Adjunctive role of dual time point imaging in evaluating bone lesions with increased 18F-PSMA-1007 uptake

Background@#Non-specific focal uptake in the skeleton is a diagnostic pitfall on 18F-PSMA-1007 PET/CT, but adjunctive measures to aid interpretation of these lesions are currently lacking. We present two cases where dual time point imaging provided additional information. @*Case Presentation@#The first patient had a PI-RADS 3 lesion on MRI. No PSMA-avid abnormality was seen on PET, save for focal uptake in the right pubis with no anatomic correlate. Additional imaging showed a decrease in lesion SUV, and this was interpreted as benign. Another patient, diagnosed with prostate cancer, had multiple PSMA-avid pelvic foci. Two suspiciously malignant bone lesions had increasing SUV trend after dual time point imaging despite only faint sclerosis on CT. In contrast, one faint PSMA-avid lesion with no anatomic abnormality was read as benign after a decrease in SUV. A decrease in lesion SUV may point to a benign etiology, while an increase would heighten suspicion for malignancy. One possible molecular explanation is that a true PSMA-overexpressing lesion would bind to the tracer for a longer period than a false positive.@*Conclusion@#Dual time point imaging provides additional information that may be useful in the interpretation of non-specificskeletal lesions with increased 18F-PSMA-1007 uptake.

The clinical value of 18F-FDG PET/CT dual-time-point imaging in diagnosing aortic graft infection / 中华胸心血管外科杂志

Objective:To explore the diagnostic value of 18F-deoxyglucose (FDG) PET/CT dual-time-point imaging (DTPI) in the diagnosis of aortic grafts infection (AGI). Methods:Forty-two patients with suspected AGI were prospectively recruited in this DTPI study from October 2014 to October 2021. There were 35(83%) males and 7 females, mean age (54±15) years old, range 22-79 years old. PET/CT image quality was scored as 5 grading scale. Semi-quantitative analysis of DTPI data was performed using maximum standardized uptake value (SUVmax) of suspected AGI lesions. The percentage of SUVmax change between initial and delayed images were recorded as retention index (RI). Management of Aortic Graft Infection Collaboration (MAGIC) criteria were used as the diagnostic reference criteria for AGI.Results:According to the MAGIC criteria, 27 patients (64%) were positive for AGI, and 15 patients (36%) were negative. The mean RI of AGI was higher than that of non-AGI ones[(26.7±18.9)% vs. (6.4 ±18.8)%, P<0.01]. The sensitivity, specificity, and accuracy of initial SUVmax ≥6 with the presence of AGI was 88.9%, 73.3%, and 83.3%, respectively. Delayed SUVmax ≥6 improved the sensitivity (96.3%) and accuracy (88.1%) for diagnosing AGI. DTPI with 15% increment as the optimal cut-off value of RI improved the specificity (93.3%) and accuracy (90.5%) for diagnosing AGI. Fifteen (56%, 15/27) AGI patients had improved image quality grading on the delayed images, leading to more accurately delineating the detailed extent of the infected aortic graft. Conclusion:18F-FDG PET/CT DTPI has better diagnostic performance for AGI than conventional Single-time-point PET/CT imaging by improving image quality as well as enhancing delineation of infected aortic graft extent.

Dual Time Point 18F-FDG PET/CT Imaging Identifies Bilateral Renal Tuberculosis in an Immunocompromised Patient with an Unknown Primary Malignancy / 감염과화학요법

18F-FDG PET/CT imaging is an established imaging modality for cancer staging and response assessment. Its role in identifying infective and inflammatory pathologies from malignancy is debated. Dual time - point imaging is a refined technique used to overcome this interpretational dilemma. We present a 59 year old male with an unknown primary malignancy who was referred for a 18F-FDG PET/CT imaging. Images revealed primary lung malignancy with co existing bilateral renal tuberculosis which otherwise would have gone amiss or would have been considered as metastases.

Value of regular and dual-time-point FDG PET/CT imaging in detecting recurrence and metastasis after a curative esophagectomy in esophageal carcinoma / 中华放射肿瘤学杂志

Objective To evaluate the clinical value of regular and dual-time-point 18-fluorodeoxyglucose positron emission tomography-CT(FDG PET/CT)imaging for recurrence and metastasis in esophageal carcinoma(EC)after curative esophagectomy. Methods A retrospective study was done on 48 patients received curative esophagectomy, who underwent FDG PET/CT scans to detect doubtful recurrent or metastatic lesions. The diagnostic accuracy of FDG PET-CT was assessed with the help of pathological findings as well as clinical or follow-up data. Using Fisher's Exact Test from SPSS 11.5 to analyze the data.Results Of the 48 patients, after a median follow-up of 21.5 months, 61 sites of local and regional recurrence or metastasis were finally confirmed in 34 patients. The sensitivity, specificity and accuracy of regular FDG PET/CT imaging in detecting recurrence of all sites were 93.44%, 74.29% and 86.46%respectively. The specificity and accuracy of local recurrence and regional metastasis were 57.14% ,78.95% and 77.78% ,84.62%, respectively. The sensitivity, specificity and accuracy of dual-time-point FDG PET/ CT imaging in detecting local and regional recurrence(96.97% ,96.00% and 96.55%)were higher than those of regular FDG PET/CT(90.90%, 72.00% and 82.76%)and there were significant differences of specificity and accuracy(P = 0.049, P = 0.029). Conclusions Regular FDG PET/CT imaging is highly effective in detecting recurrence and metastasis in EC patients after curative esophagectomy despite the low specificity and accuracy. Dual-time-point FDG PET/CT imaging can elevate the specificity and accuracy.

Dual time point imaging of FDG PET/CT in a tuberculous spondylodiscitis

Dual Time Point Imaging (DTPI) technique is a specialised protocol adopted in 18F-Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) imaging. This technique is claimed to be useful in differentiating malignant and infective lesions. The authors adopted this technique in a patient diagnosed with tuberculous spondylodiscitis and psoas abscess which demonstrated higher Maximum Standardized Uptake Value (SUVmax) during initial scans as compared with those obtained on delayed scans. The SUVmax changes between the two time points are believed to be a valuable finding for chronic granulomatous infective lesions such as tuberculosis.

(18)F-FDG PET/CT for the Preoperative Diagnosis of Papillary Thyroid Microcarcinoma: The Value of Dual Time Point Imaging / 핵의학분자영상

PURPOSE: We studied the patterns of FDG uptake of primary papillary thyroid microcarcinoma (PTMCa) lesions and benign thyroid nodules in dual time point (18)F-FDG PET/CT imaging. MATERIALS AND METHODS: Consecutive 134 patients (154 lesions) with PTMCa and 49 patients (61 nodules) with benign thyroid nodules equal to or less than 1.0 cm who underwent dual time point (18)F-FDG PET/CT study before surgery were enrolled. We calculated the maximum standardized uptake value of PTMCa and benign nodules in both time points, and percent change of SUVmax (delta%SUVmax) and lesion to background ratio of SUVmax (delta%L:B ratio) between both time points. The mean time interval between scans was 23.4+/-4.4 minutes (thyroid to thyroid interval: 10.7+/-4.4 minutes). RESULTS: The mean of SUVmax of PTMCa was increased from 4.9+/-4.3 to 5.3+/-4.7 (p<0.001) and delta%SUVmax was 12.3+/-23.6%. But, the mean of SUVmax of benign nodules was no definite change (2.1+/-1.0 to 2.1+/-1.3, p=0.686) and delta%SUVmax was -0.3+/-20.5%. Of the 154 PTMCa, 100 nodules (64.9%) showed an increase in SUVmax over time, while 19 (31.1%) of the 61 benign thyroid nodules showed an increase (p<0.001). The dual time point (18)F-FDG PET/CT found more PTMCa in visual assessment (62.3% vs. 76.6%, p=0.006), even in smaller than 0.5 cm (38.6% vs. 60.0%, p=0.011). CONCLUSION: Dual time time (18)F-FDG PET/CT imaging was more useful than single time point (18)F-FDG PET/CT imaging for distinction between PTMCa and benign nodule, especially when nodule showed equivocal or negative findings in single time point (18)F-FDG PET/CT imaging or was smaller than 0.5 cm.

Value of dual-time-point 18FDG PET-CT imaging on involved-field radiotherapy for hilar and mediastinal metastatic lymph nodes in non-small cell lung cancer / 中华放射肿瘤学杂志

Objective To discuss the value of dual-time-point 18FDG PET-CT imaging on involved field radiotherapy for hilar and mediastinal metastatic lymph nodes in patients with non-small cell lung cancer (NSCLC).Methods Fifty-four patients with NSCLC were included in this analysis,including 34 men and 20 women with mean age of 59(34-76)years.Two sequential PET-CT scans given 3-5 days before surgery were standard single-time-point imaging for the whole body and delayed imaging for the thorax.The pathologic data were used as golden standard to determine the difference between the standard single-time-point and dual-time-point FET-CT imaging in the definition of gross target volume(GTV)of involved-field radiotherapy for metastatic lymph nodes. Results For hilar metastatic lymph nodes,the GTV defined by single-time-point imaging was consistent with pathologic GTV in 21 patients(39%),comparing with 31 patients(57%) by dual-time-point imaging.Using pathologic data as golden standard,GTV alteration defined by single-time-point imaging had statisticaly significant difference comparing with that defined by dual-time-point imaging(u=519.00,P=0.023).For mediastinal metastatic lymph nodes,the GTV defined by single-time-point imaging was consistent with pathologic GTV in 30 patients(56%),comparing with 36 patients(67%)by dual-time-point imaging.Using pathologic data as golden standard.GTV alteration defined by single-time-point imaging had no statisticaly significant difference comparing with that defined by dual-time-point imaging(u=397.50,P=0.616).Conclusions For patients with NSCLC receiving involved-field radiotherapy,GTV definition for hilar and mediastinal metastatic lymph nodes by dual-time-point imaging is more consistent with that by pathologic data.Dual-time-point imaging has a larger value in terms of target delineation for hilar and mediastinal metastatic lymph nodes.