Initial experience with FDG-PET/CT in the evaluation of breast cancer

Purpose We retrospectively reviewed FDG-PET/CT images in patients with breast cancer to determine whether PET/CT improved the level of diagnostic confidence as compared with PET and to compare PET/CT and CT findings at the location of suspected malignancies.Methods The study included 75 patients with known breast cancer. The initial PET/CT study for each patient was retrospectively reviewed to determine whether improved diagnostic confidence (IDC) regarding lesion localization and characterization was observed with PET/CT as compared with PET alone. PET/CT and CT findings were compared regarding lesion characterization and staging in 69 of the 75 patients, and in the case of discordant findings, comparison with histological or informative follow-up results was also performed.Results Fifty of the 75 patients exhibited increased FDG uptake in a total of 95 regions. In the comparison of PET/CT and PET, PET/CT resulted in IDC in 30 (60%) of these 50 patients and in 52 (55%) of the 95 regions. In the comparison between PET/CT and CT in 69 patients, PET/CT demonstrated a significantly better accuracy than CT (P<0.05). PET/CT showed definitely positive findings in 60 regions with malignancies, among which CT exhibited positive findings in 43 (72%). PET/CT and CT accurately staged 59 (86%) and 53 (77%) of the 69 patients, respectively.Conclusions PET/CT added incremental diagnostic confidence to PET in more than 50% of patients and regions with increased FDG uptake. PET/CT accurately detected more regions with malignancies than did CT. This initial evaluation suggests that PET/CT is preferable to PET or CT in the diagnosis of breast cancer.     

FDG-PET/CT in re-staging of patients with lymphoma

The aim of this study was to evaluate the clinical significance of combined fluorine-18 fluorodeoxyglucose positron emission tomography and computed tomography (FDG-PET/CT) in patients with lymphoma, and to compare the FDG-PET/CT staging results with those of FDG-PET and CT alone. Twenty-seven patients were studied. Each patient had clinical follow-up for >12 months and entered complete follow-up evaluation. Patient-based evaluation showed a sensitivity of 78% for CT alone, 86% for FDG-PET alone, 93% for CT and FDG-PET read side by side, and 93% for combined FDG-PET/CT imaging. Region-based evaluation showed a sensitivity for regional lymph node involvement of 61%, 78%, 91% and 96% respectively. FDG-PET/CT imaging is superior to CT alone (P=0.02) and has additional benefit over FDG-PET alone due to exact anatomical localisation. We conclude that FDG-PET/CT imaging is accurate in re-staging lymphoma and offers advantages over separate FDG-PET and CT imaging.     

Dual-modality FDG-PET/CT in follow-up of patients with recurrent iodine-negative differentiated thyroid cancer

The usefulness of combined 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography and computed tomography (FDG-PET/CT) in locating suspected recurrence in patients with iodine-negative differentiated thyroid cancer (DTC) was evaluated. Thirty-six patients with DTC and suspected iodine-negative recurrence underwent restaging with FDG-PET/CT. The images of CT, FDG-PET, both modalities viewed side by side (CT+PET), and FDG-PET/CT were evaluated by two physicians separately. Imaging results were correlated with either histology (n = 20) and/or clinical follow-up of at least 36 months. Recurrent disease was diagnosed in 22/36 patients. FDG-PET alone, CT alone, CT+PET, and FDG-PET/CT showed a sensitivity of 82%, 73%, 91%, and 96%, respectively. Specificities were 79%, 71%, 79%, and 100%, respectively. FDG-PET/CT significantly improved specificity compared with CT+PET and resulted in a further treatment modification in 5/36 patients (14%). CT alone was especially sensitive for lung metastases, FDG-PET alone for the remainder of the body. Accurate fusion of functional and morphologic data by FDG-PET/CT improves the staging accuracy of patients with suspected recurrence of iodine-negative DTC. This has an impact on patient management in a substantial number of patients.     

Performance of integrated FDG-PET/contrast-enhanced CT in the diagnosis of recurrent uterine cancer: comparison with PET and enhanced CT

Purpose  To evaluate the accuracy of integrated positron emission tomography and computed tomography (PET/CT) with iodinated contrast agent and ¹⁸F-fluorodeoxyglucose (FDG) in the diagnosis of suspected uterine cancer recurrence and to assess the impact of PET/CT findings on clinical management, compared with PET alone and enhanced CT alone. Methods  Of 103 women who had undergone treatment for histopathologically proven uterine cervical or endometrial cancer, 90 underwent FDG-PET/contrast-enhanced CT examination for suspected recurrence. PET-alone, CT-alone, and fused PET/CT images were interpreted by two radiologists by consensus for each investigation. Lesion status was determined on the basis of histopathology, radiological imaging and clinical follow-up for longer than 6 months. Differences among the three modalities were tested using the Cochran Q test, followed by multiple comparisons using the McNemar test with Bonferroni adjustment. Results  Patient-based analysis showed that the sensitivity, specificity, and accuracy of PET alone were 79.5% (35/44), 73.9% (34/46), and 76.7% (69/90), respectively, whereas those of CT alone were 68.2% (30/44), 87.0% (40/46), and 77.8% (70/90), respectively, and those of PET/CT were 90.9% (40/44), 93.5% (43/46), and 92.2% (83/90), respectively. PET/CT findings resulted in a change of management in 38 of the 90 patients (42%) with an additional effect on patient management in 13 patients (14%) diagnosed by CT alone and 14 patients (16%) diagnosed by PET alone. Conclusion  FDG-PET/contrast-enhanced CT is a more accurate modality for assessing recurrence of uterine cancer, and led to more appropriate subsequent clinical management than that resulting from PET alone or enhanced CT alone.     

Anatomo-metabolic characteristics of atelectasis in F-18 FDG-PET/CT imaging

PURPOSE: To evaluate the structural and metabolic characteristics of atelectasis in FDG-PET/CT. METHODS: Twenty one consecutive patients (13 males, 8 females, median age 67 years) with CT features of atelectasis, undergoing PET/CT imaging for preoperative staging of histologically proven malignancies (20 lung cancer and 1 ovarian cancer metastasis to lung), were included in the study. RESULTS: Hounsfield units of atelectasis (-383.58+/-189, range -631 to 82) were significantly higher than in normal lung (-756+/-67.46, range -839 to -555; P=0.0001), and lower than in malignant tissue (35+/-19, range 4-77; P=0.0001). The main patterns of FDG uptake observed in atelectasis were diffuse and homogenous. The standard uptake value (SUV) in atelectasis was low to moderate (SUV(avg): 1.13+/-0.50; SUV(max): 1.44+/-0.54), and generally lower than in tumor tissue (SUV(avg): 6.25+/-3.58, range 2.0-16.5), but always higher than in normal lung (0.56+/-0.18 and 0.70+/-0.23, respectively) (P=0.0001). There was a positive correlation between the density of atelectatic lesions and the degree of uptake, with no relationship to size. CONCLUSION: There is a positive relationship between the density of collapsed lung and the intensity of FDG uptake. FDG uptake in atelectasis is higher than in normal lung, and generally lower than in tumor tissue.     

The value of FDG-PET/CT in assessing single pulmonary nodules in patients at high risk of lung cancer

Purpose  To evaluate whether PET/low-dose CT (ldCT) using ¹⁸F-fluorodeoxyglucose (FDG) improves characterization of indeterminate single pulmonary nodules (SPNs) in patients at high risk of lung cancer. Methods  Retrospective analysis of 307 patients who underwent FDG-PET/CT for indeterminate SPNs identified 93 (70 men, age range 46–90 years) at high risk of lung cancer (age >40 years, minimum 10 pack-year smokers). SPNs were evaluated for the presence and intensity of FDG avidity and ldCT patterns. The performance of visual and semiquantitative FDG-PET/ldCT algorithms for characterization of SPNs was compared to that of ldCT. Incongruent FDG-PET and ldCT patterns were analyzed for significance in further patient management. Results  Malignancy was diagnosed in 38% patients. FDG avidity defined 33 SPNs as true-positive (TP) and 2 as false-negative (FN) (malignant), and 41 as true-negative (TN) and 17 as false-positive (FP) (benign). For SUVmax of 2.2 (by ROC analysis) there were 27 TP, 8 FN, 48 TN and 10 FP SPNs. LdCT defined 34 TP, 1 FN, 28 TN and 30 FP lesions. Of the FP lesions on ldCT, 60% were FDG-negative. Visual PET/ldCT analysis had a sensitivity of 94%, a specificity of 70%, an accuracy of 80%, a positive predictive value (PPV) of 66%, and a negative predictive value (NPV) of 95% as compared to 77%, 83%, 81%, 73%, 86% for semiquantitative PET/ldCT and 97%, 48%, 66%, 53%, 96% for ldCT, respectively. Both PET/ldCT algorithms had statistically significantly higher specificity and accuracy than ldCT. Semiquantitative analysis showed significantly higher PPV and lower sensitivity and NPV than found with ldCT. Conclusion  A single screening procedure encompassing FDG-PET and ldCT may improve screening for lung cancer in high-risk patients. The significantly improved specificity may potentially reduce FP ldCT results and further unnecessary invasive procedures.     

Accuracy of integrated FDG-PET/contrast-enhanced CT in detecting pelvic and paraaortic lymph node metastasis in patients with uterine cancer

The purpose is to evaluate the accuracy of integrated ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography ((CT) with intravenous contrast medium in detecting pelvic and paraaortic lymph node metastasis in patients with uterine cancer, with surgical and histopathological findings used as the reference standard. Forty-five patients with endometrial or uterine cervical cancer underwent radical hysterectomy, including pelvic lymphadenectomy with or without paraaortic lymphadenectomy, after PET/CT. PET/CT findings were interpreted by two experienced radiologists in consensus. The criterion for malignancy on PET/CT images was increased tracer uptake by the lymph node, independent of node size. The overall node-based sensitivity, specificity, PPV, NPV and accuracy of PET/CT for detecting nodal metastases were 51.1% (23/45), 99.8% (1,927/1,931), 85.2% (23/27), 98.9% (1,927/1,949) and 98.7% (1,950/1,976), respectively. The sensitivity for detecting metastatic lesions 4 mm or less in short-axis diameter was 12.5% (2/16), that for between 5 and 9 mm was 66.7% (16/24), and that for 10 mm or larger was 100.0% (5/5). The overall patient-based sensitivity, specificity, positive predictive value ((PPV), negative predictive value (NPV), and accuracy were 50% (6/12), 90.9% (30/33), 66.7% (6/9), 83.3% (30/36) and 80.0% (36/45), respectively. Integrated FDG-PET/contrast-enhanced CT is superior to conventional imaging, but only moderately sensitive in predicting lymph node metastasis preoperatively in patients with uterine cancer.     

Diagnosis of Cardiac Metastasis from Endometrial Cancer by F-18 FDG-PET/CT

We report a case of a 59-year-old woman with right ventricular metastasis of undifferentiated endometrial cancer. Cardiac metastasis from endometrial cancer is a very rare finding. The case demonstrates that undifferentiated endometrial cancer is capable of metastasizing, presumably through a hematogenous route, to unexpected distant organs. These unexpected sites should not be undermined in the restaging and surveillance of these patients.     

Usefulness of FDG-PET/CT in the detection of pancreatic metastases from lung cancer

Objective  The objective of this study was to assess the ability to detect pancreatic metastasis of lung cancer and to clarify the degree of fluorodeoxyglucose (FDG) accumulation and computed tomography (CT) characteristics of pancreatic metastasis from lung cancer. Methods  A total of 573 patients (415 men and 158 women) with lung cancer were retrospectively evaluated. All patients underwent FDG-positron emission tomography (PET)/CT with contrast-enhanced CT for first=stage (313 patients; initial study group) or follow-up study (260 patients; follow-up study group). A lesion was regarded as positive for metastasis on the basis of visual judgment of the degree of increased metabolism by two experienced and independent interpreters, supported by semiquantitative evaluation on the basis of calculation of the maximum standardized uptake value (SUV_max). Results  Abnormal accumulations in the pancreas were detected in 5 of 313 patients (1.60%) in the initial study group, and 6 of 260 patients (2.31%) in the follow-up study group. Seven of these patients had adenocarcinoma, three had small cell carcinoma, and the rest had large cell endocrine carcinoma. Tumor sizes (longitudinal diameter), measured by CT, of these 11 patients ranged from 6 mm to 52 mm (mean ± SD 8.3 mm ± 11.9 mm), and SUV_max for 1 h ranged from 3.37 to 11.1 (mean ± SD 6.12 ± 2.43). Three of these pancreatic lesions were difficult to determine by routine transaxial images, and detection was obvious only by thin-slice images or multiplanar reconstruction images. Contrast-enhanced CT showed gradual fill-in from the peripheral portion to the center. In addition, 10 of 11 cases did not show main pancreatic duct dilatation even if the tumor size was large. Conclusions  Metastases to the pancreas in lung cancer patients are not so rare and radiologists first have an important role to detect the pancreatic mass and then suggest to metastasis as the likely diagnosis. For this purpose, FDG-PET/CT has an advantage in depicting unsuspected pancreatic metastasis from lung cancer, particularly that which is not detected by CT alone.     

Performance profile of FDG-PET and PET/CT for cancer screening on the basis of a Japanese Nationwide Survey

Objective The aim of this study is to survey the situation of ¹⁸F-fluorodeoxyglucose-positron emission tomography (FDG-PET) cancer screening in Japan and to describe its performance profile. Methods “FDG-PET for cancer screening” was defined as FDG-PET or positron emission tomography and computed tomography (PET/CT) scan with or without other tests performed for cancer screening of healthy subjects. We sent questionnaires regarding FDG-PET cancer screening to 99 facilities in which FDG-PET tests were performed during the fiscal year 2005. Replies were obtained from 68 of the 99 facilities, of which 46 facilities performed FDG-PET cancer screening. The total number of subjects who underwent FDG-PET cancer screening was 50 558. From 38 of 46 facilities, reliable results of thorough examinations were obtained for the subjects who were positive by FDG-PET and/or one or more of the combined screening tests was performed and were referred for further evaluation. The total number of subjects in these 38 facilities amounted to 43 996. Results A total of 50 558 healthy subjects underwent FDG-PET (including PET/CT) scanning with or without other tests for cancer screening in 46 PET centers during the fiscal year of 2005 in Japan. Thorough examination was indicated for 9.8% of the cases as a result of positive findings suggesting possible cancer. On analyzing 43 996 cases from 38 PET centers from which detailed information was obtained, 500 cases of cancers (1.14%) were found, of which 0.90% were PET positive and 0.24% were PET negative, resulting in the relative sensitivity of PET being 79.0%. Cancers of the thyroid, colon/rectum, lung, and breast were most frequently found (107, 102, 79, and 35 cases, respectively) with high PET sensitivity (88%, 90%, 80%, and 92%). PET showed an overall positive predictive value of 29.0%. PET/CT had a better detection rate, sensitivity, and positive predictive value than dedicated PET (P < 0.01). Conclusions We were able to clarify the performance profile of “FDG-PET for cancer screening” on the basis of a Japanese nationwide survey. The number of facilities possessing PET is increasing steadily, highlighting the necessity of evaluating the usefulness of “FDG-PET cancer screening” as soon as possible by undertaking long-term investigations of large series of subjects.     

Integrated FDG-PET/CT vs. standard radiological examinations: Comparison of capability for assessment of postoperative recurrence in non-small cell lung cancer patients

Purpose

The purpose of this study was to prospectively and directly compare diagnostic capabilities of whole-body integrated FDG-PET/CT and standard radiologic examination for assessment of recurrence in postoperative non-small cell lung cancer (NSCLC) patients.

Materials and methods

A total of 92 consecutive pathologically diagnosed NSCLC patients (65 males, 27 females; mean age, 71 years) underwent pathologically and surgically proven complete resection, followed by prospective whole-body FDG-PET/CT and standard radiological examinations. Final diagnosis of recurrence was based on the results of more than 1 year of follow-up and/or pathological examinations. On both methods, the probability of recurrence was assessed in each patient by using a five-point visual scoring system, and the each final diagnosis was made by consensus between two readers. Kappa analyses were performed to determine inter-observer agreement for both methods, and ROC analyses were used to compare capability of the two methods for assessment of postoperative recurrence on a per-patient basis. Sensitivity, specificity and accuracy were also compared between PET/CT and standard radiological examination by means of McNemar's test.

Results

All inter-observer agreements were almost perfect (integrated PET/CT: κ = 0.89; standard radiological examination: κ = 0.81). There were no statistically significant differences in area under the curve, sensitivity, specificity and accuracy between integrated FDG-PET/CT and standard radiologic examinations (p > 0.05).

Conclusion

Integrated FDG-PET/CT can be used for assessment of postoperative recurrence in NSCLC patients with accuracy as good as that of standard radiological examinations.     

Chronic thyroiditis in patients with advanced breast carcinoma: metabolic and morphologic changes on PET-CT

Purpose  To investigate clinical implications of FDG uptake in the thyroid glands in patients with advanced breast carcinoma by comparing metabolic and morphologic patterns on positron emission tomography (PET)/computed tomography (CT). Methods  The institutional review board waived the requirement for informed consent. A retrospective analysis was performed in 146 women (mean age 54 years) with advanced breast carcinoma who received systemic treatment. All patients underwent PET-CT before and after treatment. All PET-CT studies were reviewed in consensus by two reviewers. Morphologic changes including volume and mean parenchymal density of the thyroid glands were evaluated. Maximum standardized uptake value (SUVmax) and total lesion glycolysis (TLG) were determined to evaluate metabolic changes. These parameters were compared between patients with chronic thyroiditis who received thyroid hormone replacement therapy and those who did not. Results  Of the 146 patients, 29 (20%) showed bilaterally diffuse uptake in the thyroid glands on the baseline PET-CT scan. The SUVmax showed a linear relationship with volume (r = 0.428, p = 0.021) and the mean parenchymal density (r = −0.385, p = 0.039) of the thyroid glands. In 21 of the 29 patients (72%) with hypothyroidism who received thyroid hormone replacement therapy, the volume, mean parenchymal density, SUVmax, and TLG of the thyroid glands showed no significant changes. In contrast, 8 of the 29 patients (28%) who did not receive thyroid hormone replacement therapy showed marked decreases in SUVmax and TLG. Conclusion  Diffuse thyroid uptake on PET-CT represents active inflammation caused by chronic thyroiditis in patients with advanced breast carcinoma. Diffuse thyroid uptake may also address the concern about subclinical hypothyroidism which develops into overt disease during follow-up.     

Integrated FDG-PET/CT compared with intravenous contrast-enhanced CT for evaluation of metastatic regional lymph nodes in patients with resectable early stage esophageal cancer

Objective  To assess whether integrated fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) can improve the diagnostic accuracy of metastatic regional lymph nodes (LNs) in esophageal cancer compared with contrast enhanced CT (CECT). Methods  We examined 180 consecutive patients with esophageal cancer by integrated PET/CT between April 2006 and March 2007. Eighteen patients (M:F 14:4) underwent radical esophagectomy after evaluations by PET/CT and CECT of 5–7-mm-thick slices 70–80 s after injection. Regional LNs of esophageal cancer were retrospectively reviewed on CECT images by two blinded evaluators on the basis of the following cutoff sizes: 7 mm for all regional LNs (Protocol A), 10 mm for paratracheal LNs (Protocol B), and 7 mm for others. In addition, the maximum standardized uptake value (SUVmax) on PET/CT was evaluated for positive uptake by LNs. Results  Of 210 LNs excised at surgery, 25 were positive and 185 were negative for metastasis at pathology. The PET/CT images identified 15 true-positive and 184 truenegative LNs, whereas CECT identified 15 true positives and 176 true negatives in Protocol A, and 14 true positives and 180 true negative in Protocol B. The sensitivity, specificity, accuracy, positive, and negative predictive values of PET/CT were respectively 60.0%, 99.5%, 94.8%, 93.8%, and 94.8%, whereas those of CECT were 60.0%, 95.1%, 91.0%, 62.5%, and 94.6% (Protocol A) and 56.0%, 97.3%, 92.4%, 73.7%, and 94.2% (Protocol B). A comparison of the two CECT protocols revealed fewer false-positive LNs in Protocol B, but slightly lower sensitivity in Protocol B than in Protocol A. Substantial numbers of false-positive LNs were determined by CECT in the paratracheal regions (6 of 9, 66.7%) and CECT revealed central necrosis in 4 of 15 (26.7%) true-positive LNs > 1.8 cm. The mean SUVmax on PET/CT was 2.9 (range 1.7–5.5) in true-positive LNs. The smallest LN metastasis detectable by PET/CT was 6 mm. Conclusions  Integrated PET/CT improves the PPV of regional LNs when compared with CECT.     

The diagnostic usefulness of FDG-PET/CT in detecting tumor recurrence not evident in whole body I scan in differentiated thyroid carcinoma

Objective

Patients with differentiated thyroid carcinoma (DTC) have generally an encouraging prognosis, however, some patients develop an increasing level of serum thyroglobulin (Tg) without detection of a recurrent tumor using conventional imaging tools such as the iodine-131 whole-body scanning (I¹³¹ scan). The objective of our study was to evaluate the clinical significance of [F¹⁸]-FDG-PET/CT in detection of tumor recurrence or metastases, in comparison to conventional imaging such as the I¹³¹ scan.

Patients and methods

Between January 2013 and June 2013, [18F]-FDG-PET/CT examination was done for 12 DTC patients with elevated thyroglobulin levels and who did not show any pathological lesions when conventional imaging modalities were used. All involved patients had undergone total thyroidectomy, and who had been followed-up by whole body iodine scan [F¹⁸]-FDG PET/CT data were evaluated for detecting recurrent DTC lesions in study patients and compared with those of other radiological and/or cytological investigations.

Results

Five of 12 patients (41.6 %) showed pathological [F18]-FDG uptake in the absence of abnormal uptake in whole body iodine scan.

Conclusion

[F18]-FDG-PET/CT affords a valuable diagnostic method in detection of recurrence or metastasis in patients with DTC who are tumor-free on conventional imaging studies with high Tg levels.     

Role of FDG-PET and PET/CT in the diagnosis and management of vasculitis

Purpose

to investigate the role of FDG-PET and PET/CT in the evaluation of vasculitis.

Materials and methods

a systematic revision of the papers published in PubMed/Medline until December 2009 was done.

Results

FDG-PET and PET/CT have been proven to be valuable in the diagnosis of large-vessel vasculitis, especially giant cells arteritis with sensitivity values ranging 77% to 92%, and specificity values ranging 89% to 100%. In particular, FDG-PET/CT has demonstrated the potential to non-invasively diagnose the onset of the vasculitis earlier than traditional anatomical imaging techniques, thus enabling prompt treatment. False positive results mainly occur in the differential diagnosis between vasculitis and atherosclerotic vessels in elderly patients. Another area where FDG-PET/CT is gaining wider acceptance is in monitoring response to therapy; it can reliably detect the earliest changes of disease improvement post-therapy, and persistent activity is an indicator of non-responders to therapy. A few data have been reported about medium/small vessel vasculitis.

Discussion

FDG-PET and PET/CT have proven utility: (a) in the initial diagnosis of patients suspected of having vasculitis particularly in those who present with non-specific symptoms; (b) in the identification of areas of increased FDG uptake in which a biopsy should be done for obtaining a diagnosis; (c) in evaluating the extent of the disease; (d) in assessing response to treatment.     

Combined metabolic and morphologic imaging in thyroid carcinoma patients with elevated serum thyroglobulin and negative cervical ultrasonography: role of <Superscript>124</Superscript>I-PET/CT and FDG-PET

Purpose This study sought to compare iodine-124 positron emission tomography/computed tomography (¹²⁴I-PET/CT) and 2-[¹⁸F]fluoro-2-deoxy-d-glucose- (FDG-) PET in the detection of recurrent differentiated thyroid carcinoma (DTC) lesions in patients with increasing serum thyroglobulin (Tg), Tg-antibodies, or both, but without pathological cervical ultrasonography. We assessed the lesion detection accuracy of ¹²⁴I-PET alone, CT alone, ¹²⁴I-PET/CT, FDG-PET, and all these modalities combined. Material and methods The study included 21 patients (9 follicular, 12 papillary DTC) who had been rendered disease-free by thyroidectomy and radioiodine treatment (RIT) and followed up for 21–275 months after the last RIT. In all patients, FDG-PET was performed first. Within 1 week, ¹²⁴I-PET/CT was performed 24 h after oral administration of 43 ± 11 MBq ¹²⁴I. Imaging results were correlated with further clinical follow-up with (n = 12) or without (n = 9) post-study histology as the reference standard. Results The sensitivities for DTC lesion detection were: ¹²⁴I-PET, 49%; CT, 67%; ¹²⁴I-PET/CT, 80%; FDG-PET, 70%; and all modalities combined, 91%. For local recurrences (distant metastases), the sensitivities were: ¹²⁴I-PET, 60% (45%); CT, 20% (84%); and FDG-PET, 65% (71%). One-third of lesions demonstrated pathological tracer uptake with both ¹²⁴I- and FDG-PET, while two-thirds were positive with only one of these modalities. Conclusion Used together, ¹²⁴I-PET and CT allow localization of foci of highly specific ¹²⁴I uptake as well as non-iodine-avid lesions. The combination of ¹²⁴I-PET/CT and FDG-PET improves restaging in recurrent DTC by enabling detection on whole-body scans of local recurrence or metastases that are often not found if only one of the methods or other imaging modalities are applied.     

Post-therapy surveillance of patients with uterine cancers: value of integrated FDG PET/CT in the detection of recurrence

PURPOSE: The purpose of this study was to prospectively determine the diagnostic accuracy of PET/CT in the detection of recurrence in patients with treated uterine cancers. METHODS: Twenty-five women, ranging in age from 37 to 79 years (mean 58.9 years), who underwent primary surgical treatment for either a cervical or an endometrial cancer met the inclusion criterion of the study, which was suspicion of recurrence based on results of routine follow-up procedures. PET/CT was performed after administration of 18F-fluorodeoxyglucose (FDG); two readers interpreted the images in consensus. Histopathological findings or correlation with results of subsequent clinical and imaging follow-up examinations served as the reference standard. Diagnostic accuracy of PET/CT was reported in terms of the proportion of correctly classified patients and lesion sites. RESULTS: Tumour recurrence was found at histopathological analysis or follow-up examinations after PET/CT in 14 (56%) of the 25 patients. Patient-based sensitivity, specificity, positive predictive value, negative predictive value and accuracy of PET/CT for detection of tumour recurrence were 92.9%, 100.0%, 100.0%, 91.7% and 96.0%, respectively. Lesion site-based sensitivity, specificity, positive predictive value, negative predictive value and accuracy of PET/CT were 94.7%, 99.5%, 94.7%, 99.5% and 99.0%, respectively. CONCLUSION: This preliminary study shows that PET/CT may be an accurate method for the evaluation of recurrence in patients who have been treated for uterine cancers and are undergoing follow-up.     

FDG-PET/CT finding of high uptake in pulmonary alveolar microlithiasis

Pulmonary alveolar microlithiasis (PAM) is a rare lung disease characterized by progressive intra-alveolar calcification. We present a case of PAM with abnormal accumulation of ¹⁸F-fluorodeoxyglucose (FDG) in both lungs. A 55-year-old man was referred to our hospital for progressive dyspnea. He had been diagnosed with PAM 25 years earlier by transbronchial lung biopsy. High-resolution computed tomography revealed multiple dense calcifications with little aerated lung. Combined positron emission tomography and computed tomography using ¹⁸F-FDG (FDG-PET/CT) showed the abnormal accumulation of FDG in both lungs with a maximal standardized uptake value of 7.3. High FDG uptake was observed mainly in the lung regions showing sparing calcification. The patient died of respiratory failure a month later and an autopsy revealed no significant inflammatory changes in either lung. We suspect that the markedly enhanced pulmonary FDG uptake may have some relation to the pathophysiology of PAM.     

Prognostic value of SUVmax measured by Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography with Computed Tomography in Patients with Pancreatic Cancer

Purpose

Recent studies have been conducted on the relationship between fluorodeoxyglucose (FDG) uptake in F-18 FDG PET/CT and prognosis in patients with pancreatic cancer, but these studies have been carried out in small numbers of patients. The aim of this retrospective study was to determine in a large number of patients whether glucose metabolism as assessed by F-18 FDG PET/CT provides prognostic information independent of established prognostic factors in patients with pancreatic cancer.

Methods

We reviewed retrospectively the medical records of 165 patients (men 105, women 60, mean age 67 ± 10 years) with a diagnosis of pancreatic cancer that had undergone F-18 FDG PET/CT as part of a pretreatment workup from January 2004 to December 2009. Subsequently, all patients underwent surgery, cyberknife, radiotherapy, and/or chemotherapy. For the analysis, patients were classified by age, demographic data, maximum standardized uptake value (SUVmax), size, location, serum level of CA19-9, type of treatment, and AJCC stage. The relationship between FDG uptake and survival was analyzed using the Kaplan-Meier with log-Rank test and Cox’s proportional-hazard regression methods.

Results

Median survival for all 165 study subjects was 290 days and median SUV by PET/CT was 5.8 (range: 0–25.1). Patients were allocated to high (> 4.1) and low (≤4.1) SUV groups, and median survivals of these patients were 229 days and 610 days, respectively, which were significantly different (p < 0.0001). Furthermore, SUVmax was found to be significantly related to survival in each stage, i.e., there were 1267 days in stage I, 440 days in stage II, 299 days in stage III, and 143 days in stage IV (p < 0.0001). The median survival was also found to be significantly related to tumor size (p = 0.001), site (p = 0.0298), serum level of CA19-9 (p = 0.0017), distant metastasis (p < 0.0001), and type of treatment (p < 0.0001). Multivariate analysis study revealed that the patients with a low SUV (p = 0.0298), a lower serum level of CA19-9 (p = 0.0071), a lower stage (p = 0.0017), and no distant metastasis (p < 0.0001) had longer survivals. In addition, SUVmax values were found to have a similar hazard ratio of distant metastasis; it was well known predictor. Furthermore, SUVmax values showed a higher hazard ratio than that of other clinicopathologic predictors.

Conclusion

The present study shows that SUVmax on F-18 FDG PET/CT can provide a prognostic information in patients with pancreatic cancer.     

Role of FDG PET/CT for detection of primary tumor in patients with extracervical metastases from carcinoma of unknown primary

AimTo explore the diagnostic performance of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) to detect the primary tumor site in patients with extracervical metastases from carcinoma of unknown primary (CUP). We evaluated patient outcomes as overall survival (OS).Materials and methodsIn a single-center, retrospective study (2005–2019), patients with extracervical metastases from CUP underwent FDG PET/CT to detect primary tumor sites. The final diagnosis was based on histopathology/or clinical follow-up of at least 12 months.ResultsA total of 83 patients [Male 41 (49%), mean age 59 ± 14 years, range: 32–83 years] fulfilled the inclusion/exclusion criteria and were enrolled for analysis. The primary tumor was detected in 36 out of 83 (43%) patients based on histopathology/or clinical follow-up. PET/CT suggested the primary tumor site in 39 (47%) patients with diagnostic accuracy of 87%, sensitivity 89%, specificity 85%, PPV 82%, NPV 91% and detection rate 39%. Patients with oligometastases (<3) (2.16 years, 1.04–2.54) and primary unidentified (1 year, 0.34–2.14) had longer median survival time compared to the patients with multiple metastases (0.67 years, 0.17–1.58, p = 0.009) and primary identified (0.67 years,0.16–1.33, p = 0.002). The SUVmax of the primary or metastatic lesions with maximum uptake was not significantly related to survival.ConclusionsPET/CT could reveal the primary tumor site in 39% of the patients. It demonstrated the metastatic disease burden and distribution in patients with ‘primary obscured’, which directs management. Patients with multiple metastases and primary identified had a poorer prognosis. In patients with primary unidentified after PET/CT, a further search was futile.