Intense Diffuse Uptake of 68Ga-FAPI-04 in the Breasts Found by PET/CT in a Patient With Advanced Nasopharyngeal Carcinoma.

ABSTRACT: The physiological uptake of 68Ga-FAPI-04 due to the change of the internal environment is little known. We report the case of a 45-year-old woman who was highly suspected to have advanced nasopharyngeal carcinoma. 18F-FDG and 68Ga-FAPI-04 PET/CT was performed for evaluating the disease. Both PET and CT with different tracers detected the primary nasopharyngeal carcinoma and metastases in right neck lymph nodes, liver, and bones. To our surprise, intense diffuse uptake of 68Ga-FAPI-04 was found in both breasts, which might be due to the hormone stimulation because the patient received 68Ga-FAPi-04 PET/CT just at the period of ovulation.

18F-FDG PET/CT imaging findings in anaplastic large cell lymphoma, a rare subtype of lymphoma.

OBJECTIVE: To investigate the 18F-FDG PET/CT imaging manifestations for anaplastic large cell lymphoma (ALCL), a rare subtype of T/NK cell lymphoma. METHODS: Fifty patients with ALCL, including 32 anaplastic lymphoma kinase (ALK)-positive patients and 18 ALK-negative patients, were enrolled. The positive detection, maximal standardized uptake value (SUVmax), and distribution of nodal and extranodal involvement were recorded and analysed. Fifty patients with diffuse large B cell lymphoma (DLBCL) were collected as a control group. RESULTS: ALCL lesions were demonstrated to be 18F-FDG-avid tumours with a mean SUVmax of 19.4 ± 12.6. Most (76%) ALCL patients presented with stage III-IV disease, and nodal and extranodal involvement occurred in 74.0 and 72.0% of the patients, respectively. ALCL and DLBCL showed many similarities in tumour stage, 18F-FDG uptake and tumour involvement (P > 0.05), although the preferred extranodal organs of involvement (bone and the gastrointestinal tract, respectively) were different (P < 0.05). Compared to ALK-negative lesions, a higher uptake of 18F-FDG was found in the ALK-positive lesions (SUVmax: 22.1 ± 14.3 vs. 15.1 ± 6.6, t = 2.354, P = 0.023). ALK-positive ALCL was more likely to involve the lymph nodes than ALK-negative ALCL (84.3% vs. 55.5%, χ2 = 4.973, P = 0.043), while ALK-negative ALCL was more prone to involve the extranodal organs compared to ALK-positive ALCL (88.9% vs. 62.5%, χ2 = 3.979, P = 0.046). CONCLUSION: The present study demonstrated that ALCL is a systemic 18F-FDG-avid lymphoma with many imaging manifestations similar to DLBCL on PET/CT. The present study also showed that ALK expression actually influenced tumour 18F-FDG uptake and lesion distribution. These findings may be useful to improve the understanding of the biological characteristics of ALCL.

Gummatous Syphilis Mimicking Malignant Bone Tumor on FDG PET/CT.

A 47-year-old woman suffered worsening pain in the waist and numbness in the right thigh for 1 month. MRI was performed to determine the cause, which detected an osteolytic lesion in the T12 vertebral body, suggestive of possible bone metastasis. FDG PET/CT scan was undertaken to detect the primary tumor, which only showed the same isolated lesion in the T12 without any other abnormal hypermetabolic lesion. The pathology following vertebrectomy revealed granulomatous infection. The diagnosis of osseous syphilis was eventually made following a subsequent positive Treponema pallidum serological test.

A Rare Case of Neutrophil-Rich, ALK-Negative Anaplastic Large Cell Lymphoma in the Lung Mimicking a Pulmonary Abscess on 18F-FDG PET/CT.

A 21-year-old man complained of cough, fever, and hemoptysis for 15 days. Peripheral neutrophil cell (33.8 × 10/L) was markedly increased, and a mass in the left lung was detected by chest radiography. F-FDG PET/CT was referred for characterizing the lesion and found a large mass with multiple cavities in the left lung, which had markedly high uptake of F-FDG, mimicking pulmonary abscess. Surprisingly, the lesion was eventually proved to be neutrophil-rich anaplastic large cell lymphoma. After 4 cycles' chemotherapy, the lesion shrank significantly.

Construction and Evaluation of the Tumor-Targeting, Cell-Penetrating Multifunctional Molecular Probe iCREKA.

A novel tumor stroma targeting and membrane-penetrating cyclic peptide, named iCREKA, was designed and labeled by fluorescein isothiocyanate (FITC) and positron emitter 18F to build the tumor-targeting tracers. The FITC-iCREKA was proved to have significantly higher cellular uptake in the glioma U87 cells in the presence of activated MMP-2 than that in absence of activated MMP-2 by cells fluorescence test in vitro. The tumor tissue fluorescence microscope imaging demonstrated that FITC-iCREKA accumulated in the walls of the blood vessels and the surrounding stroma in the glioma tumor at 1 h after intravenous injection. While at 3 h after injection, FITC-iCREKA was found to be uptaken in the tumor cells. However, the control FITC-CREKA can only be found in the tumor stroma, not in the tumor cells, no matter at 1 h or 3 h after injection. The whole-animal fluorescence imaging showed that the glioma tumor could be visualized clearly with high fluorescence signal. The microPET/CT imaging further demonstrated that 18F-iCREKA could target U87MG tumor in vivo from 30 min to 2 h after injection. The present study indicated the iCREKA had the capacity of tumor stroma targeting and the membrane-penetrating. It was potential to be developed as the fluorescent and PET tracers for tumor imaging.

Low glucose metabolism in hepatocellular carcinoma with GPC3 expression.

AIM: To investigate the relationship between glucose metabolism and glypican-3 (GPC3) expression in hepatocellular carcinoma (HCC). METHODS: Immunohistochemical staining of pathological samples for GPC3 and glucose transporter 1 (GLUT1), and whole-body 18F-FDG PET/CT for measuring tumour glucose uptake were performed in 55 newly diagnosed HCC patients. The maximum standard uptake value (SUVmax) and tumour-to-non-tumourous liver uptake (T/NT) ratio were used to quantify 18F-FDG uptake. In vitro18F-FDG uptake assay of GPC3-expressing HepG2 and non-GPC3-expressing RH7777 cells was used to examine the effect of GPC3 in cellular glucose metabolism. The relationships between GPC3 expression and 18F-FDG uptake, GLUT1 expression, tumour differentiation, and other clinical indicators were analysed using Spearman rank correlation, univariate and multiple logistic regression analyses. RESULTS: Positive GPC3 expression was observed in 67.3% of HCC patients, including 75.0% of those with well or moderately differentiated HCC and 36.4% of those with poorly differentiated HCC. There was an inverse relationship between GPC3 expression and SUVmax (Spearman correlation coefficient = -0.281, P = 0.038) and a positive relationship between GLUT1 expression and SUVmax (Spearman correlation coefficient = 0.681, P < 0.001) in patients with HCC. Univariate analysis showed that two glucose metabolic parameters (SUVmax and T/NT ratio), tumour differentiation, lymph node metastasis, and TNM stage were all significantly associated with GPC3 expression (P < 0.05), whereas GLUT1 expression, sex, age, tumour size, intrahepatic lesion number, and distant metastasis showed no statistical association (P > 0.05). Further multivariate analysis revealed that only the T/N ratio was significantly correlated with GPC3 expression in patients with HCC (P < 0.05). In vitro assay revealed that the uptake of 18F-FDG in GPC3-expressing HepG2 cells was significantly lower than that of non-GPC3-expressing RH7777 cells (t = -20.352, P < 0.001). CONCLUSION: The present study demonstrated that GPC3 expression is inversely associated with glucose metabolism, suggesting that GPC3 may play a role in regulating glucose metabolism in HCC.

Imaging the expression of glypican-3 in hepatocellular carcinoma by PET.

The glypican-3 (GPC3) receptor is overexpressed in hepatocellular carcinoma (HCC) and is a potential diagnostic and therapeutic target. GPC3-targeted molecular imaging will be helpful to differentiate diagnosis and guide therapy. In the present study, we will develop a novel PET probe for imaging the expression of GPC-3. L5 (sequence: RLNVGGTYFLTTRQ), a GPC3 targeting peptide, was labeled with 5-carboxyfluorescein (FAM) and 18F-fluoride. Cell binding tests were performed to identify the binding specificity of FAM-L5 and 18F radiolabeled peptide. MicroPET/CT imaging was used to determine the potential of a novel PET tracer for visualizing HCC tumors with a high expression of GPC3. In vitro binding tests showed that the uptake of FAM-L5 in HepG2 cells (high expression of GPC3) was significantly higher than that of HL-7702 cells (negative expression of GPC3) (mean fluorescent intensity: 14,094 ± 797 vs. 2765 ± 314 events, t = 32.363, P = 0.000). Confocal fluorescent imaging identified that FAM-L5 accumulated where the GPC3 receptor was located. A novel PET tracer (18F-AlF-NODA-MP-6-Aoc-L5) was successfully labeled by chelation chemistry. In vitro cell uptake studies showed that 18F-AlF-NODA-MP-6-Aoc-L5 can bind to HepG2 tumor cells and was stable in PBS and mouse serum stability tests. MicroPET/CT showed that HepG2 tumors could be clearly visualized with a tumor/muscle ratio of 2.46 ± 0.53. However, the tumor/liver ratio was low (0.93 ± 0.16) due to the high physiological uptake in the liver. This study demonstrates that FAM and the 18F-labeled L5 peptide can selectively target HCC with a high expression of GPC3 in vitro and in vivo. 18F-AlF-NODA-MP-C6-L5 has the potential to be a GPC3 target tracer but requires some chemical modifications to achieve a high enough tumor/liver ratio for detection of the tumor in the liver.

Multifunctional superparamagnetic nanoparticles conjugated with fluorescein-labeled designed ankyrin repeat protein as an efficient HER2-targeted probe in breast cancer.

Based on the discordance of human epidermal growth factor receptor-2 (HER2) expression between primary and metastatic/recurrent breast cancer, HER2 molecular imaging, which had potential to systemically assess and dynamically monitor HER2 expression, might improve the selection of patients for anti-HER2 therapy. In this study, designed ankyrin repeat protein (DARPin) G3, a novel binding protein with picomolar affinity for HER2, was used and multifunctional superparamagnetic nanoparticles modified with fluorescein-5-maleimide-labeled DARPin G3 (SPIO-G3-5MF) were developed for HER2 imaging. Our results showed that SPIO-G3-5MF nanoparticles, which possessed uniform size of about 100 nm, favorable dispersity and low cytotoxicity, could selectively bind to HER2-positive breast cancer cells even in the presence of trastuzumab. Biodistribution assay demonstrated that abundant accumulation and long retention of SPIO-G3-5MF were observed in HER2-positive transplantation breast tumors although a portion of SPIO-G3-5MF nanoparticles were unavoidably captured by liver and spleen. Further MR imaging revealed that SPIO-G3-5MF could selectively image HER2-positive transplantation breast tumors, yielding remarkable T2 signal reduction (50.33 ± 2.90% at 6 h and 47.29 ± 9.36% at 24 h). Our study suggested that SPIO-G3-5MF might be a promising MR molecular probe for diagnosing and monitoring HER2 expression state of breast cancer in the future.

[Combined use of thin-section CT and 18F-FDG PET/CT for characterization of solitary pulmonary nodules].

OBJECTIVE: To investigate whether fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) combined with thin-section CT improves the diagnostic performance for solitary pulmonary nodules (SPNs). METHODS: A total of 267 patients underwent examinations with 18F-FDG PET/CT and thin-section CT for evaluating the SPNs with undetermined nature, which was further confirmed by pathological examination or clinical follow-up. The performance of two diagnostic criteria based on findings in PET/CT alone (Criterion 1) and in PET/CT combined with thin-section CT (Criterion 2) were compared. RESULTS: Thin-section CT provided greater diagnostic information for SPNs in 84.2% of the patients. Compared with Criterion 1, the diagnosis based on Criterion 2 significantly increased the diagnostic sensitivity (80.4% vs 91%, P<0.01) and accuracy (76.4% vs 87.2%, P<0.01) for lung cancer. The lesion size and the CT features including lobulation, air bronchogram, and feeding vessel, but not SUVmax, were all helpful for characterizing non-solid SPNs. Thin-section CT rectified diagnostic errors in 50% (20/40) of the cancerous lesions, which had been diagnosed as benign by PET due to their low metabolism. For non-solid SPNs, Criterion 2 showed a significantly higher diagnostic sensitivity than Criterion 1 (90.0% vs 40.0%, P=0.000) but their diagnostic specificity were comparable (75.2% vs 58.3%, P=0.667). For solid nodules, the use of thin-section CT resulted in no significant improvement in the diagnostic performance (P<0.05). CONCLUSION: The combination of PET/CT and thin-section CT creates a synergistic effect for the characterization of SPNs, especially non-solid nodules.

Whole-body 18F-FDG PET/CT for M staging in the patient with newly diagnosed nasopharyngeal carcinoma: Who needs?

OBJECTIVE: Although whole-body fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) (18F-FDG PET/CT) is commonly used for M staging of newly diagnosed nasopharyngeal carcinoma (NPC), some patients may not benefit from this procedure. The present study investigated which patients require this modality for M staging. METHODS: Whole-body 18F FDG PET/CT results and clinical data were collected for 264 patients with newly diagnosed NPC. The relationships between distant metastasis and age, gender, pathological type, lesion size, SUVmax-T, T staging, N staging, SUVmax-N and Epstein-Barr virus (EBV) quantity were retrospectively analysed to identify factors associated with increased risk. RESULTS: Of the 264 patients, only 37 (14.0%) were diagnosed with distant metastasis. Using multiple logistic regression analysis, EBV-positivity (OR=13.1; 95% CI:1.61,106.80), N staging (OR=3.05; 95% CI:1.41,6.63) and T staging (OR=2.16; 95% CI:1.10, 4.24) were significantly related to distant metastasis (all P<0.05). EBV DNA levels≥9000copies/ml, N3 stage and T4 stage were identified as high risk factors. A low risk of distant metastasis was found in patients with 0-1 risk factors and in those with 2 specific risk factors, T3/T4 and N2/N3 staging. Patients with EBV DNA levels ≥9000copies/ml and N3 or T4 staging and those with 3 risk factors had a medium or high risk, with a much higher incidence of distant metastasis (χ2=29.896, P=0.000), and needed a whole-body 18F FDG PET/CT for M staging. CONCLUSIONS: Due to the low incidence of distant metastasis, only patients with medium or high risk need to undergo a whole-body scan.

PET/CT for differentiating between tuberculous peritonitis and peritoneal carcinomatosis: The parietal peritoneum.

OBJECTIVES: Tuberculous peritonitis (TBP) mimics peritoneal carcinomatosis (PC). We aimed to investigate the discriminative use of PET/CT findings in the parietal peritoneum. MATERIALS AND METHODS: Parietal peritoneal PET/CT findings from 76 patients with TBP (n = 25) and PC (n = 51) were retrospectively reviewed. The lesion locations were noted as right subdiaphragmatic, left subdiaphragmatic, right paracolic gutters, left paracolic gutters, and pelvic regions. The distribution characteristic consisted of a dominant distribution in the pelvic and/or right subdiaphragmatic region (susceptible area for peritoneal implantation, SAPI) (SAPI distribution), a dominant distribution in the remaining regions (less-susceptible area for peritoneal implantation, LSAPI) (LSAPI distribution), or a uniform distribution. PET morphological patterns were classified as F18-fluorodeoxyglucose (F-FDG) uptake in a long beaded line (string-of-beads F-FDG uptake) or in a cluster (clustered F-FDG uptake) or focal F-FDG uptake. CT patterns included smooth uniform thickening, irregular thickening, or nodules. RESULTS: More common findings in the parietal peritoneum corresponding to TBP as opposed to PC were (a) ≥4 involved regions (80.0% vs 19.6%), (b) uniform distribution (72.0% vs 5.9%), (c) string-of-beads F-FDG uptake (76.0% vs 7.8%), and (d) smooth uniform thickening (60.0% vs 7.8%) (all P < 0.001), whereas more frequent findings in PC compared with TBP were (a) SAPI distribution (78.4% vs 28.0%), (b) clustered F-FDG uptake (56.9% vs 20.0%), (c) focal F-FDG uptake (21.6% vs 4.0%), (d) irregular thickening (51.0% vs 12.0%), and (e) nodules (21.6% vs 4.0%) (P < 0.001, P < 0.05, P > 0.05, P < 0.05, P > 0.05, respectively). CONCLUSION: Our data show that PET/CT findings in the parietal peritoneum are useful for differentiating between TBP and PC.

18F-FDG super bone marrow uptake: A highly potent indicator for the malignant infiltration.

The present study was performed to investigate whether the markedly 2-deoxy-2-(fluorine-18) fluoro-D-glucose (F-FDG) uptake in the bone marrow (BM) is a presentation of malignant infiltration (MI).Super bone marrow uptake (super BMU) was used to name the markedly F-FDG uptake on BM, which was similar to or higher than that of the brain. From April 2008 to December 2015, 31 patients with such presentation were retrospectively reviewed. The F-FDG uptake was semiquantified using SUVmax and BM to cerebellum (BM/C) ratio. The origin of super BMU was diagnosed by pathology. Some blood parameters, as well as fever, were also collected and analyzed. For comparison, 106 patients with mildly and moderately uptake in BM and 20 healthy subjects were selected as the control group.Bone marrow MI was diagnosed in 93.5% (29/31) patients with super BMU, which mostly originated from acute leukemia and highly aggressive lymphoma. The super BMU group had markedly higher F-FDG uptake in the BM than those of mildly and moderately uptake, and the control subjects (all P = 0.000) and the BM/C ratio reached a high of 1.24 ±â€Š0.36. The incidence of bone marrow MI in the super BMU group was markedly higher than that of mildly and moderately uptake (93.5% vs 36.8%, P = 0.000). Based on the receiver operating characteristic analysis, when cut-off values of BM/C and SUVmax were set at 0.835 and 6.560, the diagnostic specificity for bone marrow MI reached the high levels of 91.4% and 95.7%, respectively. In 15 patients with bone marrow MI, the extra-BM malignant lesions were simultaneously detected by F-FDG PET/CT. The liver and the nasal cavity involvements were only found in the patients with lymphoma, but not in those with leukemia. A decrease of leukocyte, hemoglobin, and platelet counts was noted in 48.4%, 86.2%, and 51.5% of patients with bone marrow MI, respectively.The present study revealed that super BMU was a highly potent indicator for the bone marrow MI.

[18F-FDG PET/CT findings of primary intestinal lymphoma: analysis of 23 cases].

OBJECTIVE: To investigate the characteristic 18F-FDG PET/CT findings in patients with primary intestinal lymphoma (PIL). METHODS: We collected the clinical and 18F-FDG PET/CT data of 23 patients with PIL who underwent 18F-FDG PET/CT in our center between January, 2005 and January, 2016. The location, morphologies and metabolic features of the lesions were analyzed in these patients. RESULTS: In the 23 PIL patients, diffusive large B cell lymphoma (DLBCL) and enteropathy- associated T cell lymphoma (EATL) were the primary histopathological types, accounting for 47.8% and 43.4% of the total patients, respectively. The ileum, ileocecus and ascending colon were the most commonly compromised locations (57.0%). All the 42 intestinal lesions showed 18F-FDG-avid foci with a mean SUVmax of 15.2∓8.1 (range 3.6-33.7), and no significant difference was found in SUVmax between DLBCL and EATL groups (t=1.851, P=0.073). Diffusive regular or irregular intestinal wall thickening was the primary CT finding in PIL lesions without significant difference between the two groups (χ2=0.426, P=0.514). The aneurismal sign was found in 26.2% (11/42) lesions, more commonly seen in the patients with DLBCL than in those with EATL (χ2=8.101, P=0.004). PET/CT detected abdominal lymph node involvement of lymphoma was detected in 56.5% of the patients, and a small quantity of asites was seen in 30.4% of the patients. CONCLUSION: PIL presents with characteristic imaging features in 18F-FDG PET/CT. 18F-FDG PET/CT is a sensitive imaging modality for detecting inter- and extra-intestinal lesions of PIL and displays characteristic imaging features of the disease.

False-Positive Finding on 18F FDG PET/CT: Report of a Rare Case With Xanthogranulomatous Inflammation in the Spinal Epidural Space.

Xanthogranulomatous inflammation in the spinal epidural space is extremely rare. We report a case of a 62-year-old man with a xanthogranulomatous inflammation in the spinal epidural space mistaken for lymphoma because of its avid F FDG uptake on PET/CT. This case emphasizes the need for caution when evaluating a spinal epidural mass using F FDG PET/CT as xanthogranulomatous inflammation can induce a false-positive reading on F-FDG PET/CT.

Usefulness and pitfalls of F-18-FDG PET/CT for diagnosing extramedullary acute leukemia.

PURPOSE: It is very important to identify whether there is extramedullary involvement in acute leukemia (AL), especially in those with recurrent disease. This retrospective study aimed to assess the role of (18)F-FDG PET/CT for diagnosing extramedullary AL. MATERIALS AND METHODS: PET/CT examinations were performed in 9 patients with newly diagnosed AL, and 70 patients suspected to have recurrent AL. All the patients were diagnosed with AL by bone marrow biopsy. The diagnosis of extramedullary lesions was established according to the combination of pathology, physical examination, and imaging techniques including magnetic resonance imaging (MRI) and PET/CT, and/or cerebrospinal fluid (CSF) cytologic testing, and clinical follow-up. RESULTS: Of the 79 patients, including 34 acute lymphocytic leukemia (ALL) and 45 acute myeloid leukemia (AML) cases, 30 patients were diagnosed with extramedullary AL. (18)F-FDG PET/CT demonstrated (18)F-FDG positive lesions in the extramedullary regions in 42 patients. Among them, 28 patients were diagnosed to have extramedullary AL and the other 14 were diagnosed with non-hematological malignancies (false positive disease). The sensitivity, specificity, and accuracy of (18)F-FDG PET/CT in diagnosing extramedullary involvement of AL were 93.3% (28/30), 71.4% (35/49), and 79.7%, respectively. The (18)F-FDG uptake of lesions was not significantly different between extramedullary AL and false positive cases (SUVmax: 6.66 ± 2.65 vs. 5.85 ± 1.88, t=1.275, P=0.206). The FDG uptake of extramedullary AL between ALL and AML were also not significantly different (SUVmax: 7.01 ± 2.82 vs. 6.10 ± 2.29, t=1.332, P=0.188). The predominant locations of extramedullary AL were the spleen, soft tissue, lymph nodes, central nerve system, liver, testis, and kidney. A total of 48.2% (27/56) of extramedullary AL lesions presented as diffuse FDG uptake compared with 6.25% (1/16) in the false positive lesions (χ(2)=9.221, P=0.002). CONCLUSION: (18)F-FDG PET/CT is a sensitive, but not specific imaging modality for diagnosing extramedullary AL. Diffuse (18)F-FDG uptake in extramedullary lesions may indicate leukemia involvement.

18F-FDG PET/CT in differentiating malignant from benign origins of obstructive jaundice.

BACKGROUND: The various origins of obstructive jaundice make the diagnosis of the disease difficult. This study was undertaken to evaluate the role of 18F-FDG PET/CT in differentiating malignant from benign origins of obstructive jaundice and to quantify the added value of 18F-FDG PET/CT over conventional imaging (enhanced CT and/or MRI). METHODS: Eighty-five patients with obstructive jaundice who underwent 18F-FDG PET/CT within 2 weeks after enhanced CT and/or MRI were reviewed retrospectively. All 18F-FDG PET/CT images were independently evaluated by 2 nuclear medicine physicians who were unaware of other imaging data; differences were resolved by consensus of the physicians. All conventional imaging interpretations, according to the medical records, were reviewed by 2 radiologists to determine the potential value. Final diagnoses were based on histological or surgical findings. RESULTS: Sixty-six patients were diagnosed with malignancies, and 19 patients with benign lesions. The maximum standardized uptake values for malignant and benign lesions causing biliary obstruction were 8.2+/-4.4 and 4.0+/-5.0, respectively (P<0.05). The sensitivity, specificity, and overall accuracy for differentiating malignant from benign origins with 18F-FDG PET/CT were 86.4% (57/66), 73.7% (14/19), and 83.5% (71/85), respectively. 18F-FDG PET/CT in conjunction with conventional imaging changed the sensitivity, specificity, and overall accuracy of conventional imaging alone from 75.8% (50/66) to 95.5% (63/66) (P<0.05), 68.4% (13/19) to 57.9% (11/19) (P>0.05), and 74.1% (63/85) to 87.1% (74/85) (P<0.05), respectively. CONCLUSIONS: 18F-FDG PET/CT is of great value in differentiating malignant from benign origins of obstructive jaundice and is a useful adjuvant to conventional imaging. 18F-FDG PET/CT should be recommended for further etiological clarification.

Use of Labelled tLyP-1 as a Novel Ligand Targeting the NRP Receptor to Image Glioma.

BACKGROUND: Neuropilin (NRP) receptors are overexpressed in glioma tumor tissue, and therefore may be a potential target for imaging markers. We investigated whether labelled tLyP-1, an NRP targeting peptide, could be used as the targeting ligand for developing reagents for imaging glioma tumors. METHODS: The tLyP-1 peptide (CGNKRTR) was labeled with 5-carboxyfluorescein (FAM) or 18F-fluoride. A control peptide (MAQKTSH) was also labeled with FAM. The in vitro binding between FAM-tLyP-1 and U87MG cells and in vivo biodistribution of FAM-tLyP-1 in a U87MG glioblastoma xenograft model (nude mouse) were determined. The in vivo biodistribution of 18F-tLyP-1 was also determined by microPET/CT. RESULTS: In vitro, FAM-tLyP-1 was strongly taken up by U87MG cells at very low concentrations (1 µM). In vivo, FAM-tLyP-1 accumulated in glioma (U87MG) tumors, but uptake was minimal in the normal brain tissue 1 h after administration. The distribution of FAM-tLyP-1 in the tumor tissue was consistent with expression of NRP1. The tumor/brain fluorescence intensity ratio in mice treated with FAM-tLyP-1 was significantly higher than the control FAM-labeled peptide 1 h after administration (3.44 ± 0.83 vs. 1.32 ± 0.15; t = 5.547, P = 0.001). Uptake of FAM-tLyP-1 in glioma tumors could be blocked by administering an excess of non-conjugated tLyP-1 peptide. [Lys4] tLyP-1 was labeled with 18F to synthesis a PET (18F-tLyP-1). MicroPET/CT imaging showed the tumor was visualized clearly with a high tumor/brain radiolabel ratio at 60 min (2.69 ± 0.52) and 120 min (3.11 ± 0.25). CONCLUSION: Taken together, our results suggest that tLyP-1 could be developed as a novel fluorescent or radio labelled tracer for imaging glioma.

Utility of F-18 FDG PET/CT on the evaluation of primary bone lymphoma.

PURPOSE: Primary bone lymphoma (PBL) is a rare type of malignant lymphoma. Few data have been reported regarding the utility of F-18 FDG PET/CT in this disease. The aim of this study was to assess the role of F-18 FDG PET/CT in the diagnosis and therapeutic effect evaluation of PBL. MATERIALS AND METHODS: A total of 19 consecutive patients with PBL were enrolled. Whole-body PET/CT scan was performed for all patients. The diagnosis of PBL was established by histopathology and immunohistochemistry. RESULTS: F-18 FDG PET/CT was positive in 94.7% (18/19) of patients. Uptake of FDG in lesions was intense with SUVmax of 15.14 ± 11.82. Multiple involved lesions were found in 47.4% (9/19) patients, while 52.6% presented with a single involved lesion. Based on the lesions, PET detected 98.9% (87/88) lesions. Among them, 71.6% (63/88) lesions were found to be located in axial skeleton and 28.4% (25/88) in the extremity skeleton. FDG PET/CT also found the lesions infiltrate to the surrounding soft tissue in 84.2% (16/19) patients. On the syn-modality CT, the bone destruction was noted in 43.2% (38/88) of the lesions, of which 50.0% lesions presented as slight change in bone density and 50.0% as severe change. The diagnostic sensitivity of PET was much higher than that of CT (98.9% vs. 43.2%, P=0.000). PET/CT was performed for evaluation of treatment response in 13 patients. In 12 patients with complete response(CR), PET/CT found the 25 lesions were F-18 FDG fully resoluted after treatment, however, bone destruction was still presented in 72.0% (18/25) lesions. CONCLUSIONS: The present study suggests that F-18 FDG PET/CT was a sensitive imaging modality for diagnosis and treatment response evaluation of PBL.

Utility of 18F-FDG PET/CT in the diagnosis and staging of extramammary Paget's disease.

PURPOSE: Extramammary Paget's disease (EMPD) is rare, and limited data have been reported on the utilization of fluorine-18 fluorodeoxyglucose PET/computed tomography ((18)F-FDG PET/CT) in this disease. The aim of this study is to evaluate the role of (18)F-FDG PET/CT in the diagnosis and staging of EMPD. MATERIALS AND METHODS: Whole-body (18)F-FDG PET/CT images of 10 patients with newly diagnosed or recurrent EMPD were retrospectively analyzed. The lesion with increased (18)F-FDG uptake was considered positive and was measured using the maximum standardized uptake value (SUV(max)). The results of PET/CT were compared by conventional staging examinations. RESULTS: All malignant lesions showed increased (18)F-FDG uptake, except for some small lung metastases. Whole-body (18)F-FDG PET/CT detected all primary lesions in four newly diagnosed patients and recurrences in the primary sites in two patients. Two thick lesions showed intense uptake of (18)F-FDG (SUV(max): 14.9 and 7.5) whereas four thin lesions had only mild (18)F-FDG uptake (mean SUV(max): 3.25 ± 0.24). A false-positive result was found in one patient with suspected primary recurrence. (18)F-FDG PET/CT also detected lymph node metastases in six patients, bone metastases in five patients, liver metastases in two patients, lung metastases in one patient, and an adrenal gland metastasis in one patient. Compared with conventional staging examinations, three of 10 patients were upstaged by PET/CT. CONCLUSION: (18)F-FDG PET/CT diagnosis of primary lesions in EMPD is mainly dependent on the thickness of the lesions, whereas it is more sensitive for the diagnosis of metastases.

Adenocarcinoma with BAC features presented as the nonsolid nodule is prone to be false-negative on 18F-FDG PET/CT.

PURPOSE: The present study investigated which type of adenocarcinoma with BAC features was prone to be false-negative on 18F-FDG PET/CT. MATERIALS AND METHODS: A retrospective study was performed on 51 consecutive patients with localized adenocarcinoma with BAC features. CT and PET were assessed for lesion size, GGO percentage, and SUVmax. Lesions with FDG uptake the same as or more than mediastinal blood-pool activity were considered as PET-positive. RESULTS: Of the 51 cases, 19.6% presented as pure GGO nodules, 31.4% as mixed nodules, and 49.0% as solid nodules. None of the pure GGO nodules was 18F-FDG avid, compared with 37.5% of mixed nodules and 96.0% of solid nodules (χ2=31.55, P=0.000). In the mixed nodule group, SUVmax was negatively correlated with GGO percentage (r=-0.588; P=0.021). The positive detection rate of 18F-FDG PET/CT was 50.0%, 55.6%, and 100% in tumors 1.1-2.0 cm, 2.1-3.0 cm, and >3.0 cm in diameter, respectively (χ2=5.815, P=0.055). General linear model factor analysis showed that the GGO was an important factor contributing to false-negative PET/CT results (F=23.992, P=0.000), but lesion size was not (F=0.602, P=0.866). CONCLUSIONS: The present study indicated that the adenocarcinoma with BAC features presented as nonsolid nodule is prone to be false negative on 18F-FDG PET/CT.