Digital versus analogue PET in [68Ga]Ga-PSMA-11 PET/CT for recurrent prostate cancer: a matched-pair comparison

European Journal of Nuclear Medicine and Molecular Imaging - Digital PET/CT scanners represent a significant step forward in molecular imaging. We report here the clinical impact of digital PET in...     

<Superscript>68</Superscript>Ga-PSMA-11 dynamic PET/CT imaging in biochemical relapse of prostate cancer

Objectives

We aim to investigate the pharmacokinetics and distribution of the recently clinically introduced radioligand ⁶⁸Ga-PSMA-11 in men with recurrent prostate cancer (PC) by means of dynamic and whole-body PET/CT. The correlation between PSA levels and ⁶⁸Ga-PSMA-11 PET parameters is also investigated.

Methods

31 patients with biochemical failure after primary PC treatment with curative intent (median age 71.0 years) were enrolled in the analysis. The median PSA value was 2.0 ng/mL (range?=?0.1 – 130.0 ng/mL) and the median Gleason score was 7 (range?=?5 – 9). 8/31 (25.8 %) of the included patients had a PSA value?<?0.5 ng/ml. All patients underwent dynamic PET/CT (dPET/CT) scanning (60 min) of the pelvis and lower abdomen as well as whole-body PET/CT with ⁶⁸Ga-PSMA-11. dPET/CT assessment was based on qualitative evaluation, SUV calculation, and quantitative analysis based on a two-tissue compartment model and a non-compartmental approach leading to the extraction of fractal dimension (FD).

Results

22/31 patients (71.0 %) were ⁶⁸Ga-PSMA-11-positive, while 9/31 (29.0 %) patients were ⁶⁸Ga-PSMA-11-negative. The median PSA value in the ⁶⁸Ga-PSMA-11-positive group was significantly higher (median?=?2.35 ng/mL; range?=?0.19 – 130.0 ng/mL) than in the ⁶⁸Ga-PSMA-11-negative group (median value: 0.34 ng/mL; range?=?0.10 – 4.20 ng/mL). A total of 76 lesions were semi-quantitatively evaluated. PC recurrence-associated lesions demonstrated a mean SUV_average?=?12.4 (median?=?9.0; range?=?2.2 – 84.5) and mean SUV_max = 18.8 (median?=?14.1; range?=?3.1 – 120.3). Dynamic PET/CT studies of the pelvis revealed the following mean values for the PC recurrence-suspicious lesions: K₁?=?0.26, k₃?=?0.30, influx?=?0.14 and FD?=?1.24. Time–activity curves derived from PC-recurrence indicative lesions revealed an increasing ⁶⁸Ga-PSMA-11 accumulation during dynamic PET acquisition. Correlation analysis revealed a moderate, but significant, correlation between PSA levels and the number of lesions detected on ⁶⁸Ga-PSMA-11 PET/CT (r?=?0.54) and between PSA levels and SUV_average (r?=?0.48) or SUV_max (r?=?0.44).

Conclusions

Ga-PSMA-11 PET/CT demonstrated an overall detection rate of 71.0 % 60 min p.i. of the radiotracer in a mixed patient population with respect to PSA levels and including patients with very low PSA values. Higher PSA values were associated with a higher detection rate. The tracer uptake in PC-recurrence-indicative lesions is increasing during the 60 minutes of dynamic PET acquisition.

     

68Ga-PSMA-11 dose reduction for dedicated pelvic imaging with simultaneous PET/MR using TOF BSREM reconstructions

European Radiology - When increasing the PET acquisition time to match the longer MRI protocol in simultaneous PET/MR, the injected PET tracer dose can possibly be lowered to reduce radiation...     

68Ga-PSMA-11 PET/CT in patients with recurrent prostate cancer—a modified protocol compared with the common protocol

European Journal of Nuclear Medicine and Molecular Imaging - 68Ga-PSMA-11 PET/CT is commonly performed at 1 h post injection (p.i.). However, various publications have demonstrated that most...     

68Ga-PSMA-11 PET imaging in patients with ongoing androgen deprivation therapy for advanced prostate cancer

Annals of Nuclear Medicine - Prostate-specific membrane antigen (PSMA) targeted positron emission tomography (PET) imaging significantly improved the detection of recurrent prostate cancer (PCa)....     

Impact of 68 Ga-PSMA-11 PET staging on clinical decision-making in patients with intermediate or high-risk prostate cancer

Accurate staging is of major importance to determine the optimal treatment modality for patients with prostate cancer. Positron emission tomography (PET) with prostate-specific membrane antigen (PSMA) is a promising technique that outperformed conventional imaging in the detection of nodal and distant metastases in previous studies. However, it is still unclear whether the superior sensitivity and specificity also translate into improved patient management. The aim of this study was to assess the performance of 68Ga-PSMA-11 PET for staging of intermediate and high-risk prostate cancer and its potential impact on disease management. In this retrospective analysis, 116 patients who underwent 68Ga-PSMA-11 PET/CT or MRI scans for staging of their intermediate or high-risk prostate cancer between April 2016 and May 2018 were included. The potential impact of 68Ga-PSMA-11 PET staging on patient management was assessed within a simulated multidisciplinary tumour board where hypothetical treatment decisions based on clinical information and conventional imaging alone was determined. This treatment decision was compared with the treatment recommendation based on clinical information and 68Ga-PSMA-11 PET imaging. The primary tumour was positive on 68Ga-PSMA-11 PET in 113 patients (97%). Nodal metastases were detected in 28 patients (24%) and bone metastases in 14 patients (12%). Compared with clinical staging and conventional imaging, 68Ga-PSMA-11 PET resulted in new information in 42 of 116 patients (36%). In 32 of 116 patients (27%), this information would most likely have changed the management into a different therapy modality (15 patients, 13%) or adjusted treatment details (e.g. modification of radiotherapy field or lymph node dissection template; 17 patients, 14%). Information from 68Ga-PSMA-11 PET staging has the potential to change the management in more than a fourth of the patients who underwent PET staging for their intermediate to high-risk prostate cancer. Whether these more personalized 68Ga-PSMA-11 PET-based treatment decisions will improve patient outcome needs further investigation.     

Reproducibility of standardized uptake values of same-day randomized <Superscript>68</Superscript>Ga-PSMA-11 PET/CT and PET/MR scans in recurrent prostate cancer patients

Objective

Positron emission tomography in association with magnetic resonance imaging (PET/MR) and ⁶⁸Ga-PSMA-11 has shown superior detection in recurrent prostate cancer patients as compared to PET/computed tomography (PET/CT). There are, however, several technological differences between PET/CT and PET/MR systems which affect the PET image quality. The objective of this study was to assess the reproducibility of PET/CT and PET/MR SUV’s in recurrent prostate cancer patients. We randomized the patients regarding the order of the PET/CT and PET/MR scans to reduce the influence of tracer uptake as a function of time.

Methods

Thirty patients, all with biochemical recurrence after radical prostatectomy, underwent whole-body PET/CT and PET/MR scans after intravenous injection of a single dose of ⁶⁸Ga-PSMA-11. Fifteen patients underwent PET/CT first and 15 patients underwent PET/MR first. Volumes of interest on tumor lesions were outlined and maximum standardized uptake value (SUVmax) corrected for lean body mass was calculated. Correlation and agreement between scans were assessed by generalized linear mixed-effects models and Bland–Altman analysis. The association between SUV, patient characteristics and imaging parameters was assessed.

Results

Eighteen of the 30 evaluated patients had at least one positive lesion, giving an overall detection rate of 60%. In total, there were 34 visible lesions: 5 local recurrences, 22 lymph node metastases and 7 bone metastases. One group acquired PET/CT and PET/MR at median time points of 63.0 and 159.0 min, while the other group acquired PET/MR and PET/CT at median time points of 92.0 and 149.0 min. SUVmax between scans was linearly correlated, described by the equation Y(PET/CT SUVmax)?=?0.75?+?1.00?×?(PET/MR SUVmax), on average 20% higher on PET/CT than on PET/MR. SUV associated significantly only with type of lesion, scan time post-injection and acquisition time per bed position.

Conclusions

SUVmax from PET/CT and PET/MR are linearly correlated, on average 20% higher on PET/CT than on PET/MR and should, therefore, not be used interchangeably in patient follow-up.

     

11C-胆碱显像在18F—FDG显像诊断不明确肝占位病变患者中的应用

目的研究11C-胆碱PET／CT显像在18F-脱氧葡萄糖（FDG）PET／CT显像诊断不明确的肝占位病变中的应用价值。方法对18F—FDGPET／CT诊断不明确的20例患者共25个肝占位病变,行肝局部11C-胆碱PET／CT显像。病灶处出现11C-胆碱局限性摄取增高者考虑为阳性。将最大标准摄取值（SUVmax）和靶／肝放射性（T／L）比值作为半定量分析指标。采用SPSS11．5软件,行Mann-Whitney和Kruskal—Wallis秩和检验及,检验。结果25个肝占位性病变中,21个为肝细胞癌,3个为血管瘤,1个为霉菌性肉芽肿。11c-胆碱显像对肝细胞癌灶的阳性检测率为66．7％（14／21）。11c-胆碱显像对高分化肝细胞癌的阳性检测率高于对中、低分化肝细胞癌（8／9和2／5）。肝癌阳性组、阴性组和良性病变组的T／L比值差异有统计学意义（1．70±0．35,0．86±0．15和0．36±0．18,X^2=19．00,P〈0．01）。肝癌阳性组和阴性组间的病灶大小和甲胎蛋白（AFP）水平差异无统计学意义（Mann—Whitney U=39．00,P〉0．05和U=16．00,P〉0．05）。结论11C-胆碱PET／CT能在较大程度上弥补18F—FDGPET／CT对肝细胞癌检测的不足,其更适合检测高分化肝细胞癌。     

<Superscript>68</Superscript>Ga-PSMA-11 PET/CT in primary staging of prostate carcinoma: preliminary results on differences between black and white South-Africans

Purpose

The incidence of prostate cancer is 60% higher and the mortality rate is two- to three-times greater in black versus white men. We report on differences in ⁶⁸Ga-PSMA-11 PET/CT imaging findings in 77 black South-African (BSAs) and 18 white South-African (WSAs) treatment-naïve primary prostate carcinoma (PPC) patients.

Methods

⁶⁸Ga-PSMA-11 PET/CT imaging findings were compared to histological, biochemical and morphological imaging data. Patients were grouped into three Gleason grade groups (GG), GG 1 (scores 3 + 3 and 3 + 4), GG2 (scores 4 + 3 and 4 + 4) and GG3 (scores 9 and 10), and the PSA difference among the groups was determined. Inter-racial difference in SUVmax of the primary tumor as well as its correlation with serum PSA were also determined.

Results

Ninety-three out of 95 PPC where readily identified on ⁶⁸Ga-PSMA-11 PET/CT imaging. Median PPC SUVmax and serum PSA values proved significantly higher (p = 0.033 and p = 0.003) in GG3 patients (median 16.4 and 180 ng/ml) when compared to GG1 patients (median 9.6 and 25.1 ng/ml) or GG2 patients (median 8.8 and 46.2 ng/ml). SUVmax significantly correlated with serum PSA-values (r = 0.377 (p = 0.0001)). Age, frequency of lymph node involvement and distant metastases, and GGs (p ≥ 0.153) were similar in BSAs and WSAs, both median serum PSA-values as well as SUVmax values proved significantly higher in BSAs when compared to WSAs, respectively, 81.6 ng/ml versus 14.5 ng/ml (p = 0.0001) and 11.9 versus 4.38 (p = 0.004). Moreover, Gleason-score normalized median SUVmax values proved 2.5 times higher in BSAs when compared to WSAs (p = 0.005).

Conclusion

SUVmax values proved significantly related to GG and to be significantly higher in BSAs when compared to WSAs. Also, SUVmax significantly correlated with serum PSA values, which was significantly higher in BSAs when compared with WSAs.

     

Accuracy of PET/CT in characterization of solitary pulmonary lesions.

Characterization of a pulmonary lesion is a well-established indication for metabolic imaging with 18F-FDG. There is extensive literature on the use of PET and CT in the characterization of a solitary pulmonary nodule (SPN). The performance of dual-modality imaging with PET/CT for characterizing SPNs was investigated in a clinical referral setting. METHODS: We performed a retrospective study involving patients referred for SPN characterization with PET/CT between September 2002 and June 2004, for whom a pathologic diagnosis was available. The group consisted of 12 men and 30 women whose age ranged from 35 to 84 y (mean age +/- SD, 67 +/- 11 y). A dual-slice CT/lutetium oxyorthosilicate PET system was used for imaging. CT images were acquired without intravenous contrast. Blinded interpretation was performed by 1 chest radiologist for CT and 2 nuclear medicine physicians for PET. PET/CT images were read in consensus. Lesions were analyzed by location, texture, axial dimension, and metabolic activity and visually scored on a 5-point scale from benign to malignant; the maximum standardized uptake value (SUVmax) was measured. RESULTS: Lesion diameter varied from 7 to 30 mm (mean +/- SD, 15 +/- 6 mm). The SUVmax ranged from 0.5 to 17.2 (mean +/- SD, 3.0 +/- 3.0). SUVmax corrected for lean body mass was 0.4-12.1 (mean +/- SD, 2.1 +/- 2.0). Comparison of CT versus PET versus PET/CT yielded accuracies of 74%, 74%, and 93%, respectively. PET and CT correctly characterized 31 and PET/CT correctly characterized 39 of the 42 lesions as malignant or benign. The sensitivity and specificity for CT, PET, and PET/CT was 93%/31%, 69%/85%, and 97%/85%, respectively. There were significant differences (P < 0.05) between PET/CT and PET for accuracy, sensitivity, and specificity. Accuracy did not improve by quantitative analysis using an SUVmax cutoff of 2.0 for malignancy. Lean body mass correction of the SUVmax did not change accuracy. CONCLUSION: PET/CT demonstrates an excellent performance in classifying SPNs as benign or malignant. The combination of anatomic and metabolic imaging is synergistic by maintaining the sensitivity of CT and the specificity of PET, resulting in an overall significantly improved accuracy. Visual interpretation is sufficient for characterizing an SPN. Quantitative analysis does not improve accuracy of PET/CT for SPN characterization.     

11C-胆碱PET/CT显像在前列腺良恶性病变鉴别诊断中的应用

目的 探讨11C-胆碱PET/CT显像在前列腺良恶性病变鉴别诊断中的作用.方法 前列腺病变患者45例,按体重静脉注射7.4 MBq/kg 11C-胆碱5 min后行仰卧位盆腔PET/CT显像,可疑转移患者行全身显像.测量前列腺病灶(靶)及肌肉(非靶)组织的最高标准摄取值(SUVmax),并计算其比值(P/M).结果 病理检查证实前列腺良性病变27例,前列腺癌18例.前列腺良恶性病变的P/M比值间差异有显著性(1.87±1.21与4.02±1.88,t=2.07,P＜0.01).以P/M比值＞2.32为标准,11C-胆碱PET/CT显像诊断前列腺癌的灵敏度为88.89%,特异性为88.89%,阴性预测值为92.31%.结论 11C-胆碱PET/CT显像是一种诊断前列腺癌较好的无创性检查方法;P/M比值比SUV能更好鉴别前列腺良恶性病变.     

Clinical performance of <Superscript>68</Superscript>Ga-PSMA-11 PET/MRI for the detection of recurrent prostate cancer following radical prostatectomy

Purpose

Sensitive visualization of recurrent prostate cancer foci is a challenge in patients with early biochemical recurrence (EBR). The recently established ⁶⁸Ga-PSMA-11 PET/CT has significantly improved the detection rate with published values of up to 55% for patients with a serum PSA concentration between 0.2–0.5 ng/mL. The increased soft tissue contrast in the pelvis using simultaneous ⁶⁸Ga-PSMA-11 PET/MRI might further improve the detection rate in patients with EBR and low PSA values over PET/CT.

Methods

We retrospectively analyzed a cohort of 56 consecutive patients who underwent a ⁶⁸Ga-PSMA-11 PET/MRI for biochemical recurrence in our institution between April and December 2016 with three readers. Median PSA level was 0.99 ng/mL (interquartile range: 3.1 ng/mL). Detection of PSMA-positive lesions within the prostate fossa, local and distant lymph nodes, bones, or visceral organs was recorded. Agreement among observers was evaluated with Fleiss’s kappa (k).

Results

Overall, in 44 of 56 patients (78.6%) PSMA-positive lesions were detected. In four of nine patients (44.4%) with a PSA < 0.2 ng/mL, suspicious lesions were detected (two pelvic and one paraaortic lymph nodes, and two bone metastases). In eight of 11 patients (72.7%) with a PSA between 0.2 and < 0.5 ng/mL, suspicious lesions were detected (two local recurrences, six lymph nodes, and one bone metastasis). Five out of 20 patients with a PSA < 0.5 ng/mL had extrapelvic disease. In 12 of 15 patients (80.0%) with a PSA between 0.5 and < 2.0 ng/mL, suspicious lesions were detected (four local recurrences, nine lymph nodes, and four bone metastases). In 20 of 21 patients (95.2%) with a PSA >2.0 ng/mL, suspicious lesions were detected. The overall interreader agreement for cancer detection was excellent (κ = 0.796, CI 0.645–0.947).

Conclusions

Our data show that ⁶⁸Ga-PSMA-11 PET/MRI has a high detection rate for recurrent prostate cancer even at very low PSA levels <0.5 ng/mL. Furthermore, even at those low levels extrapelvic disease can be localized in 25% of the cases and local recurrence alone is seen only in 10%.

     

Metastatic urinary bladder paraganglioma on Ga-68 DOTATATE PET/CT

Paragangliomas are extra-adrenal catecholamine-secreting neuroendocrine tumors that can present with adrenergic signs and symptoms. The urinary bladder is a rare location for a paraganglioma, and these tumors must be distinguished from other more common bladder neoplasms. In this case report, we discuss a 59 year-old woman who initially presented with tachycardia, palpitations, chest tightness, shortness of breath, and weight loss. Laboratory evaluation showed significantly elevated catecholamines in the plasma and urine. A CT (Computed Tomography) scan of the abdomen and pelvis revealed an enhancing mass arising from the urinary bladder and an enlarged right pelvic lymph node. A follow up Ga-68 DOTATATE PET/CT (Positron Emission Tomography and/or Computed Tomography) showed increased uptake in the primary bladder mass, right pelvic lymph node, numerous skeletal lesions, and pulmonary nodules, consistent with metastatic paraganglioma of the urinary bladder. This case report demonstrates the radiological findings of metastatic urinary bladder paraganglioma and highlights the importance of skull base to mid-thigh PET/CT using Ga-68 DOTATATE. It is crucial for the radiologist to be familiar with the characteristics of urinary bladder paragangliomas and identify these tumors on imaging to allow prompt initiation of surgical resection and/or systemic therapy.     

Local recurrence of prostate cancer after radical prostatectomy is at risk to be missed in <Superscript>68</Superscript>Ga-PSMA-11-PET of PET/CT and PET/MRI: comparison with mpMRI integrated in simultaneous PET/MRI

Purpose

The positron emission tomography (PET) tracer ⁶⁸Ga-PSMA-11, targeting the prostate-specific membrane antigen (PSMA), is rapidly excreted into the urinary tract. This leads to significant radioactivity in the bladder, which may limit the PET-detection of local recurrence (LR) of prostate cancer (PC) after radical prostatectomy (RP), developing in close proximity to the bladder. Here, we analyze if there is additional value of multi-parametric magnetic resonance imaging (mpMRI) compared to the ⁶⁸Ga-PSMA-11-PET-component of PET/CT or PET/MRI to detect LR.

Methods

One hundred and nineteen patients with biochemical recurrence after prior RP underwent both hybrid ⁶⁸Ga-PSMA-11-PET/CT_low-dose (1 h p.i.) and -PET/MRI (2-3 h p.i.) including a mpMRI protocol of the prostatic bed. The comparison of both methods was restricted to the abdomen with focus on LR (McNemar). Bladder-LR distance and recurrence size were measured in axial T2w-TSE. A logistic regression was performed to determine the influence of these variables on detectability in ⁶⁸Ga-PSMA-11-PET. Standardized-uptake-value (SUV_mean) quantification of LR was performed.

Results

There were 93/119 patients that had at least one pathologic finding. In addition, 18/119 Patients (15.1%) were diagnosed with a LR in mpMRI of PET/MRI but only nine were PET-positive in PET/CT and PET/MRI. This mismatch was statistically significant (p?=?0.004). Detection of LR using the PET-component was significantly influenced by proximity to the bladder (p?=?0.028). The PET-pattern of LR-uptake was classified into three types (1): separated from bladder; (2): fuses with bladder, and (3): obliterated by bladder). The size of LRs did not affect PET-detectability (p?=?0.84), mean size was 1.7?±?0.69 cm long axis, 1.2?±?0.46 cm short-axis. SUV_mean in nine men was 8.7?±?3.7 (PET/CT) and 7.0?±?4.2 (PET/MRI) but could not be quantified in the remaining nine cases (obliterated by bladder).

Conclusion

The present study demonstrates additional value of hybrid ⁶⁸Ga-PSMA-11-PET/MRI by gaining complementary diagnostic information compared to ^{the 68}Ga-PSMA-11-PET/CT_low-dose for patients with LR of PC.