Hyo Jung Seo

Prognostic value of 18F-FDG PET for hepatocellular carcinoma patients treated with sorafenib

Background: Sorafenib (Nexavar) is an orally active multikinase inhibitor that is approved for the treatment of hepatocellular carcinoma (HCC). In this study, we used 18F‐2‐fluoro‐2‐deoxyglucose (18F‐FDG) with positron emission tomography (PET) to predict the treatment outcome of sorafenib in patients with advanced HCC.

Positron Emission Tomography/Magnetic Resonance Imaging Evaluation of Lung Cancer Current Status and Future Prospects

Various designs of positron emission tomography/magnetic resonance imaging (PET/MRI) systems have been recently introduced to clinical practice, which have overcome preexisting technical challenges concerning the fusion of PET and MRI systems. Although further improvements are still necessary especially for bony lesions, quantification using current MRI-based attenuation correction techniques has been shown to be comparable to that of PET/computed tomography (CT) systems. On the basis of the results of previous whole-body MRI studies, PET/MRI is expected to show even better performance than PET/CT in M-staging especially for brain and liver metastases. Another advantage of PET/MRI over PET/CT, in addition to good soft tissue contrast, is the potential reduction in radiation dose. The next important hurdle to overcome for its clinical application is the development of time-efficient protocols for lung cancer evaluation and interpretation of discordant results from both modalities. Multiparametric imaging through PET/MRI will help radiologists better understand tumor biology and better evaluate treatment response.

Using 18 F-FDG PET/CT to Detect an Occult Mesenchymal Tumor Causing Oncogenic Osteomalacia

Oncogenic osteomalacia is a rare paraneoplastic syndrome characterized by renal phosphate excretion, hypophosphatemia, and osteomalacia. This syndrome is often caused by tumors of mesenchymal origin. Patients with oncogenic osteomalacia have abnormal bone mineralization, resulting in a high frequency of fractures. Tumor resection is the treatment of choice, as it will often correct the metabolic imbalance. Although oncogenic osteomalacia is a potentially curable disease, diagnosis is difficult and often delayed because of the small size and sporadic location of the tumor. Bone scintigraphy and radiography best characterize osteomalacia; magnetic resonance imaging findings are nonspecific. Here, we report a case of oncogenic osteomalacia secondary to a phosphaturic mesenchymal tumor that was successfully detected by 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). This case illustrates the advantages of 18F-FDG PET/CT in detecting the occult mesenchymal tumor that causes oncogenic osteomalacia.

Evaluation of Bone Metastasis from Hepatocellular Carcinoma Using 18F-FDG PET/CT and 99mTc-HDP Bone Scintigraphy: Characteristics of Soft Tissue Formation

PurposeBone metastasis from hepatocellular carcinoma (HCC) can present with soft tissue formation, resulting in oncologic emergency. Contrast-enhanced FDG PET/CT and bone scintigraphy were compared to evaluate characteristics of bone metastases with or without soft tissue formation from HCC.MethodsOf 4,151 patients with HCC, 263 patients had bone metastases. Eighty-five patients with bone metastasis from HCC underwent contrast-enhanced FDG PET/CT. Fifty-four of the enrolled subjects had recent 99mTc-HDP bone scintigraphy available for comparison. Metastatic bone lesions were identified with visual inspection on FDG PET/CT, and maximum standardized uptake value (SUVmax) was used for the quantitative analysis. Confirmation of bone metastasis was based on histopathology, combined imaging modalities, or serial follow-up studies.ResultsForty-seven patients (55%) presented with soft tissue formation, while the remaining 38 patients presented without soft tissue formation. Frequent sites of bone metastases from HCC were the spine (39%), pelvis (19%), and rib cage (14%). The soft-tissue-formation group had more frequent bone pain (77 vs. 37%, p < 0.0001), higher SUVmax (6.02 vs. 3.52, p < 0.007), and higher incidence of photon defect in bone scintigraphy (75 vs. 0%) compared to the non-soft-tissue-formation group. FDG PET/CT had higher detection rate for bone metastasis than bone scintigraphy both in lesion-based analysis (98 vs. 53%, p = 0.0015) and in patient-based analysis (100 vs. 80%, p < 0 .001).ConclusionsBone metastasis from HCC showed a high incidence of soft tissue formation requiring emergency treatment. Although the characteristic findings for soft tissue formation such as photon defect in bone scintigraphy are helpful in detection, overall detectability of bone metastasis is higher in FDG PET/CT. Contrast-enhanced PET/CT will be useful in finding and delineating soft-tissue-forming bone metastasis from HCC.

Usefulness of Additional SPECT/CT Identifying Lymphatico-renal Shunt in a Patient with Chyluria

Lymphoscintigraphy is known to be a useful and non-invasive modality for the evaluation of lymphatic abnormality. However, lymphoscintigraphy has limitations in evaluating chyluria because of its lack of anatomical information. Additional single-photon emission computed tomography (SPECT) combined with computed tomography (CT) was considered to be potentially helpful in detecting the abnormal lymphatico-renal communication. A 20-year-old male patient was referred to our hospital for evaluation of recurrent chyluria. During the third recurrence of chyluria, additional SPECT/CT along with lymphoscintigraphy was performed for evaluation. From the combined SPECT/CT images, lymphatic drainage of radiotracers to the kidney was well visualized, helping diagnosis of a patient with chyluria.

18F-FDG PET/CT in hepatocellular carcinoma: Detection of bone metastasis and prediction of prognosis

ObjectiveThe purpose of this study was to assess the diagnostic accuracy and prognostic value of 18F-fluorodeoxyglucose PET/computed tomography (CT) in bone metastases from hepatocellular carcinoma (HCC). Patients and methodsOf 3912 consecutive HCC patients, 67 patients who had undergone both PET/CT and bone scintigraphy (BS) within a 3-month interval were evaluated. ResultsBone metastases were most frequently found in the pelvis (20%), followed by the lumbar spine (14%) and long bones (13%). PET/CT was significantly more sensitive than BS in region-based analyses, with 273 confirmed bone metastases (96.7 vs. 52.7%, respectively; P<0.001), and in patient-based analyses (99 vs. 85%; P=0.042). The median survival period was 5 (range, 0.4–18) months. On univariate analysis, poor prognostic factors included age (<60 years), multiple bone metastases, lymph node metastasis, high serum &agr;-fetoprotein (≥400 IU/ml), Child–Pugh class B, and high maximum standardized uptake value (SUVmax) of bone metastasis (>5.0). Large metabolic volume (≥200 cm3) of bone metastasis was another poor prognostic factor. On Cox regression analysis, high &agr;-fetoprotein was the only poor prognostic factor with statistical significance. ConclusionPET/CT was more sensitive than BS in bone metastasis from HCC by both patient-based and region-based analyses, and offered additional information on survival. PET/CT can be helpful in early diagnosis and opportune treatment of bone metastasis from HCC.

Hemodynamic Significance of Internal Carotid or Middle Cerebral Artery Stenosis Detected on Magnetic Resonance Angiography.

Purpose We evaluated hemodynamic significance of stenosis on magnetic resonance angiography (MRA) using acetazolamide perfusion single photon emission computed tomography (SPECT). Materials and Methods Of 171 patients, stenosis in internal carotid artery (ICA) and middle cerebral artery (MCA) (ICA-MCA) on MRA and cerebrovascular reserve (CVR) of MCA territory on SPECT was measured using quantification and a 3-grade system. Stenosis and CVR grades were compared with each other, and their prognostic value for subsequent stroke was evaluated. Results Of 342 ICA-MCA, 151 (44%) presented stenosis on MRA; grade 1 in 69 (20%) and grade 2 in 82 (24%) cases. Decreased CVR was observed in 9% of grade 0 stenosis, 25% of grade 1, and 35% of grade 2. The average CVR of grade 0 was significantly different from grade 1 (p<0.001) and grade 2 stenosis (p=0.007). In quantitative analysis, average CVR index was -0.56±7.91 in grade 0, -1.81±6.66 in grade 1 and -1.18±5.88 in grade 2 stenosis. Agreement between stenosis and CVR grades was fair in patients with lateralizing and non-lateralizing symptoms (κ=0.230 and 0.346). Of the factors tested, both MRA and CVR were not significant prognostic factors (p=0.104 and 0.988, respectively), whereas hypertension and renal disease were significant factors (p<0.05, respectively). Conclusion A considerable proportion of ICA-MCA stenosis detected on MRA does not cause CVR impairment despite a fair correlation between them. Thus, hemodynamic state needs to be assessed for evaluating significance of stenosis, particularly in asymptomatic patients.

Clinical Performance of Whole-Body 18F-FDG PET/Dixon-VIBE, T1-Weighted, and T2-Weighted MRI Protocol in Colorectal Cancer.

Purpose The aim of this study was to investigate the clinical performance of whole-body 18F-FDG PET/Dixon–volume-interpolated breath-hold examination (Dixon-VIBE), T1-weighted, and T2-weighted MRI protocol in patients with colorectal cancer. Patients and Methods A total of 59 patients with colorectal cancer were enrolled in this study. Each patient had one of the following clinical conditions: initial stage before therapy, stage after neoadjuvant therapy, suspicious colorectal liver metastases, and colorectal liver metastases after chemotherapy. Fourteen patients had primary colorectal cancer, whereas 38 patients had a total of 132 hepatic lesions, 53 lesions existed before chemotherapy, and 79 lesions appeared after chemotherapy. The primary stage and metastases images were obtained using our PET/Dixon-VIBE/T1/T2 MRI protocol and were analyzed by 2 nuclear medicine physicians. Diagnostic accuracy was compared with contrast-enhanced MRI images, which were based on surgical pathology results. Results The sensitivity of our imaging protocol for primary colorectal cancer was 100% (14/14). T and N stage both showed 92.9% (13/14) accuracy. Of all 132 hepatic lesions, 115 metastatic lesions were analyzed, and 17 benign lesions were excluded (6 were during pretreatment cases, and 11 were during posttreatment cases). In pretreatment metastatic lesions (n = 47), the sensitivities of our protocol and dedicated MRI were 95.7% (45/47) and 100% (47/47), respectively. In posttreatment lesions (n = 68), sensitivities of our protocol and dedicated MRI were 75% (51/68) and 91.2% (62/68), respectively. Conclusions Whole-body PET/Dixon-VIBE/T1/T2 MRI protocol is clinically useful for TNM staging and chemonaive hepatic metastasis in colorectal cancer.

A Hepatoid Adenocarcinoma of the Stomach Evaluated With 18F-FDG PET/CT: Intense 18F-FDG Uptake Contrary to the Previous Report

The condition of a 55-year-old man was diagnosed with unresectable advanced gastric cancer, and initial biopsy revealed adenocarcinoma. On evaluation of treatment response after chemotherapy, F-FDG PET/CT showed large residual stomach cancer with increased FDG uptake (SUVmax, 13.6), lymph node metastasis with mild FDG uptake (SUVmax, 2.5), and no distant metastasis. Palliative subtotal gastrectomy was done, and the finding was hepatoid adenocarcinoma. Compared with the previous report of Pan et al (Clin Nucl Med. 2011;36:1137-1139), our patient had more increased FDG uptake of SUVmax (13.6 vs 1.9) in the gastric mass and lymph node metastases but no liver metastasis.