Lung Adenocarcinoma Staged as an Unknown Primary Presenting with Symptomatic Colon Metastases: Staging by 18F-FDG PET/CT

A 66-year-old man, who presented with bright red blood per rectum, was referred for an ¹⁸F-FDG PET/CT after colonoscopy showed two suspicious colon masses, which were biopsied to reveal an adenocarcinoma of unknown origin. PET/CT showed two intensely FDG-avid colon masses as well as an unsuspected FDG-avid lung mass, which was biopsied to reveal a primary lung adenocarcinoma. Immunohistochemistry confirmed the two colon metastases were of pulmonary origin. It is extremely rare for lung carcinoma to present with symptomatic colon metastases, with only 11 cases described in the literature. We report the first case of the utility of ¹⁸F-FDG PET/CT in staging a patient who presented with symptomatic colon metastases of an unknown primary lung malignancy.     

Primary Pulmonary Low-Grade Angiosarcoma Characterized by Mismatch between 18F-FDG PET and Dynamic Contrast-Enhanced CT

We report a rare case of primary pulmonary low-grade angiosarcoma on dynamic contrast-enhanced CT and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT imaging. A 38-year-old, asymptomatic woman was hospitalized because of an abnormality on chest radiography. A dynamic contrast-enhanced chest CT showed a 1.2 cm-sized irregular-margined nodule with strong and persistent enhancement in the right lower lobe. The lesion had low metabolic activity on an ¹⁸F-FDG PET/CT scan. The patient underwent a wedge resection for the lesion, and pathology revealed a primary pulmonary low-grade angiosarcoma.     

18F-FDG PET/CT bone/bone marrow findings in Hodgkin’s lymphoma may circumvent the use of bone marrow trephine biopsy at diagnosis staging

Purpose

Accurate staging of Hodgkin’s lymphoma (HL) is necessary in selecting appropriate treatment. Bone marrow trephine biopsy (BMB) is the standard procedure for depicting bone marrow involvement. BMB is invasive and explores a limited part of the bone marrow. ¹⁸F-FDG PET/CT is now widely used for assessing response to therapy in HL and a baseline study is obtained to improve accuracy. The aim of this retrospective analysis was to assess whether routine BMB remains necessary with concomitant ¹⁸F-FDG PET/CT.

Methods

Data from 83 patients (newly diagnosed HL) were reviewed. All patients had received contrast-enhanced CT, BMB and ¹⁸F-FDG PET/CT. Results of BMB were not available at the time of ¹⁸F-FDG PET/CT imaging.

Results

Seven patients had lymphomatous involvement on BMB. Four patients had bone involvement on conventional CT (two with negative BMB). All patients with bone marrow and/or bone lesions at conventional staging were also diagnosed on ¹⁸F-FDG PET/CT scan. PET/CT depicted FDG-avid bone/bone marrow foci in nine additional patients. Four of them had only one or two foci, while the other had multiple foci. However, the iliac crest, site of the BMB, was not involved on ¹⁸F-FDG PET/CT. Osteolytic/sclerotic lesions matching FDG-avid foci were visible on the CT part of PET/CT in three patients. MRI ordered in three other patients suggested bone marrow involvement. Interim and/or end-therapy ¹⁸F-FDG PET/CT documented response of FDG-avid bone/bone marrow foci to chemotherapy in every patient.

Conclusion

¹⁸F-FDG PET/CT highly improves sensitivity for diagnosis of bone/bone marrow lesions in HL compared to conventional staging.     

Usefulness of 18F-FDG PET/CT for the Evaluation of Bone Marrow Involvement in Patients with High-Grade Non-Hodgkin’s Lymphoma

Purpose

To assess the usefulness of ¹⁸F-fluorodeoxyglucose PET/CT in the detection of bone marrow (BM) involvement of high-grade non-Hodgkin’s lymphoma (NHL).

Methods

One hundred twenty patients with newly diagnosed diffuse large B-cell lymphoma or peripheral T-cell lymphoma between January 2007 and June 2011, who received BM trephine biopsy and ¹⁸F-FDG PET/CT before chemotherapy, were included in this retrospective study. We reviewed their ¹⁸F-FDG PET/CT images and bone marrow biopsy (BMB) results. After reviewing the images, we reviewed the medical records and radiological findings of interesting patients.

Results

There were 23 ¹⁸F-FDG PET/CT scans in which the marrow was considered to be abnormal (either positive or equivocal), and 97 ¹⁸F-FDG PET/CT scans were regarded as having negative FDG uptake. Of 120 patients, 100 (83.3 %) had a concordant result of BM interpretation between ¹⁸F-FDG PET/CT and BMB, and the remaining 20 patients had discordant results. Among 23 patients with either positive or equivocal ¹⁸F-FDG PET/CT scans, 1 of 12 patients with ‘positive’ ¹⁸F-FDG PET/CT had a lymphomatous involvement on BMB. In contrast, 10 of 11 patients with ‘equivocal’ BM hypermetabolism were reported as having positive involvement by BMB. Patients with abnormal ¹⁸F-FDG PET/CT had significantly higher mSUV_highest than those with normal FDG-PET/CT.

Conclusions

¹⁸F-FDG PET/CT and BMB are complementary techniques in assessing the presence of BM involvement in patients with high-grade NHL. The increasing availability of ¹⁸F-FDG PET/CT will raise the need for additional biopsy for FDG-avid lesions, especially in patients with negative standard BMBs. ¹⁸F-FDG PET/CT can be useful as a decision-making tool for determining whether to perform a standard BMB or targeted biopsy to the FDG-avid lesion as an initial staging procedure. A direct bone biopsy for FDGpositive bone lesions should be included in staging guidelines in future. In ¹⁸F-FDG PET/CT-negative cases, BMB is still a powerful procedure, but BMB alone is insufficient for full evaluation of BM.     

Necrotizing Cervical Lymphadenitis Caused by Mycobacterium simiae in an HIV-Positive Patient: Imaging with 18F-FDG PET/CT

Mycobacterium simiae (M. simiae) is an opportunistic pathogen rarely associated with human disease, although in recent years M. simiae has been detected with increasing frequency in human immunodeficiency virus (HIV)-infected patients, usually causing disseminated infection with fever, diarrhea and weight loss. We report the case of an HIV-positive man, who was referred for an ¹⁸F-FDG PET/CT to evaluate a solitary pulmonary nodule. The PET/CT showed incidental large necrotic cervical lymph nodes, compatible with necrotizing cervical lymphadenitis. Biopsy and culture of one of the affected lymph nodes were positive for M. simiae. We present the first report of ¹⁸F-FDG PET/CT imaging of an infectious process caused by M. simiae in humans.     

18F-FDG PET/CT显像联合HRCT对孤立性原发肺浸润性黏液腺癌的诊断价值

目的探讨孤立性原发肺浸润性黏液腺癌18F-FDG PET/CT显像和HRCT征象及两者联合对该病的诊断价值。方法回顾性分析经病理证实为浸润性黏液腺癌、有18F-FDG PET/CT双时相显像及病灶层面同机HRCT扫描资料的9例患者,对PET/CT早期、延迟显像及滞留指数、HRCT征象进行综合分析。结果HRCT图像上表现为2例呈实性结节、病灶周围无类似卫星灶样影,6例实性结节周围伴小点片及磨玻璃样影,1例为单纯磨玻璃样结节;分叶征(6例)、血管集束征(6例)、支气管充气征(4例)、空泡征(2例)、毛刺征(1例);18F-FDG PET/CT融合图像上8例病灶表现为不均匀FDG代谢增高,早期显像平均SUVmax为3.2±2.5,延迟现象SUVmax增高6例、降低2例,平均SUVmax为3.5±2.4,平均滞留指数为(10.4±29.3)%,9例均未见纵隔、双侧肺门淋巴结及其他部位转移征象,其18F-FDG PET/CT融合图像上18F-FDG摄取与HRCT相匹配,18F-FDG摄取相对集中于结节的实性区域,病灶磨玻璃区18F-FDG摄取不明显;综合手术病理结果等临床资料证实,9例均为T1N0M0期,与PET/CT分期一致。结论对于影像学检查发现肺孤立性占位患者,在单一影像学检查难以明确诊断的情况下,18F-FDG PET/CT双时相显像上病灶不均匀18F-FDG摄取相对集中于其实性区域的代谢方式与HRCT相联合,可辅助孤立性原发性肺浸润性黏液腺癌的诊断。     

Steroid responsive inflammatory myofibroblastic tumor of the lung evaluated by FDG PET/CT imaging

A 68-year-old gentleman was referred for ¹⁸F-FDG PET/CT for a pulmonary mass in the left upper lobe which demonstrated intensely FDG-avid confluent pulmonary consolidation in the left upper lobe (SUV_max 15.1). Histopathologic biopsy of the left upper lobe lung mass was consistent with inflammatory myofibroblastic tumor (IMT). The patient was started on steroid treatment in conjunction with antibiotics. Follow-up FDG PET/CT 3 weeks after commence of treatment showed remarkable response of the IMTs to therapy with much less avid FDG uptake (SUV_max 5.4) and marked improvement in the pulmonary consolidation. Nevertheless, the patient underwent left upper lobe lobectomy due to evidence of persistent cystic disease and malignant potential associated with IMTs. Final histopathology was consistent with IMT with no evidence of malignancy.     

Giant Cell Tumor with Secondary Aneurysmal Bone Cyst Shows Heterogeneous Metabolic Pattern on <Superscript>18</Superscript>F-FDG PET/CT: A Case Report

Giant cell tumor (GCT) is a generally benign bone tumor accounting for approximately 5 % of all primary bone neoplasms. Cystic components in GCTs that indicate secondary aneurysmal bone cysts (ABCs) are reported in 14 % of GCTs. Although both of them have been described separately in previous reports that may show considerable fluorodeoxyglucose (FDG) uptake despite their benign nature, the findings of GCT with secondary ABC on ¹⁸F-FDG positron emission tomography/computed tomography (PET/CT) have not been well-known. We report a case of GCT with secondary ABC in a 26-year-old woman. ¹⁸F-FDG PET/CT revealed a heterogeneous hypermetabolic lesion in the left proximal femur with the maximum standardized uptake value of 4.7. The solid components of the tumor showed higher FDG uptake than the cystic components. These observations suggest that the ABC components in GCTs show heterogeneous metabolic patterns on ¹⁸F-FDG PET/CT.     

Risk-related <Superscript>18</Superscript>F-FDG PET/CT and new diagnostic strategies in patients with solitary pulmonary nodule: the ITALIAN multicenter trial

Purpose

Diagnosis of solitary pulmonary nodule (SPN) is an important public health issue and ¹⁸F-FDG PET/CT has proven to be more effective than CT alone. Pre-test risk stratification and clinical presentation of SPN could affect the diagnostic strategy. A relevant issue is whether thoracic segmental (s)-PET/CT could be implemented in patients with SPN. This retrospective multicenter study compared the results of FDG whole-body (wb)-PET/CT to those of s-PET/CT.

Methods

¹⁸F-FDG PET/CT of 502 patients, stratified for pre-test cancer risk, were retrospectively analyzed. The thoracic part of wb-PET/CT, considered s-PET/CT, was compared to wb-PET/CT. Clinical and PET/CT variables were investigated for SPN characterization as well as for identification of patients in whom s-PET/CT could be performed. Histopathology or follow-up data were used as a reference.

Results

In the study population, 36% had malignant, 35% benign, and 29% indeterminate SPN. ¹⁸F-FDG uptake indicative of thoracic and extra-thoracic lesions was detectable in 13% and 3% of the patients. All patients with extra-thoracic metastases (n?=?13) had thoracic lymph node involvement and highest ¹⁸F-FDG uptake at level of SPN (negative predictive value 100%). Compared to wb-PET/CT, s-PET/CT could save about 2/3 of ¹⁸F-FDG dose, radiation exposure or scan-time, without affecting the clinical impact of PET/CT.

Conclusion

Pre-test probability of malignancy can guide the diagnostic strategy of ¹⁸FDG-PET/CT in patients with SPN. In subjects with low-intermediate pretest probability s-PET/CT imaging might be planned in advance, while in those at high risk and with thoracic lymph node involvement a wb-PET/CT is necessary.

     

~(18)F-FDG PET-CT和双源CT的LungCare软件在评估孤立性肺结节中的比较研究

目的 探讨18-氟-脱氧葡萄糖(~(18)F-FDG)PET/CT显像及Siemens双源CT的LungCare软件对孤立性肺结节(SPN)的辅助诊断能力及适用范围.方法 回顾分析经病理证实的24例SPN患者的PET-CT图像资料,并与利用双源CT的LungCare软件分析SPN进行比较研究.用χ~2检验对2种检查方法的评价结果进行统计学分析,以P<0.05作为差异有显著意义.结果 在24例SPN中,恶性结节15例,良性结节9例.LungCare软件评估其良恶性的准确性、敏感性、特异性、阳性预测值、阴性预测值分别为83.3%、80.0%、88.8%、92.3%、72.7%,PET-CT评估其良恶性的准确性、敏感性、特异性、阳性预测值、阴性预测值分别为87.5%、93.3%、77.7%,87.5%、87.5%.LungCare软件和PET/CT定性SPN的准确性相当,两者之间并不存在明显的差异(P>0.05).PET/CT的敏感性、阴性预测值明显高于LungCare软件,但其特异性、阳性预测值明显低于LungCare软件(P<0.05).结论 ~(18)F-FDG PET-CT对肺结节的诊断有一定辅助作用,适用于对孤立性肺结节的良恶性鉴别诊断.PET/CT密切结合LungCare软件,可进一步提高诊断正确率.     

Role of <Superscript>18</Superscript>F-FDG PET/CT in patients affected by Langerhans cell histiocytosis

Purpose

Langerhans cell histiocytosis (LCH) is a rare hematological disorder for which the utility of¹⁸F-FDG PET/CT is unclear. Our aim was to explore the metabolic features of LCH and the possible role of¹⁸F-FDG PET/CT in LCH evaluation.

Materials and methods

We found 17 patients with histologically proven LCH who underwent 17¹⁸F-FDG PET/CT scans for staging and 42 scans for restaging/follow-up purposes. PET/CT results were compared with those obtained from other conventional imaging modalities (bone scintigraphy, plain radiogram, computed tomography, magnetic resonance).

Results

¹⁸F-FDG PET/CT was positive in 15/17 patients, and it detected 36/37 lesions; all bone and extraskeletal lesions, except for a cecal lesion, were¹⁸F-FDG-avid. Only 1/4 of the patients with lung LCH had hypermetabolic lesions. The average SUV_max of the FDG-avid lesions was 7.3 ± 6.7, the average lesion-to-liver SUV_max ratio was 3.4 ± 2.5, and the average lesion-to-blood pool SUV_max ratio was 4 ± 3.2. In comparison to other imaging methods,¹⁸F-FDG PET/CT detected additional lesions or was able to evaluate treatment response earlier in 33/74 cases; it was confirmatory in 38/74 and detected fewer lesions in 3/74 (all three with lung LCH).

Conclusions

¹⁸F-FDG PET/CT seems to be useful for evaluating LCH when compared to conventional imaging, except in pulmonary cases. It can be used both for staging and restaging purposes.

     

Dual-time-point <Superscript>18</Superscript>F-FDG PET/CT in the diagnosis of solitary pulmonary lesions in a region with endemic granulomatous diseases

Objective

Granulomatous diseases (GDs) can be metabolically active and indistinguishable from lung cancer on ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) imaging. Evaluation of solitary pulmonary lesions remains a diagnostic challenge in regions with endemic GD. This study sought to determine the efficacy of dual-time-point (DTP) ¹⁸F-FDG PET/computed tomography (CT) imaging in diagnosing solitary pulmonary lesions from such regions.

Methods

A total of 50 patients with solitary pulmonary nodules or masses with confirmed histopathological diagnoses underwent DTP ¹⁸F-FDG PET/CT imaging at 1 and 3 h after tracer injection. The maximum standardized uptake value (SUV_max) on early and delayed scans (SUV_1h and SUV_3h, respectively) and retention index (RI) were calculated for each pulmonary lesion. Receiver operating characteristic analysis was performed to evaluate the discriminating validity of the parameters.

Results

There were 37 malignant and 13 benign solitary pulmonary lesions. Eight of the 13 (62 %) benign lesions were GDs. The sensitivity/specificity/accuracy of SUV_1h, SUV_3h and RI were 84/69/80 %, 84/85/84 %, and 81/54/74 %, respectively. SUV_3h had the best diagnostic performance, especially regarding specificity. The values of SUV_1h and SUV_3h were significantly different between malignant lesions and GD, while the RI values of malignant lesions and GD were both high (18.6 ± 19.5 and 18.7 ± 15.3 %, respectively; P = not significant).

Conclusion

SUV_3h appeared to improve the diagnostic specificity of ¹⁸F-FDG PET/CT in evaluating solitary pulmonary lesions from regions with endemic GD.

     

Diagnostic and prognostic value of 18F-FDG PET/CT in recurrent germinal tumor carcinoma

Aim

The aim of this bicentric retrospective study was to assess the diagnostic performance, the prognostic value, the incremental prognostic value and the impact on therapeutic management of ¹⁸F-FDG PET/CT in patients with suspected recurrent germinal cell testicular carcinoma (GCT).

Materials and methods

From the databases of two centers including 31,500 ¹⁸F-FDG PET/CT oncological studies, 114 patients affected by GCT were evaluated in a retrospective study. All 114 patients underwent ¹⁸F-FDG PET/CT for suspected recurrent disease. Diagnostic performance of visually interpreted ¹⁸F-FDG PET/CT and potential impact on the treatment decision were assessed using histology (17 patients), other diagnostic imaging modalities (i.e., contrast enhanced CT in 89 patients and MRI in 15) and clinical follow-up (114 patients) as reference. Progression-free survival (PFS) and overall survival (OS) rates were computed by means of Kaplan-Meier survival analysis. The progression rate (Hazard Ratio-HR) was determined using univariate Cox regression analysis by considering various clinical variables.

Results

Recurrent GCT was confirmed in 47 of 52 patients with pathological ¹⁸F-FDG PET/CT findings, by means of histology in 18 patients and by other diagnostic imaging modalities/follow-up in 29. Sensitivity, specificity, accuracy, positive and negative likelihood ratio (LR+ and LR-, respectively), pre-test Odds-ratio and post-test Odds-ratio of ¹⁸FDG PET/CT were 86.8%, 90.2%, 88.4%, 8.85, 0.14, 0.85, 8.85, respectively.¹⁸F-FDG PET/CT impacted significantly on therapeutic management in 26/114 (23%) cases (from palliative to curative in 12 patients, from “wait and watch” to new chemotherapy in six patients and the “wait-and-watch” approach in eight patients with unremarkable findings). At 2 and 5-year follow-up, PFS was significantly longer in patients with a negative than a pathological ¹⁸F-FDG PET/CT scan (98% and 95% vs 48% and 38%, respectively; p = 0.02). An unremarkable scan was associated also with a longer OS (98% after 2 years and 95% after 5 years, p = 0.02). At univariate Cox regression analysis, a pathological ¹⁸F-FDG PET/CT scan was associated with an increased risk of disease progression (HR = 24.3, CI 95% 14.1-40.6; p = 0.03) and lower OS (HR = 17.3 CI 95% 4,9-77; p < 0.001). Its prognostic value was confirmed also if tested against advanced disease at diagnosis and rising Human Chorionic Gonadotropin Beta (HCGB) or Alpha-Fetoprotein (AFP) (HR = 7.3 for STAGE III-PET+, p = 0.03; HR = 14.3 elevated HCGB-PET+, p = 0.02; HR 10.7 elevated AFP-PET+, p = 0.01) At multivariate analysis, only a pathological ¹⁸F-FDG PET/CT scan and advanced disease in terms of TNM staging were predictors of disease progression and OS. ¹⁸F-FDG PET/CT showed incremental value over other variables both in predicting PFS (chi-square from 24 to 40, p < 0.001) and OS (chi-square from 32 to 38, p = 0.003).

Conclusion

¹⁸F-FDG PET/CT has a very good diagnostic performance in patients with suspected recurrent GCT and has an important prognostic value in assessing the rate of PFS and OS. Furthermore, ¹⁸F-FDG PET/CT impacted the therapeutic regimen in 23% of patients, thus providing a significant impact in the restaging process.

     

Langerhans’ Cell Histiocytosis Masquerading as Metastatic Papillary Thyroid Cancer on F-18 FDG PET/CT: Diagnostic Dilemma Solved by PET/CT-Guided Biopsy

We present a case of papillary thyroid cancer (post-thyroidectomy status) on regular treatment with suppressive Levothyroxine therapy. On follow-up at 6 months after radioactive iodine ablation for remnant thyroid tissue, her thyroglobulin, and anti-thyroglobulin levels were 0.06 ng/ml and 670 IU/ml, respectively. Low-dose whole-body I-131 scan was negative. To look for the cause of isolated increased anti-thyroglobulin level, a whole-body ¹⁸F-FDG PET/CT was done which revealed multiple FDG-avid lytic skeletal lesions suggestive of metastases. For confirmation of diagnosis, ¹⁸F-FDG PET/CT-guided metabolic biopsy was done, which revealed Langerhans’ cell histiocytosis on histopathological examination.     

Clinical significance of small pulmonary nodules with little or no 18F-FDG uptake on PET/CT images of patients with nonthoracic malignancies.

Small pulmonary nodules with little or no perceptible (18)F-FDG uptake are relatively common findings on combined PET/CT images of patients with nonthoracic malignancies. Interpreting such nodules is often a diagnostic challenge, and this study aimed to evaluate the clinical significance of the nodules. METHODS: Patients with pulmonary nodules < or =1 cm in diameter showing no (18)F-FDG uptake or uptake less than the mediastinal background were included. Nodules with clearly benign or metastatic findings on CT were excluded. One hundred twenty-one patients had either tissue confirmation or clinical follow-up with additional chest images. The subjects were studied by 3 variables: (i) solitary versus multiple nodules, (ii) presence of accompanying benign lung lesion versus absence, and (iii) imperceptible (18)F-FDG uptake versus faint (18)F-FDG uptake. The malignancy rates were calculated for each variable. RESULTS: Of the 121 patients, 24 had malignancy, with a strong possibility of pulmonary metastasis (19.8%). Six of the 44 patients with solitary nodules (13.6%) and 18 of the 77 patients with multiple nodules (23.4%) had malignancies, though there was no statistically significant difference in the incidences of malignancy between the solitary and multiple groups. On the other hand, there was a statistically significant difference (P = 0.040) between the accompanying lung lesion present (8.3%) and absent (24.7%) groups. No statistically significant difference was noted between the (18)F-FDG uptake imperceptible group and faint (18)F-FDG uptake group (20.7% vs. 17.2%). CONCLUSION: For patients with incidental lung nodules of indeterminate nature with no (18)F-FDG uptake or uptake less than that of the mediastinum on PET/CT images, >19% of the cases turned out to be malignant. The nodule was more likely to be malignant when no other benign pulmonary lesions could be identified elsewhere in the lung field. Thus, regardless of the number of nodules and (18)F-FDG uptake, tissue confirmation or close imaging follow-up is necessary when small nodules with imperceptible or faint (18)F-FDG activity are present on the PET/CT images, especially in the absence of accompanying benign lung lesions.     

Primary Pulmonary Lymphoepithelioma-like Carcinoma on FDG PET/CT

A 69-year-old male smoker was referred to ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) with the indication of a suspicious solitary pulmonary nodule. FDG PET/CT determined a 2.5?×?2-cm soft-tissue lesion (SUVmax, 16.2) with spiculated margins in the hilum of the right lung. A 1-cm diameter lymphadenopathy on the right hilum with an SUVmax of 3.2 was also determined. Transbronchial biopsy of the right hilar lymphadenopathy did not reveal any malignant features in histopathologic examination, and it was determined to be reactive. The patient underwent a right upper lobe segmentectomy, and the histopathologic evaluation revealed that the tumor was a primary lymphoepithelioma-like carcinoma (LELC) of the lung with negative Epstein-Barr virus (EBV) on in situ hybridization studies. In this case report, we mainly focus on the FDG avidity of this very rare kind of tumor comparatively with previous reports and possible explanations of discordancy in FDG avidity in relation to histopathologic characteristics.     

Is <Superscript>18</Superscript>F-FDG PET/CT useful for the differential diagnosis of solitary pulmonary nodules in patients with idiopathic pulmonary fibrosis?

Objective

Idiopathic pulmonary fibrosis (IPF) is associated with an increased incidence of lung cancer, but patients with IPF often have poor pulmonary function and are vulnerable to pneumothorax and so using an invasive procedure to diagnose a single nodule detected on chest CT risks a critical adverse outcome. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is recognized to be useful for differentiating between benign and malignant solitary pulmonary nodules (SPN) in patients without IPF, but its diagnostic accuracy has not been investigated in patients with IPF. In this study, therefore, we investigated whether ¹⁸F-FDG PET/CT is useful for the differential diagnosis of SPNs in patients with IPF.

Methods

From the IPF patient cohort of our institution, we retrospectively reviewed 55 patients (54 men, 1 woman; age 67.8?±?7.6 years) with an SPN sized 8–30 mm (mean 18.5?±?5.7 mm) who underwent chest CT followed by ¹⁸F-FDG PET/CT between April 2004 and March 2016. The ¹⁸F-FDG uptake of the SPN was analyzed visually and semiquantitatively, and these determinations were compared with the final diagnosis obtained by pathology (n?=?52) or imaging follow-up (n?=?3).

Results

The final diagnoses showed that 41 (75%) of the SPNs were malignant (21 squamous cell carcinomas, 9 adenocarcinomas, 5 small-cell carcinomas, 4 mixed-type carcinomas, 1 large-cell neuroendocrine carcinoma, and 1 sarcoid carcinoma) and 14 (25%) were benign. The determination of malignant SPNs by visual analysis of the PET/CT images had a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 98, 86, 95, and 92%, respectively. The semiquantitative analysis using a maximum standardized uptake value of 2.0 as the cut-off had a sensitivity, specificity, PPV, and NPV of 95, 93, 98, and 87%, respectively.

Conclusions

¹⁸F-FDG PET/CT is useful for differentiating benign and malignant SPNs in patients with IPF, as it is for patients without IPF.

     

Role of 68Ga-DOTATOC PET/CT in initial evaluation of patients with suspected bronchopulmonary carcinoid

Purpose

The objective of this study was to evaluate the role of ⁶⁸Ga-DOTATOC positron emission tomography (PET)/CT scan in patients with suspected pulmonary carcinoid tumour and to compare its results with ¹⁸F-fluorodeoxyglucose (FDG) PET/CT scan.

Methods

In this prospective study, 32 patients (age 34.22?±?12.03 years; 53.1 % female) with clinical suspicion of bronchopulmonary carcinoid were evaluated with ⁶⁸Ga-DOTATOC PET/CT and ¹⁸F-FDG PET/CT. The two imaging modalities were compared, considering the tissue diagnosis as the reference standard.

Results

Based on the reference standard 26 cases were carcinoid tumours [21 typical carcinoids (TC) and 5 atypical carcinoids (AC)] and 6 cases were non-carcinoid tumours. The sensitivity, specificity and accuracy of ⁶⁸Ga-DOTATOC PET/CT in the diagnosis of pulmonary carcinoid tumour were 96.15, 100 and 96.87 % respectively, whereas those of ¹⁸F-FDG PET/CT were 78.26, 11.1 and 59.37 % respectively. The maximum standardised uptake value (SUV_max) of TC on ⁶⁸Ga-DOTATOC PET/CT scan ranged from 3.58 to 55, while that of AC ranged from 1.1 to 32.5. ¹⁸F-FDG PET/CT was true-positive in all cases of AC and false-negative in eight cases of TC (sensitivity for TC 61.9 % and for AC 100 %).

Conclusion

⁶⁸Ga-DOTATOC PET/CT is a useful imaging investigation for the evaluation of pulmonary carcinoids. ¹⁸F-FDG PET/CT scan suffers from low sensitivity and specificity in differentiating the pulmonary carcinoids from other tumours.     

Evaluation of gross tumor size using CT, 18F-FDG PET, integrated 18F-FDG PET/CT and pathological analysis in non-small cell lung cancer

Purpose

The correlation of gross tumor sizes between combined ¹⁸F-FDG PET/CT images and macroscopic surgical samples has not yet been studied in detail. In the present study, we compared CT, ¹⁸F-FDG PET and combined ¹⁸F-FDG PET/CT for the delineation of gross tumor volume (GTV) and validated the results through examination of the macroscopic surgical specimen.

Methods

Fifty-two operable non-small cell lung cancer (NSCLC) patients had integrated ¹⁸F-FDG PET/CT scans preoperatively and pathological examination post-operation. Four separate maximal tumor sizes at X (lateral direction), Y (ventro-dorsal direction) and Z (cranio-caudal direction) axis were measured on ¹⁸F-FDG PET, CT, combined ¹⁸F-FDG PET/CT and surgical specimen, respectively. Linear regression was calculated for each of the three imaging measurements versus pathological measurement.

Results

No significant differences were observed among the tumor sizes measured by three images and pathological method. Compared with pathological measurement, CT size at X, Y, Z axis was larger, whereas combined ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET size were smaller. Combined ¹⁸F-FDG PET/CT size was more similar to the pathological size than that of ¹⁸F-FDG PET or CT. Results of linear regressions showed that integrated ¹⁸F-FDG PET/CT was the most accurate modality in measuring the size of cancer.

Conclusions

¹⁸F-FDG PET/CT correlates more faithfully with pathological findings than ¹⁸F-FDG PET or CT. Integrated ¹⁸F-FDG PET/CT is an effective tool to define the target of GTV in radiotherapy.     

18F-FDG PET/CT结合高分辨率CT对孤立性肺结节的诊断价值

目的探讨^18F-脱氧葡萄糖（FDG）PET／CT结合高分辨率CT（HRCT）对孤立性肺结节（SPN）的鉴别诊断价值。方法25例经手术病理检查或治疗随访证实的SPN（共27个）患者，同期行^18F—FDGPET／CT显像和病灶部位HRCT检查。^18F—FDGPET／CT用目测法结合半定量法判断良恶性。HRCT则根据病灶形态学特征判断良恶性。所得^18F—FDGPET／CT结果和^18F—FDGPET／CT与HRCT相结合结果分别与病理检查结果对照比较。结果27个SPN中15个恶性，12个良性。PET／CT正确诊断14个恶性和9个良性SPN。3个良性SPNPET／CT显像为阳性，其中2个经PET／CT和HRCT联合诊断为良性。联合诊断灵敏度和单纯PET／CT相同（93．3％），但特异性、阳性预测值、阴性预测值、准确性分别高于PET／CT（91．7％、93．3％、91．7％和93．7％对75．0％、82．4％、90．0％和85．2％）。结论^18F—FDGPET／CT结合HRCT是有效的无创性鉴别SPN良恶性的方法。