F18-fluorodeoxyglucose positron emission tomography/computed tomography in the evaluation of vertebral vascular tumors

PurposeThe uptake of ¹⁸F-FDG is higher in most malignancies than in benign tumors. This study aimed to investigate the diagnostic value of ¹⁸F-FDG PET/CT in vertebral vascular tumors.Materials and methodsWe retrospectively collected PET/CT and clinical data of patients with vertebral vascular tumors and analyzed the location, number, and bone destruction and FDG uptake features of the lesion. We measured SUVmax and maximum diameter and analyzed the correlations between SUVmax and the pathological results, size, and CT features.ResultsTwenty-one pathology-proven vertebral vascular tumors were included: 2 angiosarcomas (SUVmax, 11.6 and 32.3), 1 epithelioid hemangioendothelioma (SUVmax, 5.7), 1 epithelioid hemangioma (SUVmax, 8.5), and 17 aggressive hemangiomas. Twelve cases of typical hemangiomas were included as controls. The SUVmax and diameter of the aggressive hemangiomas were higher than those of the typical hemangiomas. The mean SUVmax of aggressive hemangiomas with cortical destruction was higher than that of those without cortical destruction (t = −2.566, P = 0.022). Radioactive distribution in aggressive hemangiomas was homogeneous and heterogeneous in nine and eight cases, respectively. In six aggressive hemangiomas, the FDG uptake of residual and marginal sclerosing bone was higher than that of the osteolytic destruction area and/or paravertebral soft tissue. Six aggressive hemangiomas involved the spinal canal, without clear visualization on PET/CT.Conclusion¹⁸F-FDG uptake of vertebral malignant vascular tumors is higher than that of hemangiomas. The FDG uptake of hemangiomas varies and may be related to concurrent cortical destruction. ¹⁸F-FDG PET/CT shows limitations in evaluating the spinal canal involvement of aggressive hemangioma.     

Dual-time point PET/CT with F-18 FDG for the differentiation of malignant and benign bone lesions

Purpose  The purpose of the present study was to evaluate whether 2-fluoro[fluorine-18]-2-deoxy-d-glucose (F-18 FDG) positron emission tomography (PET) could differentiate malignant and benign bone lesions and whether obtaining delayed F-18 FDG PET images could improve the accuracy of the technique. Methods  In a prospective study, 67 patients with bone lesions detected by computed tomography (CT) or magnetic resonance imaging were included. Whole body PET/CT imaging was performed at 1 h (early) after the F-18 FDG injection and delayed imaging at 2 h post injection was performed only in the abnormal region. Semiquantitative analysis was performed using maximum standardized uptake value (SUV_max), obtained from early and delayed images (SUV_maxE and SUV_maxD, respectively). The retention index (RI) was calculated according to the equation: RI = (SUV_maxD − SUV_maxE) × 100/SUV_maxE. Histopathology of surgical specimens and follow-up data were used as reference criteria. The SUV_maxE and RI were compared between benign and malignant lesions. Results  The final diagnoses revealed 53 malignant bone lesions in 37 patients and 45 benign lesions in 30 patients. There were statistically significant differences in the SUV_maxE between the malignant and benign lesions (P = 0.03). The mean SUV_maxE was 6.8 ± 4.7 for malignant lesions and 4.5 ± 3.3 for benign lesions. However, a considerable overlap in the SUV_maxE was observed between some benign and malignant tumors. With a cutoff value of 2.5 for the SUV_maxE, the sensitivity, specificity, and accuracy were 96.0%, 44.0%, and 72.4%, respectively. The positive predictive value (PPV) and negative predictive value (NPV) were 67.1% and 90.9%, respectively. There were significant differences in the RI between the malignant and benign lesions (P = 0.004). But there was overlap between the two groups. The mean RI was 7 ± 11 for the benign lesions and 18 ± 11 for the malignant lesions. When an RI of 10 was used as the cutoff point, the sensitivity, specificity, and accuracy were 90.6%, 76.0%, and 83.7.0%, respectively. The PPV and NPV were 81.4% and 87.1%, respectively. Conclusions  The results of this study indicate that dual-time point F-18 FDG PET may provide more help in the differentiation of malignant tumors from benign ones.     

Malignant epithelioid hemangioendothelioma of the lower extremity: staging with F-18 FDG PET/CT

A 36-year-old woman presented with a 5-month history of a growing left thigh mass, causing difficulty walking. Biopsy revealed a malignant epithelioid hemangioendothelioma (EHE), and the patient was referred for a staging F-18 FDG PET/CT that showed intense FDG uptake in the thigh mass, but no FDG-avid local lymph nodes or distant metastases. A few reports have noted the usefulness of F-18 FDG PET/CT imaging in the staging of EHEs in the lung, liver, and bone marrow. This rare study highlights the usefulness of F-18 FDG PET/CT in the staging of malignant EHE of the soft tissues of the extremities.     

[<Superscript>18</Superscript>F]FDG PET/CT in the diagnosis of malignant peripheral nerve sheath tumours in neurofibromatosis type-1

Purpose  The detection of malignant peripheral nerve sheath tumours (MPNSTs) in patients with neurofibromatosis 1 (NF1) remains a clinical challenge. The purpose of this study was to evaluate the use of [¹⁸F]2-fluoro-2-deoxy-d-glucose PET/CT (FDG PET/CT with early and delayed imaging) in patients with symptomatic neurofibromas, to revalidate current cut-off values for identification of malignant change within neurofibromas and to examine the relationship between SUV and tumour grade. Methods  Patients with symptomatic neurofibromas underwent FDG PET/CT imaging at 90 and 240 min. Semiquantitative analysis using maximum standardized uptake value (SUVmax) was performed and correlated with histology. Result  In 69 patients, 85 lesions were identified for analysis, including 10 atypical neurofibromas and 21 MPNSTs. Sensitivity of FDG PET/CT in diagnosing NF1-associated MPNST was 0.97 (95% CI 0.81–0.99) and the specificity was 0.87 (CI 0.74–0.95). There was a significant difference in SUVmax between early and delayed imaging and in SUVmax between tumours identified as benign and malignant on PET/CT. There was also a significant difference in SUVmax between tumour grades. Conclusion  FDG PET/CT is a highly sensitive and specific imaging modality for the diagnosis of MPNST in NF1 patients. We recommend performing early (90 min) and delayed imaging at 4 h for accurate lesion characterization and using a cut-off SUVmax of 3.5 on delayed imaging to achieve maximal sensitivity.     

18 F-FDG PET/CT in diagnostic and prognostic evaluation of patients with cardiac masses: a retrospective study

Correct diagnosis and prognostic assessment of cardiac masses are crucial before therapy. We evaluated the diagnostic and prognostic value of 18F-FDG PET/CT in patients with cardiac masses. 18F-FDG PET/CT images of 64 patients with 65 cardiac masses were retrospectively analysed (34 men, 30 women; average age, 51.2 ± 17.5 years). Comparisons of CT features and 18F-FDG metabolic indices between benign and malignant entities, as well as among primary and secondary malignancies and lymphoma, were performed. The diagnostic values of PET/CT for distinguishing benign versus malignant masses were calculated. PET/CT data were further assessed for the predictive value for overall survival (OS) using the Cox proportional hazards model to assess potential independent predictors. Kaplan-Meier curves were generated to assess the value of PET/CT for prognostication. Statistically significant differences in various morphological features and metabolic indices between benign and malignant masses were found. An SUVmax of 6.75 was the optimal cutoff value to differentiate between benign and malignant masses, and the diagnostic sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were 92.11%, 88.89%, 90.77%, 92.11%, and 88.89%, respectively. Taking CT features and SUVmax ≥ 6.75 as a criterion, the values were 76.32%, 100.00%, 86.15%, 100.00%, and 75.00%, respectively; taking ≥ 3 CT features or SUVmax ≥ 6.75 as a criterion, the values were 94.74%, 88.89%, 92.31%, 92.31%, and 92.31%, respectively, indicating optimal diagnostic performance when paired with the anatomic information provided by the CT component. A univariate analysis of OS determined that surrounding tissue infiltration, epicardial infiltration, necrosis, multiple chambers or vessel involvement, distant metastasis, SUVmax, SUVmean, metabolic tumour volume (MTV), and total lesion glycolysis (TLG) were significant predictors of survival. In the multivariate analysis, only SUVmax ≥ 6.715 was significant (P < 0.01). Median OS was 1460 days for SUVmax < 6.715 and 342 days for SUVmax ≥ 6.715 (P < 0.01). 18F-FDG PET/CT is helpful in the diagnosis of cardiac masses before treatment and has value in detecting extracardiac primary or secondary tumours. 18F-FDG PET/CT could also be a promising tool to provide prognostic information for these patients, especially SUVmax displaying independent prognostic value.     

Role of 18F-FDG PET/CT in differentiation of a benign lesion and metastasis on the ribs of cancer patients

ObjectiveIncidental 18-Fluoro-2-deoxyglucose positron emission tomography (¹⁸F-FDG) uptake in the ribs is a relatively common finding on positron emission tomography/computed tomography (PET/CT) images of cancer patients. This study examined the role of ¹⁸F-FDG PET/CT in differentiating between benign lesions and metastases on the ribs.MethodsThis study included 264 lesions in 172 PET/CT cases with underlying malignancy showing newly developed indeterminate ¹⁸F-FDG rib uptake between June 2009 and May 2010. Patients with more than five FDG rib uptakes or hematologic malignancy were excluded. Malignancy was confirmed either histologically or by imaging studies, and clinical follow-up with serial images was at least 6 months. The maximum standardized uptake value (SUVmax) of the rib lesion was recorded. The FDG uptake patterns (focal or segmental; discrete or non-discrete) and CT findings (evidence of fracture, soft tissue lesions, osteoblastic and/or osteolytic lesions) were recorded.ResultsThere were 206 benign lesions and 58 metastases. The SUVmax was significantly higher in the metastatic group (3.0±1.8) than in the benign group (2.5±1.1), (P= .014). For the differential diagnosis between benign and metastatic lesions, the best SUVmax cut-off was determined to be 2.4. Significant indicators for metastasis were a segmental FDG uptake pattern (OR=10.262, 95% CI 4.151–25.371), presence of an osteoblastic/-lytic lesion (OR=22.903, 95% CI 10.468 to 50.108) and the absence of fractures on CT (OR=291.629, 95% CI 39.09–2175.666).ConclusionSUVmax alone is not sufficient to differentiate benign and metastatic rib lesions in cancer patients. The diagnostic accuracy can be further increased when findings of the CT part of PET/CT are considered.     

Prognostic utility of FDG PET/CT in advanced ovarian,fallopian and primary peritoneal high-grade serous cancer patients before and after neoadjuvant chemotherapy

In patients with advanced ovarian, fallopian and primary peritoneal carcinoma, complete interval debulking surgery (IDS) is often performed after neoadjuvant chemotherapy (NAC) to achieve long progression-free survival (PFS) and overall survival (OS). We aimed to investigate the utility of 2-deoxy-2-[F-18]fluoro-d-glucose (FDG) PET/CT in patients with these malignancies who underwent complete IDS. Between 2009 and 2017, twenty-two patients underwent FDG PET/CT scans before and after NAC. The highest SUVmax/peak (standardized uptake value), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) for whole lesions were defined as target SUVmax/peak, tMTV and tTLG, respectively. We also calculated these reduction rates during NAC. These parameters were compared between the groups with platinum-free interval (PFI) > 12 months (n = 10) and those with PFI ≤ 12 months (n = 12). The PFS and OS were evaluated using these quantitative parameters, and in terms of the presence of visually detectable residual lesions after NAC. The target SUVmax/peak before NAC, the reduction rates in the target SUVmax, tMTV and tTLG were significantly higher in the group with PFI > 12 months than the shorter PFI group (p < 0.05). Especially in PFS, the higher reduction rates in the target SUVmax/peak, tMTV, and tTLG had an excellent prognostic stratification (p < 0.05) and the FDG visually negative group after NAC had a significantly better prognosis than the other group (p < 0.01). The reduction rate of FDG PET-based quantitative values and visual analysis after NAC demonstrated prognostic potential, especially in PFS.     

Dual-time point 18F-FDG PET/CT scan for differentiation between 18F-FDG-avid non-small cell lung cancer and benign lesions

Objective  The aim of this study is to clarify the difference of F-18 FDG uptake kinetics between FDG-avid non-small-cell lung cancer (NSCLC) and benign lesions associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation. Materials and methods  The materials were 76 FDG-avid solitary NSCLC in 76 patients and 57 FDG-avid solitary benign lesions associated with various etiologies in 61 patients. FDG PET/CT scan was performed at 60 and 120 min after intravenous injection of 4.4 MBq/kg F-18 FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%ΔSUVmax) between the two time points were measured. The optimal differential parameter was determined by receiver-operating characteristic curve analysis and evaluation of diagnostic accuracy. Results  The mean ± SD of early SUV max, delayed SUVmax and %ΔSUVmax were 8.3 ± 5.2, and 10.2 ± 6.5, and 21.9% ± 18.9 in FDG-avid NSCLC, and 3.8 ± 3.2, 4.0 ± 3.7, and 11.3% ± 26.0 in FDG-avid benign lesions, respectively. Delayed SUVmax in NSCLC was significantly higher than early SUVmax (P < 0.0001); while not different in benign lesions. Percent change of SUVmax in NSCLC was also significantly higher than that in benign lesions (P < 0.01). The optimal parameter for the differentiation was delayed SUVmax > 5.5 and yielded sensitivity of 77.6%, specificity of 80.7% and accuracy of 78.9%, which provided better differentiation than the use of %ΔSUVmax or the traditional parameter of early SUVmax > 2.5. However, 11 (19.2%) benign lesions were indistinguishable from NSCLC. Conclusion  Although delayed PET/CT scan enhances the difference of FDG uptake between FDG-avid NSCLC and benign lesions, and the use of delayed SUVmax > 5.5 appears to improve the differentiation of these hypermetabolic lesions compared with an early scan, careful interpretation and management for correct differentiation are still required.     

^18F-FDG PET／CT显像全身骨髓代谢弥漫增高原因分析

目的分析^18F—FDG PET／CT所示全身骨髓代谢弥漫性增高临床原因。方法收集2005年8月至2009年11月期间在该院行^18F-FDG PET／CT检查,发现全身骨髓代谢弥漫性增高且已确诊的病例66例,分析影像学表现,并进行临床病程随访和病理结果分析。选择79名健康人作为对照组;分别测量骨髓代谢增高组和对照组的骨髓SUVmax和SUVmean以及纵隔SUVmax和SUVmean,并计算最大值比（SUVmax／纵隔SUVmax）及平均值比（骨髓SUVmean／纵隔SUVmean）,采用单因素方差分析对结果进行分析。结果（1）全身骨髓代谢弥漫l生增高原因有：近期升白细胞药物注射史27例,血液病21例,发热18例。（2）将上述3组及对照组SUVmean比（3．076±1．955,3．633±2．405,2．546±0．791,1．026±0．190）进行方差分析,F=34．465,P〈0．001,差异有统计学意义。健康对照组与3组骨髓代谢增高组进行多重比较,P均〈0．001,提示对照组与骨髓代谢增高组的SUVmean比差异均有统计学意义。（3）根据SUVmean比将骨髓代谢增高的程度分为2级：轻度（SUVmean比2．0—3．0）和重度（SUVmean大于3．0）。（4）3组骨髓代谢弥漫增高组中部分患者会伴有肝脾肿大及代谢增高,较常见的为血液病和发热。结论^18F-FDG PET／CT显像可以较敏感和准确地观察全身骨髓代谢的改变情况,良性和恶性病变均可引起骨髓代谢不同程度增高。     

F-18 FDG positron emission tomography and benign fractures

PURPOSE: F-18 2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) has been used extensively in the imaging of cancer, including metastatic skeletal disease. Although uptake into benign osseous disease has been reported, there is very limited information regarding uptake into benign fractures. This report provides additional information regarding the appearance of benign fractures on FDG-PET images. MATERIALS AND METHODS: Four case reports of FDG-PET scanning are presented in patients with proved benign fractures. RESULTS: In three of these cases, FDG uptake was noted in fractures when images were obtained 17 days to 8 weeks after injury, with the most avid uptake observed when FDG-PET imaging was performed 17 days after fracture. In the patient in whom imaging was performed 8 weeks after fracture, no uptake of FDG was seen in a benign fracture. CONCLUSIONS: Fractures may accumulate FDG to varying degrees, and false-positive findings may occur when FDG-PET imaging is performed to assess for metastases, although the different pattern of uptake and clinical correlation usually allows accurate differentiation of fracture from skeletal metastases.     

Benign Schwannoma Mimicking Metastatic Lesion on F-18 FDG PET/CT in Differentiated Thyroid Cancer

We report a case of benign schwannoma mimicking metastatic carcinoma. A 55-year-old female with papillary thyroid carcinoma underwent total thyroidectomy. F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) demonstrated a focal hypermetabolic lesion with maximum standardized uptake value (SUVmax) 5.3 at the right chest wall. Conventional chest CT demonstrated a 5.4 cm ovoid mass lesion between the intercostal muscles and liver. Pathology revealed a schwannoma by tumor excision. This case demonstrates that benign schwannoma may demonstrate FDG uptake mimicking metastatic carcinoma.     

The additional value of CT images interpretation in the differential diagnosis of benign vs. malignant primary bone lesions with 18F-FDG-PET/CT

Objective  To evaluate the value of a dedicated interpretation of the CT images in the differential diagnosis of benign vs. malignant primary bone lesions with 18fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG-PET/CT). Materials and methods  In 50 consecutive patients (21 women, 29 men, mean age 36.9, age range 11–72) with suspected primary bone neoplasm conventional radiographs and 18F-FDG-PET/CT were performed. Differentiation of benign and malignant lesions was separately performed on conventional radiographs, PET alone (PET), and PET/CT with specific evaluation of the CT part. Histology served as the standard of reference in 46 cases, clinical, and imaging follow-up in four cases. Results  According to the standard of reference, conventional 17 lesions were benign and 33 malignant. Sensitivity, specificity, and accuracy in assessment of malignancy was 85%, 65% and 78% for conventional radiographs, 85%, 35% and 68% for PET alone and 91%, 77% and 86% for combined PET/CT. Median SUV_max was 3.5 for benign lesions (range 1.6–8.0) and 5.7 (range 0.8–41.7) for malignant lesions. In eight patients with bone lesions with high FDG-uptake (SUV_max ≥ 2.5) dedicated CT interpretation led to the correct diagnosis of a benign lesion (three fibrous dysplasias, two osteomyelitis, one aneurysmatic bone cyst, one fibrous cortical defect, 1 phosphaturic mesenchymal tumor). In four patients with lesions with low FDG-uptake (SUV_max < 2.5) dedicated CT interpretation led to the correct diagnosis of a malignant lesion (three chondrosarcomas and one leiomyosarcoma). Combined PET/CT was significantly more accurate in the differentiation of benign and malignant lesions than PET alone (p = .039). There was no significant difference between PET/CT and conventional radiographs (p = .625). Conclusion  Dedicated interpretation of the CT part significantly improved the performance of FDG-PET/CT in differentiation of benign and malignant primary bone lesions compared to PET alone. PET/CT more commonly differentiated benign from malignant primary bone lesions compared with conventional radiographs, but this difference was not significant.     

F-18 FDG PET/CT findings in postradiation pelvic insufficiency fracture

We retrospectively identified eight patients who underwent F-18 FDG PET/CT and had diagnostic findings of postradiation pelvic insufficiency fracture. The fractures had a median SUV_max of 2.5 (range, 1.6 to 6.0) and were initially interpreted as possible metastases in six patients. A new bone lesion developing in the sacrum, pubic ramus, or acetabulum after radiation for pelvic malignancy is likely to be a postradiation pelvic insufficiency fracture, even if associated with increased FDG uptake at PET.     

Chemokine receptor-4 targeted PET/CT with 68 Ga-Pentixafor in assessment of newly diagnosed multiple myeloma: comparison to 18 F-FDG PET/CT

18F-FDG PET/CT has some limitations in the evaluation of multiple myeloma (MM). Since chemokine receptor-4 is overexpressed in MM, we perform a prospective cohort study to compare the performance of 68Ga-Pentixafor and 18F-FDG PET/CT in newly diagnosed MM. Thirty patients with newly diagnosed MM were recruited. All patients underwent 68Ga-Pentixafor and18F-FDG PET/CT within 1 week after enrollment. A positive PET/CT was defined as the presence of focal PET-positive lesions in bone marrow or diffuse bone marrow patterns (uptake > liver). Bone marrow uptake values in 68Ga-Pentixafor and18F-FDG PET/CT (total bone marrow glycolysis [TBmGFDG], total bone marrow uptake with 68Ga-Pentixafor [TBmUCXCR4], total bone marrow volume [TBmV], SUVmean, and SUVmax) were obtained by drawing total bone marrow volume of interest on PET/CT. The positive rates of the PET/CT scans were statistically compared, and the correlation between quantitative bone marrow uptake values and clinical characteristics, laboratory findings, and staging was analyzed. 68Ga-Pentixafor PET/CT had a higher positive rate than 18F-FDG PET/CT in recruited patients (93.3 vs. 53.3%, p = 0.0005). In quantitative analysis, bone marrow uptake values in 68Ga-Pentixafor (TBmUCXCR4, SUVmax, and SUVmean) were positively correlated with end organ damage, staging, and laboratory biomarkers related to tumor burden including serum β2-microglobulin, serum free light chain, and 24-h urine light chain (p < 0.05). In 18F-FDG PET/CT, only the SUVmean of total bone marrow was positively correlated with serum free light chain and 24-h urine light chain (p < 0.05). 68Ga-Pentixafor PET/CT is promising in assessment of newly diagnosed MM. NCT 03436342     

Focal F-18 FDG uptake mimicking malignant gastric localizations disappearing after water ingestion on PET/CT images

Diffuse, increased gastric wall F-18 FDG uptake is widely observed during PET/CT examinations, frequently unrelated to malignant findings, but simply caused by inflammatory disease, physiological emptying, or visceral thickening. Hence, elevated F-18 FDG gastric uptake can lead to equivocal misinterpretation, especially in patients with known gastric malignant disease, at posttherapy reevaluation. Gastric wall contraction can increase F-18 FDG uptake, especially for a remnant stomach, increasing the percentage of false-positive results with a direct impact on therapeutic management. One field PET/CT acquisition centered on the hypochondrial regions a few minutes after water ingestion should be performed routinely if standard images are doubtful (increased tracer uptake and visceral thickening) to differentiate benign from malignant uptake.     

Hepatic adenomatosis may mimic metastatic lesions of liver with 18F-FDG PET/CT

Hepatic adenomatosis is an uncommon benign neoplasm, with the presence of multiple adenomas (generally more than 4) within the liver. A 52-year-old woman presented with multiple (>10) solid liver lesions detected with abdominal ultrasonography and verified with magnetic resonance imaging (MRI). Subsequently, F-18 FDG PET/CT demonstrated increased uptake in these lesions. Histology revealed hepatic adenomatosis. F-18 FDG PET/CT cannot reliably differentiate hepatic adenomas from malignant processes on the basis of uptake.     

18F-FDG PET/CT显像诊断心包恶性病变的价值

目的 评价18F-脱氧葡萄糖（FDG）PET/CT对心包恶性病变的诊断价值.方法 对23例心包积液患者进行18F-FDG PET/CT显像,并采用两独立样本非参数检验分析良恶性病灶最大标准摄取值（SUVmax）差异有无统计学意义.结果 经病理检查证实恶性心包积液14例,良性心包积液9例.1例PET/CT假阴性,2例PET/CT假阳性.18F-FDG PET/CT鉴别诊断良恶性心包积液的灵敏度、特异性、准确性、阳性预测值、阴性预测值分别为92.9%（13/14）、7/9、87.0%（20/23）、86.7%（13/15）和7/8.良、恶性病变的SUVmax中位值分别为2.2和6.0,两者间比较差异有统计学意义（z=-3.279,P=0.001）.结论 18F-FDG PET/CT是评价心包恶性病变较好的无创性手段,对良恶性心包积液的诊断与鉴别诊断有一定临床价值.     

The Clinical Usefulness of 18F-FDG PET/CT in Patients with Systemic Autoimmune Disease

Purpose

Individuals with systemic autoimmune disease have an increased susceptibility to both inflammation and malignancy. The aim of this study was to evaluate the clinical usefulness of ¹⁸F-FDG PET/CT in patients with systemic autoimmune disease.

Methods

Forty patients diagnosed with systemic autoimmune disease were enrolled. Diagnostic accuracy of FDG PET/CT for detecting malignancy was assessed. FDG PET/CT findings, including maximum standardized uptake (SUVmax) of lymphadenopathy (LAP), liver, bone marrow, spleen, joint and muscles, were considered for the characterization of LAPs.

Results

FDG PET/CT could detect metabolically activated lesions in 36 out of 40 patients (90%) including inflammatory lesions in 28 out of 32 patients (88%). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG PET/CT for the detection of malignancy were 100, 67, 70, 25, and 100%, respectively. Multiple LAPs were found in 25 of 40 patients (63%), and comprised three malignancies, four cases of tuberculosis, and 18 reactive changes. A SUVmax ratio of bone marrow to liver below 0.78 could distinguish malignancy from tuberculosis + reactive change (AUC = 1.000, sensitivity: 100%, specificity: 100%). The SUVmax ratio of spleen to liver in the reactive group was also significantly higher than that in the malignancy group (P = 0.014). SUVmax of LAP in the TB group was significantly higher than that in the reactive group (P = 0.040).

Conclusions

PET/CT is useful in detecting and differentiating inflammation and malignancy in patients with systemic autoimmune disease. Frequent false-positive interpretations can be minimized by consideration of FDG uptake in bone marrow and spleen.     

Impact of FDG PET on the preoperative staging of newly diagnosed breast cancer

Purpose The main objective of this study was to determine the efficacy of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) to assess the impact of this technique in staging of patients with newly diagnosed breast cancer. Methods Two hundred and seventy-one consecutive patients (median age = 51 ± 11 years) with biopsy-proven primary breast cancer who were examined by FDG PET were enrolled in this prospective preoperative staging study. Whole-body FDG-PET images were acquired approximately 60 min after the intravenous administration of FDG (5.2 MBq/kg). Visual assessment and the maximum standardized uptake value (SUVmax) of breast lesions for semiquantitative analysis were carried out. The PET results were compared with the histopathology results. Results For the tumor, node, metastases (TNM) staging, 240 patients (250 breasts) were considered eligible based on the criteria that were established for this analysis. Significant differences were noted in SUVmax of lesions according to the TNM staging (p < 0.05). The average SUVmax of the primary tumor was calculated in patients with axillary involvement (n = 58) and for the ones without axillary metastasis (n = 79), and SUVmax were 4.1 ± 3.5 and 2.8 ± 2.3, respectively, with a significant difference between the two groups (p = 0.03). PET imaging revealed pathological FDG uptake in 54% (46/85) of patients with axillary lymph node metastases. The sensitivities of FDG PET for detecting axillary lymph node metastasis were found 41% in pN1, 67% in pN2, and 100% in pN3, and the specificity was 89% for pN0 stage. Detection of extra-axillary regional node or distant metastatic lesions revealed by PET scan in 22 of 24 patients resulted in a significant change in the TNM stage. Distant metastasis without axillary lymph node metastasis was noted in 21% (5/24) of patients. The results revealed that FDG PET upgraded TNM stage in 9.2% (22/240) of patients and 7.5% (18/240) of patients were diagnosed as having one or more distant metastases. Conclusion FDG PET was able to identify extra-axillary regional nodal and distant lesions in newly diagnosed patients with breast cancer; FDG PET may alter the staging and management of therapy in patients with newly diagnosed breast cancer.     

Dual-time-point F-18 FDG PET/CT imaging for differentiating the lymph nodes between malignant lymphoma and benign lesions

Purpose

The purpose of the present study is to evaluate the clinical value of dual-time-point F-18 FDG PET/CT imaging to differentiate malignant lymphoma (ML) from benign lymph node (BLN).

Materials and methods

The subjects were 310 lymph nodes in 84 patients (195 ML lesions in 30 patients and 115 BLN in 54 patients associated with various etiologies.). F-18 FDG PET/CT scan was performed at 50 min (early scan) and at 100 min (delayed scan) after the injection. First, the maximum standardized uptake value (SUVmax) of each lesion at early and delayed scans was calculated. Second, we estimated the difference between early and delayed SUVmax (D-SUVmax) and the retention index (RI-SUVmax) to evaluate the change of tracers in the lesions. Furthermore, proper cut-off values of them were evaluated using receiver operating characteristic analysis. The efficacy of each parameter was analyzed with ANOVA.

Results

Delayed SUVmax and D-SUVmax in ML were significantly higher than those in BLN. Proper cut-off value in delayed SUVmax was 4.0 and in D-SUVmax was 1.0. When the proper cut-off value in D-SUVmax was applied, the D-SUVmax yielded the role of diagnosis with sensitivity of 82.6 %, specificity of 65.2 %, positive predictive value of 80.1 % and negative predictive value of 68.8 %, respectively.

Conclusions

The delayed SUVmax and D-SUVmax were useful indices to differentiate ML from BLN, regardless of histologic subtype. Dual-time-point F-18 FDG PET/CT imaging may help to consider whether there is any need to proceed to more invasive tests, such as biopsy, in individual patients.