18F-dihydroxyphenylalanine PET in patients with biochemical evidence of medullary thyroid cancer: relation to tumor differentiation.

Curative treatment for recurrent medullary thyroid cancer (MTC), diagnosed by rising serum calcitonin, is surgery, but tumor localization is difficult. Therefore, the value of 18F-dihydroxyphenylalanine PET (18F-DOPA PET), 18F-FDG PET, (99m)Tc-V-di-mercaptosulfuricacid (DMSA-V) scintigraphy, and MRI or CT was studied. METHODS: Twenty-one patients with biochemical recurrent or residual MTC underwent 18F-DOPA PET, 18F-FDG PET, DMSA-V scintigraphy, and MRI or CT. Patient- and lesion-based sensitivities were calculated using a composite reference consisting of all imaging modalities. RESULTS: In 76% of all patients with MTC, one or more imaging modalities was positive for MTC lesions. In 6 of 8 patients with a calcitonin level of <500 ng/L, imaging results were negative. In 15 patients with positive imaging results, 18F-DOPA PET detected 13 (sensitivity, 62%; with 4.6 lesions per patient [lpp]). Morphologic imaging (n = 19) was positive in 7 (sensitivity, 37%; 4.7 lpp), DMSA-V (n = 18) in 5 (sensitivity, 28%; 1.1 lpp), and 18F-FDG PET (n = 17) in 4 (sensitivity, 24%; 1.6 lpp). In a lesion-based analysis, 18F-DOPA PET detected 95 of 134 lesions (sensitivity, 71%), morphologic imaging detected 80 of 126 (sensitivity, 64%), DMSA-V detected 20 of 108 (sensitivity, 19%), and 18F-FDG PET detected 48 of 102 (sensitivity, 30%). In 2 of 3 patients with a calcitonin/carcinoembryonic antigen (CEA) doubling time of < or =12 mo, 18F-FDG PET performed better than 18FDOPA PET; in the third patient, 18F-FDG PET was not performed. CONCLUSION: MTC lesions are best detectable when serum calcitonin was >500 ng/L. 18F-DOPA PET is superior to 18F-FDG PET, DMSA-V, and morphologic imaging. With short calcitonin doubling times (< or =12 mo), 18F-FDG PET may be superior.     

Diagnostic utility of PET/CT with <Superscript>18</Superscript>F-DOPA and <Superscript>18</Superscript>F-FDG in persistent or recurrent medullary thyroid carcinoma: the importance of calcitonin and carcinoembryonic antigen cutoff

Purpose

This study sought to evaluate and compare the utility of 18-F-fluorodihydroxyphenylalanine (¹⁸F-DOPA) and 18-F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) for identification of lesions in patients with recurrent medullary thyroid carcinoma (MTC). In addition, we analyzed the correlation between the calcitonin (Ct), carcinoembryonic antigen (CEA) levels, each doubling time (DT), and PET positivity. We evaluated the reliability of the 150 pg/mL Ct cutoff set by the American Thyroid Association guidelines for further imaging (including ¹⁸F-DOPA PET/CT).

Methods

We prospectively recruited 18 patients with recurrent MTC, identified by elevation of Ct or CEA. Each patient underwent a ¹⁸F-FDG PET/CT and a ¹⁸F-DOPA PET/CT.

Results

Abnormal uptakes were detected with ¹⁸F-DOPA (n=12) and ¹⁸F-FDG (n=9), (sensitivity of 66.7% vs. 50%; p<0.01). Twenty-eight lesions were detected with ¹⁸F-DOPA vs. 16 lesions with ¹⁸F-FDG (1.56±1.5 vs. 0.89±1.18 lesions per patient; p=0.01). None of our patients showed additional lesions with ¹⁸F-FDG in comparison to ¹⁸F-DOPA. Patient-based detection rate increased significantly with Ct levels ≥150 pg/mL vs. Ct<150 pg/mL for both ¹⁸F-DOPA (sensitivity 90.9% vs. 28.6%; p=0.013) and ¹⁸F-FDG PET/CT (sensitivity 72.7% vs. 14.3%; p=0.025). Using a CEA cutoff of ≥5 ng/mL, detection rates of ¹⁸F-DOPA and ¹⁸F-FDG PET/CT were 81.1% and 72.7%, respectively. No correlation between Ct-DT or CEA-DT and PET positivity was found. Histological confirmation was obtained in eight patients.

Conclusions

¹⁸F-DOPA PET/CT appears to be superior to ¹⁸F-FDG PET/CT in detecting and locating lesions in patients with recurrent MTC. This technique tends to be especially useful in patients with negative results in other imaging modalities and Ct≥150 pg/mL or CEA≥5 ng/mL.

     

Comparison of 18F-DOPA, 18F-FDG and 68Ga-somatostatin analogue PET/CT in patients with recurrent medullary thyroid carcinoma

Purpose

To retrospectively evaluate and compare ¹⁸F-FDG, ¹⁸F-DOPA and ⁶⁸Ga-somatostatin analogues for PET/CT in patients with residual/recurrent medullary thyroid carcinoma (MTC) suspected on the basis of elevated serum calcitonin levels.

Methods

Included in the study were 18 patients with recurrent MTC in whom functional imaging with the three tracers was performed. The PET/CT results were compared on a per-patient basis and on a per-lesion-basis.

Results

At least one focus of abnormal uptake was observed on PET/CT in 13 patients with ¹⁸F-DOPA (72.2% sensitivity), in 6 patients with ⁶⁸Ga-somatostatin analogues (33.3%) and in 3 patients with ¹⁸F-FDG (16.7%) (p?18F-DOPA and ¹⁸F-FDG PET/CT (p?18F-DOPA and ⁶⁸Ga-somatostatin analogue PET/CT (p?=?0.04). Overall, 72 lesions were identified on PET/CT with the three tracers. ¹⁸F-DOPA PET/CT detected 85% of lesions (61 of 72), ⁶⁸Ga-somatostatin analogue PET/CT 20% (14 of 72) and ¹⁸F-FDG PET/CT 28% (20 of 72). There was a statistically significant difference in the number of lymph node, liver and bone lesions detected with the three tracers (p?18F-DOPA PET/CT and ¹⁸F-FDG PET/CT (p?18F-DOPA PET/CT and ⁶⁸Ga-somatostatin analogue PET/CT (p?Conclusion ¹⁸F-DOPA PET/CT seems to be the most useful imaging method for detecting recurrent MTC lesions in patients with elevated serum calcitonin levels, performing better than ¹⁸F-FDG and ⁶⁸Ga-somatostatin analogue PET/CT. ¹⁸F-FDG may complement ¹⁸F-DOPA in patients with an aggressive tumour.     

Predictive and prognostic value of 18F-DOPA PET/CT in patients affected by recurrent medullary carcinoma of the thyroid

Introduction

Medullary thyroid carcinoma (MTC) is a malignancy accounting for about 5–8% of thyroid cancers. Serum calcitonin and carcinoembryonic antigen (CEA) levels are widely used to monitor disease progression. However, prognostic factors able to predict outcomes are highly desirable. We, therefore, aimed to assess the prognostic role of ¹⁸F-DOPA PET/CT in patients with recurrent MTC.

Materials and methods

60 patients (mean age 64?±?13 years, range 44–82) with recurrent MTC were eligible from a multicenter database. All patients underwent a restaging ¹⁸F-DOPA PET/CT, performed at least 6 months after surgery. CEA/calcitonin levels, local recurrences, nodal involvement and metastases at PET/CT were recorded. SUVmax, SUVmean (also normalized to mediastinal uptake) and metabolic tumor volume were automatically calculated for each lesion, by placing a volume of interest around the lesion with 40% of peak activity as threshold for the automatic contouring. The patients were clinically and radiologically followed up for 21?±?11 months. Rate of progression-free survival (PFS), disease-specific survival (DSS) and incremental prognostic value of ¹⁸F-DOPA PET/CT over conventional imaging modalities were assessed by Kaplan–Meier curves and Log-Rank test. Cox regression univariate and multivariate analyses were performed for assessing predictors of prognosis.

Results

¹⁸F-DOPA PET/CT showed abnormal findings in 27 patients (45%) and resulted unremarkable in 33 (55%). PFS was significantly longer in patients with an unremarkable PET/CT scan (p?=?0.018). Similarly, an unremarkable PET/CT study was associated with a significantly longer DSS (p?=?0.04). ¹⁸F-DOPA PET/CT added prognostic value over other imaging modalities both for PFS and for DSS (p?<?0.001 and p?=?0.012, respectively). Neither semiquantitative PET parameters nor clinical or laboratory data were predictive of a worse PFS and DSS in patients with recurrent MTC.

Conclusion

¹⁸F-DOPA PET/CT scan has an important prognostic value in predicting disease progression and mortality rate.

     

Diagnostic impact of PET with <Superscript>18</Superscript>F-FDG, <Superscript>18</Superscript>F-DOPA and 3-<Emphasis Type="Italic">O</Emphasis>-methyl-6-[<Superscript>18</Superscript>F]fluoro-DOPA in recurrent or metastatic medullary thyroid carcinoma

Purpose In patients with medullary thyroid carcinoma (MTC), rising levels of the tumour markers calcitonin and CEA after primary surgery indicate tumour recurrence or metastases. The only chance of cure is the resection of localised tumour tissue. For positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) and ¹⁸F-dihydroxyphenylalanine (¹⁸F-DOPA), sensitivities of 78% and 63% have been reported, but in a considerable percentage of MTC patients the source of tumour marker elevation is not detected. The aim of this retrospective data evaluation was to compare the value of PET with ¹⁸F-FDG, ¹⁸F-DOPA and the amino acid tracer 3-O-methyl-6-[¹⁸F]fluoro-DOPA (¹⁸F-OMFD) in the detection of MTC recurrence. Methods Fifteen patients with elevated calcitonin were investigated with PET as part of their individual clinical work-up. All patients underwent ¹⁸F-FDG PET and ¹⁸F-DOPA PET, and ten patients underwent ¹⁸F-OMFD PET. Results With ¹⁸F-FDG, seven patients showed foci in the neck, mediastinum, upper abdomen or bone. In seven patients, ¹⁸F-DOPA revealed suspicious foci; five of these seven patients showed partially corresponding uptake of ¹⁸F-FDG in the neck and mediastinum. Two of these patients underwent surgery and metastases were verified. With ¹⁸F-OMFD, a small focus in the liver was suspected in one patient without a correlate on ¹⁸F-FDG PET, ¹⁸F-DOPA PET or conventional imaging. Conclusion ¹⁸F-FDG and ¹⁸F-DOPA showed foci that were highly suspicious for local recurrence or metastasis of MTC, although histological verification in these patients with numerous previous surgical interventions was performed in only two patients. The amino acid tracer ¹⁸F-OMFD had no diagnostic impact in these patients.     

<Superscript>18</Superscript>F-DOPA PET/CT in the diagnosis and localization of persistent medullary thyroid carcinoma

Purpose

To evaluate the performance of ¹⁸F-l-dihydroxyphenylalanine (¹⁸F-DOPA) PET/CT in the detection of locoregional and distant medullary thyroid carcinoma (MTC) metastases and to compare imaging findings with histological data.

Methods

We retrospectively evaluated 86 MTC patients with persistently high serum calcitonin levels after initial surgery who had undergone ¹⁸F-DOPA PET/CT between January 2007 and December 2014 in two referral centres. They were followed up for at least 6 months after the PET/CT assessment. The results were compared with histological data or with the findings obtained during follow-up using a complementary imaging modality.

Results

¹⁸F-DOPA PET/CT was positive in 65 of the 86 patients, corresponding to a patient-based sensitivity of 75.6 %. Distant metastatic disease (M1) was seen in 29 patients including 11 with previously unknown metastases revealed only by PET/CT. Among the 36 patients without distant metastatic spread, 25 had nodal involvement limited to the neck, and 10 of these 25 patients underwent reoperation. The lymph node compartment-based sensitivity of ¹⁸F-DOPA PET/CT was 100 % in the two institutions but lesion-based sensitivity was only 24 %. Preoperative and postoperative median calcitonin levels were 405 pg/mL (range 128 – 1,960 pg/mL) and 259 pg/mL (range 33 – 1,516 pg/mL), respectively. None of the patients achieved normalization of serum calcitonin after reoperation.

Conclusion

¹⁸F-DOPA PET/CT enables early diagnosis of a significant number of patients with distant metastasis. It has a limited sensitivity in the detection of residual disease but provides high performance for regional analysis. A surgical compartment-oriented approach could be the approach of choice whatever the number of nodes revealed by ¹⁸F-DOPA PET/CT.

     

18F-FDG PET/CT结合MRI在癫（癎）外科治疗中的应用

目的 探讨18F-脱氧葡萄糖（FDG）PET/CT结合MRI定位致（癎）灶,指导癫（癎）外科治疗的意义.方法 67例癫（癎）外科治疗患者术前均行18F-FDG PET/CT和MRI检查,根据术前评估以及术中皮质脑电图监测结果进行致（癎）灶切除术.术后长期随访,根据Engel分级将患者分为癫（癎）发作完全控制组（Engel Ⅰ）和癫（癎）发作未完全控制组（Engel Ⅱ～Ⅳ）,采用x2检验或Fisher精确检验对数据进行分析.结果 67例中48例患者术后癫（癎）发作完全控制（Engel Ⅰ,71.6%）,11例Engel Ⅱ,5例Engel Ⅲ,3例Engel Ⅳ.18F-FDG PET/CT定位定侧结果与MRI检查结果一致或基本一致者63例,其中71.4%（45/63）术后癫（癎）发作完全控制;18F-FDG PET/CT与MRI检查结果不一致者4例,其中3例术后癫（癎）发作完全控制,2组差异无统计学意义（Fisher精确检验,P＞0.05）.63例中MRI与18F-FDG PET/CT均发现局限性异常者为41例,其中80.5%（33/41）术后癫（癎）发作完全控制;MRI发现局限性病变,但18F-FDG PET/CT呈更广泛性代谢异常者20例,其中55.0%（11/20）术后癫（癎）发作完全控制,2组差异有统计学意义（x2=4.34,P＜0.05）.结论 18F-FDG PET/CT结合MRI可为致（癎）灶定位及预后评估提供重要信息.     

Diagnostic accuracy of 18F-FDG PET in restaging patients with medullary thyroid carcinoma and elevated calcitonin levels.

Medullary thyroid carcinoma (MTC) is a rare endocrine tumor arising from the C-cells of the thyroid gland. Calcitonin is the principal serum tumor marker. A rising calcitonin level after total thyroidectomy for localized disease generally indicates residual, recurrent, or metastatic disease. The role of (18)F-FDG PET in MTC remains somewhat unclear. We reviewed our own experience with (18)F-FDG PET in postthyroidectomy MTC patients with elevated calcitonin. METHODS: From our database, we identified patients with suspected residual, recurrent, or metastatic MTC and elevated calcitonin who had been referred for (18)F-FDG PET between January 2000 and October 2005. (18)F-FDG PET findings were classified as positive or negative on the basis of visual interpretation of the scan. Standardized uptake values (SUVs) were also calculated. The (18)F-FDG PET findings were verified by histopathologic examination, when available, or other imaging studies and clinical follow-up. Any negative (18)F-FDG PET result was considered false-negative. RESULTS: Twenty-eight patients underwent a total of 38 (18)F-FDG PET studies. Calcitonin levels ranged from 106 to 541,000 pg/mL (median, 7,260 pg/mL). There were 23 true-positive, 1 false-positive, and 14 false-negative (18)F-FDG PET scans, yielding an overall sensitivity of 62%. There was no true-positive finding when calcitonin levels were below 509 pg/mL (n = 5). Using an arbitrary cutoff of 1,000 pg/mL, we found that the sensitivity in scans with calcitonin levels greater than 1,000 pg/mL increased to 78% (21/27; 95% confidence interval, 58%-91%). The mean SUV of all lesions with (18)F-FDG uptake was 5.3 +/- 3.2 (range, 2.0-15.9). Among the 14 patients with false-negative (18)F-FDG PET findings, 8 had concurrent anatomic imaging studies and only 2 of these had positive findings. CONCLUSION: (18)F-FDG PET can detect residual, recurrent, or metastatic MTC with a reasonable sensitivity of 78% when the calcitonin level is above 1,000 pg/mL but appears of limited use if the calcitonin level is below 500 pg/mL.     

18F-FDG PET/CT与PET/MRI在结直肠癌肝转移诊断中的比较分析

目的:比较 18F-氟脱氧葡萄糖（FDG） PET/CT与PET/MRI显像对结直肠癌肝转移的诊断价值。 方法:回顾性分析2018年9月至2019年9月于宁波明州医院行全身 18F-FDG PET/CT显像及上腹部 18F-FDG PET/MRI显像,并疑似有结直肠癌肝转移...     

18F-FDG PET detection of lymph node metastases in medullary thyroid carcinoma.

Postsurgically elevated or increasing serum calcitonin levels strongly suggest the presence of residual or recurrent medullary thyroid carcinoma (MTC). Several imaging modalities (sonography, MRI, CT, scintigraphy with different types of radiolabeled ligands, etc.) are routinely used in an attempt to localize tumorous tissue, but such efforts often fail. In the search for a more reliable method, 18F-FDG PET was applied to detect tumor tissue of residual or recurrent MTC. METHODS: Forty patients with a postoperatively elevated plasma calcitonin level were included. These patients underwent routine diagnostic imaging procedures (CT, MRI, and 131I-metaiodobenzylguanidine [MIBG] whole-body planar scintigraphy or SPECT) and 18F-FDG PET examinations. Two independent experts visually analyzed the images provided by each method to detect pathologic lesions. Lymph nodes of > or = 1 cm in short diameter that were detected by radiologic methods were considered to be pathologic. 18F-FDG accumulation with a sharp contour reported by both independent observers was similarly regarded as pathologic. RESULTS: PET detected 270 foci with a high tracer accumulation, whereas only 116 lesions were detected by MRI and 141 by CT. The numbers of such foci determined by PET, MRI, and CT were 98, 34, and 34, respectively, in the neck; 25, 5, and 6, respectively, in the supraclavicular regions; and 117, 35, and 39, respectively, in the mediastinum. 131I-MIBG scintigraphy findings were positive for only 3 patients. CONCLUSION: For MTC patients with a postoperatively elevated plasma tumor marker level, PET was more sensitive and superior in localizing tumorous lymph node involvement than were the other imaging modalities, especially in the cervical, supraclavicular, and mediastinal lymphatic regions.     

The impact of 18F-FDG PET/CT on assessment of nasopharyngeal carcinoma at diagnosis

The aim of this study was to determine whether the use of whole-body (18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography (PET)/CT alters staging and management of nasopharyngeal carcinoma (NPC) when compared with current staging practice. 52 patients with Stage III-IV NPC without distant metastases on chest X-ray/CT, abdominal ultrasound or bone scan were recruited for the study. Whole-body (18)F-FDG PET/CT and MRI of the head and neck were performed. The scans were compared for extent of the primary tumour (PT), cervical nodal metastases (CNM) and distant metastases (DM). Any discordance in results was assessed with respect to staging and impact on management. MRI and (18)F-FDG PET/CT scans were discordant in 28 (54%) patients. There was discordance in the extent of PT at 28 sites; in all sites, MRI showed more extensive tumour involving the nasopharynx (n = 8), skull base (n = 14), brain (n = 4) and orbit (n = 2). There was also variation among the extent of CNM in four nodes of the retropharyngeal region, with the nodes being positive on MRI. (18)F-FDG PET /CT did not identify any additional distant metastases but did identify a second primary tumour in the colon. The additional use of (18)F-FDG PET/CT did not "up-stage" the overall stage or change management in any patient. In conclusion, there is discordance between MRI and (18)F-FDG PET/CT, and the additional use of (18)F-FDG PET/CT for the current assessment of NPC at diagnosis does not appear to be justified in this cohort of patients.     

Molecular imaging of brain tumors with 18F-DOPA PET and PET/CT

The objective of this study was to give an overview of the potential clinical utility of [18F]-L-dihydroxyphenylalanine (18F-DOPA) PET and PET/CT for imaging of brain tumors. Review articles and reference lists were used to supplement the search findings. 18F-DOPA has been investigated as a PET tracer for primary brain tumors, metastases of somatic cancer, and evaluation of relapse of pathology in patients with brain tumor after surgery and/or radiotherapy on the basis of enhanced cell proliferation. Available studies have provided encouraging preliminary results for diagnosis of brain tumors and relapse after surgery/radiotherapy. In the brain, excellent discrimination between tumor and normal tissue can be achieved because of the low physiological uptake of 18F-DOPA and the high ratio between tumor and normal hemispheric tissue. Information on evaluation of brain metastases is limited but encouraging. PET and PET/CT with 18F-DOPA are useful in diagnosing primary brain tumors and should be recommended in the diagnosis of relapse of disease after surgical treatment and/or radiotherapy. Semiquantitative analysis could improve diagnosis while correlative imaging with MRI is essential. Limits are due to low knowledge of potential pitfalls.     

Role of 18F-FDG PET/CT in the assessment of bone involvement in newly diagnosed multiple myeloma: preliminary results

Purpose Multiple myeloma (MM) is a malignant B cell and plasma cell disorder which involves the skeleton in more than 80% of patients at diagnosis. The aim of this study was to compare whole-body X-ray (WBXR), MRI and ¹⁸F-FDG PET/CT in patients with MM. Methods The study population comprised 28 newly diagnosed MM patients. Findings of ¹⁸F-FDG PET/CT were compared with those of WBXR and MRI with regard to the number and site of lesions detected. Results Comparing ¹⁸F-FDG PET/CT and WBXR, it was found that in 16/28 pts (57%) ¹⁸F-FDG PET/CT detected more lesions, all of which were located in the skeleton. Nine of these 16 patients had a completely negative WBXR survey. In 12/28 pts (43%) the two methods yielded equivalent findings. Comparing ¹⁸F-FDG PET/CT and MRI, it was found that in 7/28 pts (25%), ¹⁸F-FDG PET/CT detected more lytic bone lesions, all of which were located outside the field of view of MRI (bone lesions in six cases and a soft tissue lesion in one). In 14/28 pts (50%), ¹⁸F-FDG PET/CT and MRI detected the same number of lesions in the spine and pelvis, while in 7/28 pts (25%) MRI detected an infiltrative pattern in the spine whereas ¹⁸F-FDG PET/CT was negative. Conclusion ¹⁸F-FDG PET/CT appears to be more sensitive than WBXR for the detection of small lytic bone lesions, whereas it has the same sensitivity as MRI in detecting bone disease of the spine and pelvis. On the other hand, MRI may be superior to ¹⁸F-FDG PET/CT in diagnosing an infiltrative pattern in the spine. Therefore, careful evaluation of MM bone disease at diagnosis should include both MRI of the spine and ¹⁸F-FDG PET/CT.     

Clinical value of 18F-fluorodihydroxyphenylalanine positron emission tomography/computed tomography (18F-DOPA PET/CT) for detecting pheochromocytoma

Purpose

In detecting pheochromocytoma (PHEO), positron emission tomography (PET) with the radiolabelled amine precursor ¹⁸F-fluorodihydroxyphenylalanine (¹⁸F-DOPA) offers excellent specificity, while computed tomography (CT) provides high sensitivity and ability to localize lesions; therefore, the combination of these modalities could be advantageous in this setting. The aim of this study was to investigate whether combined ¹⁸F-DOPA PET/CT more accurately detects and localizes PHEO lesions than does each modality alone.

Methods

¹⁸F-DOPA PET, CT and ¹⁸F-DOPA PET/CT images of 25 consecutive patients undergoing diagnostic scanning of suspected sporadic or multiple endocrine neoplasia type 2 syndrome-associated PHEO were reviewed retrospectively in randomized sequence. Two blinded observers scored the images regarding the likelihood of PHEO being present and localizable. Results were correlated with subsequent clinical history and, when available, histology.

Results

Of the 19 lesions detected by all three modalities, PET identified each as positive for PHEO, but was unable to definitively localize 15 of 19 (79%). CT could definitively localize all 19 lesions, but could not definitively diagnose or exclude PHEO in 18 of 19 (95%) lesions. Furthermore, CT falsely identified as negative for PHEO one lesion which was judged to be positive for this tumor by both PET and PET/CT. Only in PET/CT scans were all 19 lesions accurately characterized and localized. On a per-patient basis, the sensitivity of ¹⁸F-DOPA PET/CT for PHEO was 100% and the specificity 88%, with a 100% positive predictive value and an 88% negative predictive value.

Conclusion

¹⁸F-DOPA PET/CT more accurately diagnoses and localizes adrenal and extra-adrenal masses suspicious for PHEO than do ¹⁸F-DOPA PET or CT alone.     

Ability of <Superscript>18</Superscript>F-DOPA PET/CT and fused <Superscript>18</Superscript>F-DOPA PET/MRI to assess striatal involvement in paediatric glioma

Purpose

To assess the diagnostic performance of ¹⁸F-DOPA PET/CT and fused ¹⁸F-DOPA PET/MRI in detecting striatal involvement in children with gliomas.

Methods

This retrospective study included 28 paediatric patients referred to our institution for the presence of primary, residual or recurrent glioma (12 boys, 16 girls; mean age 10.7 years) and investigated with ¹⁸F-DOPA PET/CT and brain MRI. Fused ¹⁸F-DOPA PET/MR images were obtained and compared with PET/CT and MRI images. Accuracy, sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) for striatal involvement were calculated for each diagnostic tool. Univariate and multivariate logistic analyses were applied to evaluate the associations between ¹⁸F-DOPA PET/CT and fused ¹⁸F-DOPA PET/MRI diagnostic results and tumour uptake outside the striatum, grade, dimension and site of striatal involvement (ventral and/or dorsal).

Results

Accuracy, sensitivity, specificity, PPV, and NPV were 100 % for MRI, 93 %, 89 %, 100 %, 100 % and 82 % for ¹⁸F-DOPA PET/MRI, and 75 %, 74 %, 78 %, 88 % and 58 % for ¹⁸F-DOPA PET/CT, respectively. ¹⁸F-DOPA PET/MRI showed a trend towards higher accuracy compared with ¹⁸F-DOPA PET/CT (p?=?0.06). MRI showed significantly higher accuracy compared with ¹⁸F-DOPA PET/CT (p?=?0.01), but there was no significant difference between MRI and ¹⁸F-DOPA PET/MRI. Both univariate and multivariate logistic analyses showed a significant association (OR 8.0 and 7.7, respectively) between the tumour-to-normal striatal uptake (T/S) ratio and the diagnostic ability of ¹⁸F-DOPA PET/CT (p?=?0.03). A strong significant association was also found between involvement of the dorsal striatum and the ¹⁸F-DOPA PET/CT results (p?=?0.001), with a perfect prediction of involvement of the dorsal striatum by ¹⁸F-DOPA PET/MRI.

Conclusion

Physiological striatal ¹⁸F-DOPA uptake does not appear to be a main limitation in the evaluation of basal ganglia involvement.¹⁸F-DOPA PET/CT correctly detected involvement of the dorsal striatum in lesions with a T/S ratio >1, but appeared to be less suitable for evaluation of the ventral striatum. The use of fused ¹⁸F-DOPA PET/MRI further improves the accuracy and is essential for evaluation of the ventral striatum.

     

The effects of carbidopa on uptake of 6-18F-Fluoro-L-DOPA in PET of pheochromocytoma and extraadrenal abdominal paraganglioma.

6-(18)F-fluoro-l-3,4-dihydroxyphenylalanine ((18)F-DOPA) PET is a useful tool for the detection of certain neuroendocrine tumors, especially with the preadministration of carbidopa, an inhibitor of DOPA decarboxylase. Whether carbidopa also improves (18)F-DOPA PET of adrenal pheochromocytomas and extraadrenal paragangliomas is unknown. The aim of this study was to investigate the sensitivity of (18)F-DOPA PET in the detection of paraganglioma and its metastatic lesions and to evaluate whether tracer uptake by the tumors is enhanced by carbidopa. METHODS: Two patients with nonmetastatic adrenal pheochromocytoma, and 9 patients with extraadrenal abdominal paraganglioma (1 nonmetastatic, 8 metastatic), underwent whole-body CT, MRI, baseline (18)F-DOPA PET, and (18)F-DOPA PET with oral preadministration of 200 mg of carbidopa. The dynamics of tracer uptake by these lesions and the physiologic distribution of (18)F-DOPA in normal tissues were recorded. RESULTS: Seventy-eight lesions were detected by CT or MRI, 54 by baseline (18)F-DOPA PET (P = 0.0022 vs. CT/MRI), and 57 by (18)F-DOPA PET plus carbidopa (P = 0.0075 vs. CT/MRI, not statistically significant vs. baseline). In reference to findings on CT and MRI, the sensitivities of baseline (18)F-DOPA PET were 47.4% for lesions and 55.6% for positive body regions, versus 50.0% (lesions) and 66.7% (regions) for (18)F-DOPA PET plus carbidopa (neither is statistically significant vs. baseline). Compared with baseline, carbidopa detected additional lesions in 3 (27%) of 11 patients. Carbidopa increased the mean (+/-SD) peak standardized uptake value in index tumor lesions from 6.4 +/- 3.9 to 9.1 +/- 5.6 (P = 0.037). Pancreatic physiologic (18)F-DOPA uptake, which may mask adrenal pheochromocytoma, is blocked by carbidopa. CONCLUSION: Carbidopa enhances the sensitivity of (18)F-DOPA PET for adrenal pheochromocytomas and extraadrenal abdominal paragangliomas by increasing the tumor-to-background ratio of tracer uptake. The sensitivity of (18)F-DOPA PET for metastases of paraganglioma appears to be limited.     

Evaluation of 18F-FDG uptake and arterial wall calcifications using 18F-FDG PET/CT.

Glucose metabolic activity expressed as (18)F-FDG uptake may be increased in active atherosclerotic plaque. Calcium depositions are often increased in mature atherosclerotic plaque. The purpose of the present study was to assess the patterns of vascular-wall (18)F-FDG uptake and CT calcifications using combined PET/CT. METHODS: One hundred twenty-two consecutive patients over the age of 50 (47 women and 75 men; mean age, 66 +/- 9 y) undergoing whole-body (18)F-FDG PET/CT for tumor assessment were retrospectively evaluated. PET, CT, and PET/CT slices were generated for review. Abnormal vascular findings in major arteries in the chest and abdomen were categorized as PET positive (PET+), PET negative (PET-), CT positive (CT+), or CT negative (CT-). The topographic relationship between increased vascular-wall (18)F-FDG uptake on PET and the presence of calcifications on CT was assessed on PET/CT fused images, with abnormal sites further classified as PET+/CT+, PET+/CT-, or PET-/CT+. The presence of CT calcifications and increased vascular-wall (18)F-FDG uptake was correlated with age, sex, presence of cardiovascular risk factors, and cardiovascular disease. RESULTS: Abnormal findings were identified at 349 sites. CT calcifications (CT+) were observed at 320 sites (92%) of 100 patients (82%), more commonly in men (P < 0.03), in older patients (P < 0.0001), in patients with hypertension (P < 0.003) or hyperlipidemia (P < 0.04), and in smokers (P < 0.008). Increased vascular-wall (18)F-FDG uptake (PET+) was observed at 52 sites (15%) of 38 patients (31%), more commonly in men (P < 0.02), in older patients (P < 0.0001), and in patients with hypertension (P < 0.02), and was borderline in patients with cardiovascular disease (P = 0.057). PET+ and CT+ findings correlated in 12 patients, a PET+/CT- pattern was found in 18 patients, and 8 patients had increased vascular-wall (18)F-FDG uptake in sites with and without calcifications (PET+/CT+, CT-). Twenty-two patients (18%) had a PET-/CT- pattern. CONCLUSION: Hybrid PET/CT can be used to identify and to correctly localize vascular-wall (18)F-FDG activity. Increased vascular-wall (18)F-FDG activity was found in 15% of sites and CT calcifications were noted in 92% of sites, with congruent findings in 7%. The clinical significance of the relationship between vascular-wall (18)F-FDG uptake and CT calcifications needs to be assessed by further prospective studies with long-term follow up.     

18F-FDG PET and CT/MRI in oral cavity squamous cell carcinoma: a prospective study of 124 patients with histologic correlation.

Accurate evaluation of primary tumors and cervical lymph node status of squamous cell carcinoma (SCC) of the oral cavity is important to treatment planning and prognosis prediction. In this prospective study, we evaluated the use of 18F-FDG PET, CT/MRI, and their visual correlation for the identification of primary tumors and cervical nodal metastases of SCC of the oral cavity with histologic correlation. METHODS: One hundred twenty-four patients with pathologically proven diagnoses of oral cavity SCC underwent 18F-FDG PET and CT/MRI within 2 wk before surgery. We interpreted 18F-FDG PET, CT/MRI, and visually correlated 18F-FDG PET and CT/MRI separately to assess the primary tumors and their regional lymph node status. We recorded lymph node metastases according to the neck level system of imaging-based nodal classification. Histopathologic analysis was used as the gold standard for assessment of the primary tumors and lymph node involvement. We analyzed differences in sensitivity and specificity among the imaging modalities using the McNemar test. The receiver-operating-characteristic (ROC) curve and calculation of the area under the curve were used to evaluate their discriminative power. RESULTS: The accuracy of 18F-FDG PET, CT/MRI, and their visual correlation for the identification of primary tumors was 98.4%, 87.1%, and 99.2%, respectively. The sensitivity of 18F-FDG PET for the identification of nodal metastases on a level-by-level basis was 22.1% higher than that of CT/MRI (74.7% vs. 52.6%, P < 0.001), whereas the specificity of 18F-FDG PET was 1.5% lower than that of CT/MRI (93.0% vs. 94.5%, P = 0.345). The sensitivity and specificity of the visual correlation of 18F-FDG PET and CT/MRI were 3.2% and 1.5% higher than those of 18F-FDG PET alone (77.9% vs. 74.7%, P = 0.25; 94.5% vs. 93.0%, P = 0.18, respectively). The area under the curve obtained from the ROC curve showed that 18F-FDG PET was significantly superior to CT/MRI for total nodal detection (0.896 vs. 0.801, P = 0.002), whereas the visual correlation of 18F-FDG PET and CT/MRI was modestly superior to 18F-FDG PET alone (0.913 vs. 0.896, P = 0.28). CONCLUSION: 18F-FDG PET is superior to CT/MRI in the detection of cervical status of oral cavity SCC. The sensitivity of 18F-FDG PET for the detection of cervical nodal metastasis on a level-by-level basis was significantly higher than that of CT/MRI, whereas their specificities appeared to be similar. Visual correlation of 18F-FDG PET and CT/MRI showed a trend of increased diagnostic accuracy over 18F-FDG PET alone but without a statistically significant difference, and its sensitivity was still not high enough to replace pathologic lymph node staging based on neck dissection.     

18F-FDG PET/CT在黑色素瘤中的应用价值

目的 探讨18F-脱氧葡萄糖(FDG)PET/CT显像在黑色素瘤诊断、临床分期及监测治疗后肿瘤复发与转移灶中的应用价值.方法 黑色素瘤患者61例,均进行18F-FDG PET/CT全身显像.所有PET、CT及PET/CT融合图像均通过融合软件进行帧对帧对比分析.肿瘤病灶根据病理学检查、多种影像学检查及临床随访结果诊断.结果 18F-FDG PET/CT显像对黑色素瘤病灶检出的灵敏度、特异性和准确性分别为90.9%(40/44)、88.2%(15/17)和90.2%(55/61).其中12例治疗前患者中,18F-FDG PET/CT显像诊断的灵敏度为83.3%(10/12).在黑色素瘤病灶局部切除、尚未进行其他治疗的9例患者中,5例残余病灶18F-FDG PET/CT显像检出3例;4例远处转移灶患者全被检出,提高了临床分期,改变了治疗方案.首先发现转移性黑色素瘤病灶并且手术切除后,寻找原发灶的7例患者中,18F-FDG PET/CT检出原发灶2例,4例其他转移灶全被检出.黑色素瘤患者根治术后监测肿瘤复发或转移患者33例,18F-FDG PET/CT显像灵敏度、特异性和准确性分别为100.0%(19/19)、85.7%(12/14)和93.9%(31/33).与同期临床其他影像学检查比较,18F-FDG PET/CT显像发现更多,33例患者中,16例(48.5%)病灶提高临床分期;7例(21.2%)排除可疑病灶,降低临床分期;10例(30.3%)检出病灶与临床一致.结论 18F-FDG PET/CT显像对于黑色素瘤的诊断,残余病灶、复发病灶及转移灶的检出,临床分期的明确具有重要价值.     

Breast cancer staging in a single session: whole-body PET/CT mammography

Our objective was to compare the diagnostic accuracy of an all-in-one protocol of whole-body 18F-FDG PET/CT and integrated 18F-FDG PET/CT mammography with the diagnostic accuracy of a multimodality algorithm for initial breast cancer staging. METHODS: Forty women (mean age, 58.3 y; range, 30.8-78.4 y; SD, 12 y) with suspected breast cancer were included. For the primary tumor, we compared 18F-FDG PET/CT mammography versus MRI mammography; for axillary lymph node status, 18F-FDG PET/CT versus clinical investigation and ultrasound; and for distant metastases, 18F-FDG PET/CT versus a multimodality staging algorithm. Histopathology and clinical follow-up served as the standard of reference. The Fisher exact test evaluated the significance of differences (P < 0.05). Alterations in patient management caused by 18F-FDG PET/CT were documented. RESULTS: No significant differences were found in the detection rate of breast cancer lesions (18F-FDG PET/CT, 95%; MRI, 100%; P = 1). 18F-FDG PET/CT correctly classified lesion focality significantly more often than did MRI (18F-FDG PET/CT, 79%; MRI, 73%; P < 0.001). MRI correctly defined the T stage significantly more often than did 18F-FDG PET/CT (MRI, 77%; 18F-FDG PET/CT, 54%; P = 0.001). 18F-FDG PET/CT detected axillary lymph node metastases in 80% of cases; clinical investigation/ultrasound, in 70%. This difference was not statistically significant (P = 0.067). Distant metastases were detected with 18F-FDG PET/CT in 100% of cases, and the multimodality algorithm identified distant metastases in 70%. This difference was not statistically significant (P = 1). Three patients had extraaxillary lymph node metastases that were detected only by PET/CT (cervical, retroperitoneal, mediastinal/internal mammary group). 18F-FDG PET/CT changed patient management in 12.5% of cases. CONCLUSION: Our data suggest that a whole-body 18F-FDG PET/CT mammography protocol may be used for staging breast cancer in a single session. This initial assessment of the 18F-FDG PET/CT protocol indicates similar accuracy to MRI for the detection of breast cancer lesions. Although MRI seems to be more accurate when assessing the T stage of the tumor, 18F-FDG PET/CT seems able to more accurately define lesion focality. Although 18F-FDG PET/CT mammography was able to detect axillary lymph node metastases with a high sensitivity, this method cannot soon be expected to replace the combination of clinical examination, ultrasound, and sentinel lymph node biopsy for axillary assessment.