization. The authors present a case of multiple myeloma status post chemotherapy and stem cell transplant with diffuse osseous and extramedullary lesions evaluated by PET/CT. The extramedullary involvement concerns the maxillary sinus, thyroid cartilage, mediastinum, retroperitoneum, neuroforamen, and epidura.     

F-18 FDG PET/CT in relapsing polychondritis

We report a case of relapsing polychondritis for which fluorodeoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT) showed increased FDG accumulation in all rib cartilages, as well as in the larynx, trachea, and major bronchi. Contrast-enhanced CT during PET/CT showed smooth tracheal and bronchial wall thickening with calcification and airway narrowing. After steroid therapy, clinical symptoms and laboratory data were improved and cartilaginous FDG accumulation had completely disappeared. FDG PET/CT is considered to be a powerful radiological tool to assess the disease activity of relapsing polychondritis.     

Collision lung cancer on F-18 FDG PET/CT

We report a case of a primary collision lung cancer consisting of squamous cell carcinoma and adenocarcinoma. A 73-year-old man with an abnormality found on chest radiograph in the right lower lobe was examined by FDG PET/CT (F-18 fluorodeoxyglucose positron emission tomography/computed tomography). The tumor was composed of 2 different morphologic and FDG accumulation portions and a collision tumor was suspected. Histopathologically, this tumor was composed of squamous cell carcinoma and adenocarcinoma. Each element was clearly distinguished but touched. FDG PET/CT is a useful tool to diagnose collision tumor as it shows morphologic and metabolic differences between 2 distinct tumor components.     

Palpation thyroiditis seen on F-18 FDG PET/CT

A 29-year-old woman presented with a new right supraclavicular mass on a background of resection of a malignant melanoma from her right shoulder before 4 years. F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging revealed uptake in a right supraclavicular node and the inferior pole of the left lobe of the thyroid gland. Subsequent resection and histology of the right supraclavicular node and the left lobe of the thyroid gland demonstrated metastatic melanoma and palpation thyroiditis, respectively. A number of malignant and benign pathologies of the thyroid demonstrate FDG uptake, with 75% being benign. To our knowledge, the findings of palpation thyroiditis on FDG PET/CT have never been previously described.     

Uterine Epithelioid Angiosarcoma on F-18 FDG PET/CT

Uterine epithelioid angiosarcoma can have conventional imaging characteristics similar to those of other uterine tumors, such as leiomyoma, leiomyosarcomas or hemangioendothelioma. Uterine epithelioid angiosarcoma exhibiting increased fluorine-18 fluorodeoxyglucose (F-18 FDG) activity can be misdiagnosed. A 61-year-old woman who was diagnosed with uterine epithelioid angiosarcoma underwent F-18 FDG positron emission tomography/computed tomography (PET/CT) as a part of the pretreatment work up for surgery. F-18 FDG PET/CT showed an intense F-18 FDG uptake in the uterus in addition to increased F-18 FDG uptake at the paraaortic and aortocaval lymph nodes. To our knowledge, this is the first case report of intense F-18 FDG uptake in uterine epithelioid angiosarcoma in Korea.     

Peritoneal Lymphomatosis Imaged by F-18 FDG PET/CT

Peritoneal lymphomatosis is uncommon, but when encountered is associated with aggressive histological subtypes of high-grade lymphoma, such as small-cell, large-cell, mixed large and small cell, non-cleaved, lymphoblastic Burkitt-like, and diffuse large B cell lymphomas. The CT findings of peritoneal lymphomatosis are linear or nodular peritoneal thickening, retroperitoneal lymphadenopathy, omental and mesenteric involvement with streak-like infiltrations or a bulky mass, bowel wall thickening, hepatosplenomegaly, and ascites. The authors report the first FDG PET/CT images of diffuse large B-cell lymphoma of small bowel origin associated with peritoneal lymphomatosis in a 69-year-old man. The lesions demonstrated intense FDG uptake in PET/CT images.     

F-18 FDG PET/CT evaluation of radiotherapy response in rare case of mucosa-associated lymphoid tissue lymphoma

We experienced two cases of mucosa-associated lymphoid tissue (MALT) lymphoma arising at unusual locations and used F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) to evaluate their response to radiation therapy (RT). A 62-year-old male with proven prostatic MALT lymphoma and a 43-year-old woman with proven duodenal MALT lymphoma had diffuse FDG uptake in the lesion. Both cases were treated with RT; following FDG, PET/CT showed decreased FDG uptake in each lesion. Neither patient had evidence of recurrence at more than 18 months after RT. FDG PET/CT is useful for indicating the treatment site in MALT lymphoma and in evaluation of therapeutic response following RT.     

Dual-time-point F-18 FDG PET/CT for evaluation in patients with malignant lymphoma

Objective

The aim of this study was to evaluate the usefulness of F-18 fluorodeoxyglucose (FDG) dual-time-point (DTP) positron emission tomography (PET)/computed tomography (CT) with semiquantitative analyses for the initial staging in patients with malignant lymphoma.

Methods

Forty-three patients had DTP PET/CT, with 60-min and 2-h scan [n?=?8, Hodgkin??s lymphoma (HL); n?=?12, indolent non-Hodgkin lymphoma (NHL); n?=?23, aggressive NHL].

Results

A total of 524 lesions were evaluated (406 lymph nodes and 118 extra-nodal lesions). The maximum standardized uptake value (SUV_max) on 2-h delayed scan (SUV₂) was significantly higher than those on 1-h early scan (SUV₁) for all groups (P?<?0.0001 for HL; P?<?0.0001 for indolent NHL; P?<?0.0001 for aggressive NHL). Significant differences were detected between HL and indolent NHL, between indolent NHL and the aggressive NHL for both SUV₁ and SUV₂ (each P?<?0.0001). No significant differences were detected between HL and aggressive NHL for both SUV₁ and SUV₂ (P?=?0.6891 for SUV₁; P?=?0.8828 for SUV₂); however, significant differences were detected for the retention index of SUV_max between these groups (P?=?0.0238).

Conclusions

DTP F-18 FDG PET/CT with a semiquantitative technique may have the potential to provide the more accurate diagnoses for the staging of malignant lymphoma and the more important role in predicting the histological grades of malignancy compared with single-time-point F-18 FDG-PET scan.