Nuclear Medicine Specialists Research Articles

The radiology job market in the Netherlands: which subspecialties and other skills are in demand?

ObjectivesTo evaluate the current job market for medical specialists in radiology and nuclear medicine (NM) in the Netherlands.MethodsVacancies posted for radiologists and nuclear medicine physicians in the Netherlands between December 2020 and February 2022 were collected and analyzed.ResultsA total of 157 vacancies (146 for radiologist and 11 for nuclear medicine physicians) were included. The most sought-after subspecialties were all-round (22%), abdominal (19%), and interventional radiology (14%), and 30% of vacancies preferred applicants with additional non-clinical skills (research, teaching, management, information and communications technology (ICT)/artificial intelligence (AI)). Non-academic hospitals significantly more frequently requested all-round radiologists (n = 31) than academic hospitals (n = 1) (p = 0.001), while the distribution of other requested subspecialties was not significantly different between non-academic and academic vacancies. Non-academic hospitals also significantly more frequently requested additional research tasks in their vacancies (n = 35) compared to academic hospitals (n = 4) (p = 0.011). There were non-significant trends for non-academic hospitals more frequently requesting teaching tasks in their vacancies (n =18) than academic hospitals (n = 1) (p = 0.051), and for non-academic hospitals more frequently asking for management skills (n = 11) than academic hospitals (n = 0) (p = 0.075).ConclusionAll-round, abdominal, and interventional radiologists are most in demand on the job market in the Netherlands. All-round radiologists are particularly sought after by non-academic hospitals, whereas nuclear radiologists who completed the Dutch integrated NM and radiology residency seem to be welcomed by hospitals searching for a nuclear medicine specialist. Finally, non-clinical skills (research, teaching, management, ICT/AI) are commonly requested. These data can be useful for residents and developers of training curricula.Clinical relevance statementAn overview of the radiology job market and the requested skills is important for residents, for those who seek work as a radiologist, and for those who are involved in the design and revision of residency programs.Key PointsReview of job vacancies over an extended period of time provides valuable information to residents and feedback to potentially improve radiology and nuclear medicine (NM) residency programs.All-round radiologists are wanted in non-academic hospitals and nuclear radiologists (those who have completed an integrated NM-radiology curriculum) are welcomed by hospitals searching for nuclear medicine specialists in the Netherlands.There is a need to train residents in important non-clinical skills, such as research and teaching, but also management and communications technology/artificial intelligence.

Evaluation of Interstitium by Lymphatic Uptake Method in Chronic Bilateral Lower Extremity Edema.

Symmetrical bilateral lower extremity edema (BLEE) needs to be treated effectively. Finding the cause of this condition increases the success of treatment. Fluid increase in the interstitial space (FIIS) is always present as a cause or a result. Subcutaneously administered nanocolloid is transported by uptake by lymphatic pre-collectors, and this uptake takes place in the interstitium. We aimed to evaluate the interstitium with labeled nanocolloid and contribute to the differential diagnosis in cases with BLEE. Our retrospective study included 74 female patients who underwent lymphoscintigraphy for bilateral lower extremity edema. Technetium 99m (Tc-99m) albumin colloid (nanocolloid), a marked colloidal suspension, was applied subcutaneously to two different areas on the dorsum of both feet with a 26 gauge needle The dose volume administered intradermally is approximately 0.2-0.3 ml, and each injector has 22-25MBq of activity. Siemens E-Cam dual-headed SPECT gamma camera was used for imaging. Dynamic and scanning images were taken with a high-resolution parallel hole collimator. Ankle images were re-evaluated by two nuclear medicine specialists, independent of physical examination and scintigraphy findings. 74 female patients with bilateral lower extremity edema were divided into two groups based on physical examination and lymphoscintigraphy findings. There were 40 and 34 patients in Groups I and II, respectively. In the physical examination, patients in Group I were evaluated as lymphedema, and patients in Group II were evaluated as lipedema. The main lymphatic channel (MLC) was not observed in any of the patients in Group I in the early images, and the MLC was observed at a low level in the late imaging in 12 patients. The sensitivity of the presence of distal collateral flows (DCF) in the presence of significant MLC in early imaging in demonstrating increased fluid in the interstitial space (FIIS) was calculated as 80%, specificity as 80%, PPV 80%, and NPV 84%. While MLC is present in early images, concomitant DCF occurs in cases of lipoedema. The transport of increased lymph fluid production in this group of patients can be covered by the existing MLC. Although MLC is evident, the presence of significant DCF supports the presence of lipedema. It can be used as an important parameter in the diagnosis in early cases where physical examination findings are not evident.

Whole-body low-dose CT can be of value in prostate cancer decision-making: a retrospective study on 601 patients

ObjectivesTo evaluate the diagnostic value of whole-body low-dose computed tomography (CT) to detect bone metastasis in prostate cancer (PCa) patients and its possible utility in therapeutic decision-making. Also, to determine the valuable CT features for lesion characterisation.MethodsThis IRB-approved retrospective study reviewed PCa patients who underwent 68Ga-PSMA PET/CT in our centre from March 2017 to August 2022. Two board-certified radiologists and one nuclear medicine specialist reported all whole-body low-dose CT scans separately, unaware of the 68Ga-PSMA-PET results. The per-lesion and per-patient diagnostic performances were calculated. Also, the significance of CT features was evaluated. Moreover, the inter-observer agreement was analysed. A two-tailed p value < 0.05 was considered significant.ResultsFrom 727 reviewed PCa patients, 601 (mean age = 68.7 ± 8.1) were found to be eligible, including 211 (35.1%) referrals for initial staging and 390 (64.9%) for evaluating the extent of the disease after biochemical recurrence. Per-patient diagnostic analysis for three reviewers showed 81.0–89.4% sensitivity and 96.6–98.5% specificity in detecting osteo-metastasis. It was able to correctly detect high-burden disease based on both CHAARTED and LATITUDE criteria. Regarding the value of underlying CT features, size > 1 cm, ill-defined borders, presence of soft-tissue component, and cortical destruction were statistically in favour of metastasis. Also, Hu > 900 was in favour of benign entities with 93% specificity.ConclusionsAlthough not as accurate as 68Ga-PSMA PET/CT, whole-body low-dose CT might precisely classify PCa patients considering therapeutic decision-making. Additionally, we proposed diagnostic CT features that could help radiologists with better characterisation of the detected lesions.Critical relevance statementThe whole-body low-dose CT can be considered valuable in the clinical decision-making of prostate cancer patients. This modality may obviate performing multiple imaging sessions and high-cost scans in patients diagnosed with the high-burden disease.Graphical abstract

The Comparison of Low and High-Dose Scintigraphy Findings in Patients with Primary Parathyroid Lesions in which Intraoperative Gamma-Probe was Applied.

We aimed to evaluate the effectiveness of high-dose and low-dose use of radioactive material in intraoperative gamma probe application methods in patients diagnosed with primary hyperparathyroidism and planned for surgery. 47 patients with primary hyperparathyroidism underwent minimally-invasive parathyroid surgery (MIS) after preoperative imaging studies consisting of ultrasonography (USG) and sestamibi parathyroid scintigraphy (SPS) showed a possible primary parathyroid lesion (PPL). All patients received Tc-99 sestamibi on day-of-surgery imaging (DOSI) to help with the localization of a primary parathyroid lesion (PPL) via both DOSI and intraoperative gamma probe (IGP). Patients in Group I were administered 20-25 mCi Tc-99m sestamibi (methoxy isobutyl isonitrile) and images were obtained at the 20th and 120th minutes. Patients in Group II were administered 8-10 mCi doses and images were obtained at the 20th and 40th minutes. Two nuclear medicine specialists independently evaluated the images. Lesions in the localizations determined by DOSI and IGP were compared with the histopathological results of these lesions. 47 patients, 35 females, and 12 males were included in the study. The mean age of 28 patients in the first group given the high dose was 54 (41-60), and the mean age was 48 (42-57) in the second group given the low dose (p=0.011). In the group given low-dose radioactive material during intraoperative gamma probe application, the observer's sensitivity, specificity, positive, and negative predictive values for finding pathology were 61.1, 100, 100, and 12.5, respectively. In the group given high-dose radioactive material, the same values were 90.9, 33.3, 50, and 83.3, respectively. While the success of MIS increases with the use of DOSI and IGP in large lesions, the success decreases with the prolongation of the accumulation time of the given dose. In the intraoperative gamma probe technique used in primary hyperparathyroidism patients, the method used with low-dose radioactive material has lower sensitivity but higher specificity in estimating the post-operative pathology compared to the high-dose technique.

Evaluation of Distal Occlusions accompanying Punctal Stenosis using Radionuclide Imaging in patients with Unilateral Epiphora

Objective: Our objective was to evaluate distal occlusions accompanying punctal stenosis, which can lead to impaired nasolacrimal drainage in patients with punctal stenosis, using radionuclide imaging. Material and Methods: Our study enrolled 42 patients who had unilateral punctal stenosis and experienced epiphora on the same side. None of the patients had previously undergone surgical intervention for this condition. Ophthalmological examination results were normal on the unaffected side. Dacryoscintigraphy was performed bilaterally, and specific regions of interest were identified. The scintigraphic images were assessed quantitatively and qualitatively by two nuclear medicine specialists. Evaluation between the nuclear medicine specialists was conducted using the McNemar Bowker test and the Kappa test. Results: Eighty-one percent (34) of the patients were female. The mean age of the patients was 68.23±9.67 years. In patients with punctal stenosis, the punctal area exhibited edematous features. The lacrimal drainage pathway from the punctum was assessed by two nuclear medicine specialists using two different methods. In the visual quantitative evaluation to determine the localization of the stenosis, there was a low to moderate agreement between the two observers (p=0.018, kappa value=0.252). In the quantitative evaluation, there was excellent agreement between the observers (p=0.0001, kappa value=1). Conclusion: Dacryoscintigraphy is preferred as an imaging method due to its non-invasive nature that does not disturb the physiological processes. It offers advantages such as lower radiation exposure and higher patient compliance compared to dacryocystography. However, it should be noted that the anatomical correlation in dacryoscintigraphy is relatively low compared to radiological methods. By incorporating quantitative data into the visual assessment of dacryoscintigraphy, it may be possible to enhance anatomical correlation and improve observer agreement, particularly in patients presenting with a combination of functional and anatomical obstructions.

Whole-Body Magnetic Resonance Imaging (MRI) for Staging Melanoma Patients in Direct Comparison to Computed Tomography (CT): Results from a Prospective Positron Emission Tomography (PET)/CT and PET/MRI Study.

The consideration of radiation exposure is becoming more important in metastatic melanoma due to improved prognoses. The aim of this prospective study was to investigate the diagnostic performance of whole-body (WB) magnetic resonance imaging (MRI) in comparison to computed tomography (CT) with 18F-FDG positron emission tomography (PET)/CT and 18F-PET/MRI together with a follow-up as the reference standard. Between April 2014 and April 2018, a total of 57 patients (25 females, mean age of 64 ± 12 years) underwent WB-PET/CT and WB-PET/MRI on the same day. The CT and MRI scans were independently evaluated by two radiologists who were blinded to the patients' information. The reference standard was evaluated by two nuclear medicine specialists. The findings were categorized into different regions: lymph nodes/soft tissue (I), lungs (II), abdomen/pelvis (III), and bone (IV). A comparative analysis was conducted for all the documented findings. Inter-reader reliability was assessed using Bland-Altman procedures, and McNemar's test was utilized to determine the differences between the readers and the methods. Out of the 57 patients, 50 were diagnosed with metastases in two or more regions, with the majority being found in region I. The accuracies of CT and MRI did not show significant differences, except in region II where CT detected more metastases compared to MRI (0.90 vs. 0.68, p = 0.008). On the other hand, MRI had a higher detection rate in region IV compared to CT (0.89 vs. 0.61, p > 0.05). The level of agreement between the readers varied depending on the number of metastases and the specific region, with the highest agreement observed in region III and the lowest observed in region I. In patients with advanced melanoma, WB-MRI has the potential to serve as an alternative to CT with comparable diagnostic accuracy and confidence across most regions. The observed limited sensitivity for the detection of pulmonary lesions might be improved through dedicated lung imaging sequences.

Evaluation of reconstruction methods and image noise levels concerning visual assessment of simulated liver lesions in 111In-octreotide SPECT imaging

BackgroundEarly cancer detection is crucial for patients’ survival. The image quality in 111In-octreotide SPECT imaging could be improved by using Monte Carlo (MC)-based reconstruction. The aim of this observational study was to determine the detection rate of simulated liver lesions for MC-based ordered subset expectation maximization (OSEM) reconstruction compared to conventional attenuation-corrected OSEM reconstruction.MethodsThirty-seven SPECT/CT examinations with 111In-octreotide were randomly selected. The inclusion criterion was no liver lesions at the time of examination and for the following 3 years. SPECT images of spheres representing lesions were simulated using MC. The raw data of the spheres were added to the raw data of the established healthy patients in 26 of the examinations, and the remaining 11 examinations were not modified. The images were reconstructed using conventional OSEM reconstruction with attenuation correction and post filtering (fAC OSEM) and MC-based OSEM reconstruction without and with post filtering (MC OSEM and fMC OSEM, respectively). The images were visually and blindly evaluated by a nuclear medicine specialist. The criteria evaluated were liver lesion yes or no, including coordinates if yes, with confidence level 1–3. The percentage of detected lesions and accuracy (percentage of correctly classified cases), as well as tumor-to-normal tissue concentration (TNC) ratios and signal-to-noise ratios (SNRs), were evaluated.ResultsThe detection rates were 30.8% for fAC OSEM, 42.3% for fMC OSEM, and 50.0% for MC OSEM. The accuracies were 45.9% for fAC OSEM, 45.9% for fMC OSEM, and 54.1% for MC OSEM. The number of false positives was higher for fMC and MC OSEM. The observer’s confidence level was higher in filtered images than in unfiltered images. TNC ratios were significantly higher, statistically, with MC OSEM and fMC OSEM than with AC OSEM, but SNRs were similar due to higher noise with MC OSEM.ConclusionOne in two lesions were found using MC OSEM versus one in three using conventional reconstruction. TNC ratios were significantly improved, statistically, using MC-based reconstruction, but the noise levels increased and consequently the confidence level of the observer decreased. For further improvements, image noise needs to be suppressed.

Clinical Utility of CT-based Attenuation-correction in Myocardial Perfusion SPECT Imaging.

We aimed to investigate and compare the role of computed tomography (CT)-based attenuation-corrected images (AC) with non-attenuation-corrected images (NAC) obtained by single-photon emission computed tomography/computed tomography (SPECT/CT) myocardial perfusion imaging (MPI). The data of 124 patients who were applied one-day stress-rest Tc-99m sestamibi SPECT/CT MPI and who had coronary angiography (CAG) results within ±3 months were retrospectively reviewed. AC and NAC images were visually evaluated by two nuclear medicine specialists in a consensus. CAG results were used as the reference standard. Specificity, sensitivity, and accuracy were calculated as 66%, 61%, 71%, 79% and 69%, 70% for AC and NAC imaging in the whole group, respectively. There was no statistically significant difference between AC and NAC images for specificity, sensitivity, and accuracy in the male and female subgroups. In the diagnosis of right coronary artery (RCA) disease, CT AC significantly increased the specificity from 87% to 96%. However, in the left anterior descending artery (LAD) region, the specificity was significantly reduced from 95% to 77%. CT-based AC did not significantly contribute to diagnostic performance for increased specificity for the RCA and reduced specificity in the LAD region. Therefore, AC images should always be evaluated side by side with NAC images to benefit from the different advantages of both techniques.

ПЭТ/КТ В ДЕТСКОЙ ОНКОЛОГИИ

Prescriptions for the positron emission tomography-computed tomography (PET-CT) in adult cancer patients are based on the results of multicenter studies, systematic reviews, and meta-analyses. Thus, published international guidelines help nuclear medicine specialists, oncologists and radiologists in determining the most appropriate diagnostic algorithms for each patient with the purpose of selecting the most appropriate treatment as well as allowing the introduction of the new prognostic factors. Compared with adult patients, the use of PET-CT in pediatric oncology is somewhat limited due to the lack of systematic, large multicenter studies and, therefore, precise and clear guidelines. The reasons for the lack of the large studies may be the relatively low incidence of malignant neoplasms in pediatric practice and the fear for the delayed effects of exposure of ionizing radiation on the growing child's body. The purpose of this bibliographical review was to provide a summary of the use and the role of PET-CT in children with the most frequent malignancies.

18F-fluoro-2-deoxy-2-d-glucose PET-CT (FDG PET-CT) in staging of high-risk renal and urothelial bladder cancers (COPPER-T) trial protocol.

Role of 18F-fluoro-2-deoxy-2-d-glucose positron emission tomography-computed tomography (FDG PET-CT) in evaluation of renal cell cancers (RCC) and urinary bladder cancers is not standardized, and the COPPER-T trial, which is a single centre prospective randomized study, was designed to compare it with conventional imaging for staging of clinically localized high risk RCC and urinary bladder carcinoma (Stage T2 and above). There will be two subgroups of patients: RCC and urinary bladder carcinoma. In each of these, the patients will be randomized to either Arm A or Arm B. In each of the arms, each patient will be subjected to diagnostic imaging by FDG PET-CT. The CT scan will be a contrast-enhanced scan like that in conventional staging. A radiologist and nuclear medicine specialist will report the scan independently. The radiologist will not have access to the PET scan sequences and will only review the contrast-enhanced computed tomography (CECT) images. In Arm A, the report of the conventional imaging modality, that is, CECT and bone scan if done, will be reviewed first by the clinician, and based on this report, a management plan will be made. Then, the PET-CT report will be reviewed, and change in the management plan will be noted. New findings or equivocal findings if any in the PET-CT report would be noted. In Arm B, the report of the PET-CT report will be reviewed first by the clinicians, and a management plan will be made. Then, the CECT and/or bone scan reports will be reviewed, and any change in the management plan will be noted. Final analysis of the data after completion of the trial will help in clarifying the role of FDG PET-CT in high risk RCC and transitional cell carcinoma (TCC) of the bladder, its diagnostic accuracy compared with conventional imaging and the impact of using it on patient management.

Predicting 18F-FDG SUVs of metastatic pulmonary nodes from CT images in patients with differentiated thyroid cancer by using a convolutional neural network.

The aim of this study was to predict standard uptake values (SUVs) from computed tomography (CT) images of patients with lung metastases from differentiated thyroid cancer (DTC-LM). We proposed a novel SUVs prediction model using 18-layer Residual Network for generating SUVmax, SUVmean, SUVmin of metastatic pulmonary nodes from CT images of patients with DTC-LM. Nuclear medicine specialists outlined the metastatic pulmonary as primary set. The best model parameters were obtained after five-fold cross-validation on the training and validation set, further evaluated in independent test set. Mean absolute error (MAE), mean squared error (MSE), and mean relative error (MRE) were used to assess the performance of regression task. Specificity, sensitivity, F1 score, positive predictive value, negative predictive value and accuracy were used for classification task. The correlation between predicted and actual SUVs was analyzed. A total of 3407 nodes from 74 patients with DTC-LM were collected in this study. On the independent test set, the average MAE, MSE and MRE was 0.3843, 1.0133, 0.3491 respectively, and the accuracy was 88.26%. Our proposed model achieved high metric scores (MAE=0.3843, MSE=1.0113, MRE=34.91%) compared with other backbones. The predicted SUVmax (R2 = 0.8987), SUVmean (R2 = 0.8346), SUVmin (R2 = 0.7373) were all significantly correlated with actual SUVs. The novel approach proposed in this study provides new ideas for the application of predicting SUVs for metastatic pulmonary nodes in DTC patients.

Diagnostic performance of FDG PET/MRI for cervical lymph node metastasis in patients with clinically N0 head and neck cancer.

Treatment management in cases of head and neck squamous cell cancer (HNSCC) that are clinically negative for lymph node metastases (cN0) is still an important topic of discussion. There is increasing interest in sensitive imaging modalities that can detect the risk of occult metastases at levels below 20%. This study aimed to examine the efficacy of integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) in determining neck nodal metastasis status in cN0 patients with HNSCC. In this retrospective study, 44 patients who underwent neck dissection with the diagnosis of HNSCC between January 2018 and August 2020 were analyzed. Clinical examinations, including ultrasonography, were performed to identify cervical metastases in HNSCC patients with preoperative cN0. A nuclear medicine specialist visually evaluated the MRI, PET, and PET/MRI results. Histopathologically, 86.4% of patients were classified as N0. According to the histopathological results, MRI showed 50% sensitivity, 89.5% specificity, 91.8% negative predictive value (NPV), 42.8% positive predictive value (PPV) and 84% accuracy, while PET showed 83.3% sensitivity, 68.4% specificity, 96.2% NPV, 29.4% PPV and 70.4% accuracy. PET/MRI was more successful in distinguishing pathological N0 and N+ patients (83.3% sensitivity, 92.1% specificity, 97.2% NPV, 62.5% PPV and 90.9% accuracy). PET/MRI is more sensitive and has a higher NPV compared to MRI alone, while its sensitivity was found to be comparable to that of PET. In addition, with its ability to detect pathological N0 patients, PET/MRI may significantly decrease the number of unnecessary neck dissections.

An artificial intelligence framework for the diagnosis of prosthetic joint infection based on 99mTc-MDP dynamic bone scintigraphy.

Dynamic bone scintigraphy (DBS) is the first widely reliable and simple imaging modality in nuclear medicine that can be used to diagnose prosthetic joint infection (PJI). We aimed to apply artificial intelligence to diagnose PJI in patients after total hip or knee arthroplasty (THA or TKA) based on 99mTc-methylene diphosphonate (99mTc-MDP) DBS. A total of 449 patients (255 THAs and 194 TKAs) with a final diagnosis were retrospectively enrolled and analyzed. The dataset was divided into a training and validation set and an independent test set. A customized framework composed of two data preprocessing algorithms and a diagnosis model (dynamic bone scintigraphy effective neural network, DBS-eNet) was compared with mainstream modified classification models and experienced nuclear medicine specialists on corresponding datasets. In the fivefold cross-validation test, diagnostic accuracies of 86.48% for prosthetic knee infection (PKI) and 86.33% for prosthetic hip infection (PHI) were obtained using the proposed framework. On the independent test set, the diagnostic accuracies and AUC values were 87.74% and 0.957 for PKI and 86.36% and 0.906 for PHI, respectively. The customized framework demonstrated better overall diagnostic performance compared to other classification models and showed superiority in diagnosing PKI and consistency in diagnosing PHI compared to specialists. The customized framework can be used to effectively and accurately diagnose PJI based on 99mTc-MDP DBS. The excellent diagnostic performance of this method indicates its potential clinical practical value in the future. • The proposed framework in the current study achieved high diagnostic performance for prosthetic knee infection (PKI) and prosthetic hip infection (PHI) with AUC values of 0.957and 0.906, respectively. • The customized framework demonstrated better overall diagnostic performance compared to other classification models. • Compared to experienced nuclear medicine physicians, the customized framework showed superiority in diagnosing PKI and consistency in diagnosing PHI.

Consequences of early thyroid ultrasound on subsequent tests, morbidity and costs: an explorative analysis of routine health data from German ambulatory care

ObjectivesThis study aims to evaluate whether the use of thyroid ultrasound (US) early in the work-up of suspected thyroid disorders triggers cascade effects of medical procedures and to analyse effects...

Synthesizing and Applying Molecular Targeted Imaging Results in Patients With Prostate Cancer (RADAR VII)

Purpose: Molecular targeted imaging (MTI) is one of the most powerful new tools in the prostate cancer arsenal, but incorporation of MTI results into treatment decision making continues to be a challenge. Guidance is available for clinicians to determine when and how frequently MTI should be used, but clinicians also need to know how MTI results should influence management decisions. Materials and methods: In this review, the Radiographic Assessments for Detection of Advanced Recurrence (RADAR) VII group has developed consensus guidance for the use of MTI in clinical decision making. RADAR VII sought to include all physicians involved in the management of prostate cancer, including urologists, medical oncologists, radiation oncologists, and nuclear medicine specialists. Results: Recommendations were developed for the management of localized, biochemically recurrent, or nonmetastatic castrate-resistant prostate cancer (nmCRPC) by conventional imaging and metastatic disease by MTI. Recommendations were also developed for the treatment of patients with equivocal MTI results. These recommendations are based largely on clinical experience and limited clinical data because of a lack of high-quality, prospective studies regarding the role of MTI in clinical decision making. As such, the RADAR VII group also provides a framework for the incorporation of MTI into ongoing and future clinical trials to support the development of more robust recommendations. Conclusions: We developed several recommendations for the interpretation and application of MTI results for patients with localized disease, biochemical recurrence, and nmCRPC on conventional imaging. These recommendations should be viewed within the context of the limited available evidence and the dynamic nature of prostate cancer research.

Practical RECIP: Visual assessment of response evaluation criteria In PSMA-PET 1.0

To evaluate the accuracy of Response Evaluation Criteria In PSMA-Imaging (RECIP) 1.0 determined by visual reads of nuclear medicine physicians for response evaluation using PSMA-PET/CT in men with mCRPC treated with 177Lu-PSMA radioligand therapy. In total, 124 patients were included in this multicenter retrospective study. All patients received 177Lu-PSMA and underwent PSMA-PET/CT scans at baseline (bPET) and at 12 weeks (iPET). Five nuclear medicine specialists individually interpreted each pair of PSMA-PET/CT scans for responses in PSMA-positive total tumor volume (PSMA-VOL) assessed visually and for occurrence of new lesions. Responses in PSMA-VOL were also assessed quantitatively using semi-automatic segmentation software. Occurrence of new lesions was combined: 1) with visual responses in PSMA-VOL to determine visual RECIP; and 2) with quantitative responses in PSMA-VOL to determine quantitative RECIP. RECIP response classes were dichotomized for differentiation of clinically relevant progressive (PD) vs. non-progressive disease (nPD): RECIP-PD vs. RECIP-nPD. Primary outcome measure was the inter-reader reliability of visual RECIP and agreement between visual vs. quantitative RECIP (by Cohen's κ coefficient). Secondary outcome measure was the prognostic value of visual RECIP (by Cox regression) for overall survival (OS). Based on readers’ majority rule, 41/124 (33%) and 83/124 (67%) patients had visual RECIP-PD and RECIP-nPD, respectively. Agreement among readers in classifying visual RECIP-PD vs. RECIP-nPD was observed in 103 (83%) patients (excellent agreement: κ = 0.81). Agreement between visual vs. quantitative RECIP was observed in 118 (95%) patients (excellent agreement: κ = 0.89). OS was significantly shorter in men with visual RECIP-PD vs. RECIP-nPD (HR 2.55; 95%CI, 1.71–3.81; P < 0.001). The median OS was 8.4 months (95%CI, 7.0–9.8) for patients with RECIP-PD and 16.1 months (95%CI, 13.6–18.5) for patients with RECIP-nPD. Visual RECIP demonstrated excellent inter-reader reliability and excellent agreement with quantitative RECIP calculated using semi-automatic segmentation software. Visual RECIP was prognostic for overall survival of men undergoing 177Lu-PSMA radioligand therapy. RECIP 1.0 evaluated visually by nuclear medicine physicians can be used in practice and clinical trials for response evaluation using PSMA-PET/CT in men with mCRPC.

Renal scintigraphy to predict persistent renal failure after acute kidney injury: an observational study

IntroductionRenal scintigraphy (RS) is occasionally performed to assess the risk of persistent renal failure (PRF) in patients with acute kidney disease (AKD). However, its diagnostic performance has never been assessed.MethodsWe identified all patients with AKD for whom RS was performed in our institution between 2010 and 2017. PRF was defined as persistently low (< 33% of baseline) estimated glomerular filtration rates (eGFR), 1 year after RS. Nuclear medicine specialists reviewed RS data and rated, for each patient, the likelihood of PRF (“PRF score”). We evaluated the performance to predict PRF (area under the ROC curve (AUC)) of RS-derived parameters such as renal accumulation index, accumulation slope, and new parameters derived from serial kidney activity counts. We tested the ability of those parameters to improve a clinical model including hypertension, diabetes, AKI severity and baseline eGFR. Finally, we conducted sensitivity analyses using alternate PRF definitions.ResultsAmong 97 patients included, 57 (59%) fulfilled the criteria for PRF. The PRF score was able to predict PRF with an AUC of 0.63. Similarly, the accumulation index and accumulation slope respective AUCs were 0.64 and 0.63. None of these parameters were able to improve the performance of the clinical model. Among new parameters, the 3rd/2nd minute activity ratio and 3rd/2nd minute activity slope had fair diagnostic performance (AUC 0.72 and 0.74, respectively) and improved the performance of the clinical model. Results were confirmed in sensitivity analyses.ConclusionConventional renal scintigraphy can identify patients at high risk of PRF with a high specificity but a low sensitivity. New parameters, with comparable diagnostic abilities can be obtained within three minutes of injection.Graphical abstract

Evaluation of lung perfusion by using lung perfusion SPECT and lung CT with breathing synchronization software

BackgroundLung perfusion using 99mTc-macroaggregated albumin single-photon emission computed tomography (SPECT) and lung computed tomography (CT) is a useful modality for identifying patients with pulmonary artery embolism. However, conformity between SPECT and CT at the bottom of the lung is generally low. This study aims to investigate the progression of conformity between lung perfusion SPECT and lung CT using a breathing synchronization software.MethodsAmong 95 consecutive patients who underwent lung perfusion SPECT and lung CT within 14 days because of suspected pulmonary embolism between June 2019 and August 2020 in department of cardiovascular medicine, we identified 28 patients (73 ± 10 years) who had normal pulmonary artery on contrast lung CT. We compared lung volumes calculated using lung perfusion SPECT and lung CT as gold standard. Visual conformity between lung SPECT and lung CT was scored 0–4 (0: 0–25%, 1: 25–50%, 2: 50–75%, 3: 75–90%, 4: > 90%) by two specialists in nuclear medicine and assessed.ResultsThe lung volume calculated from lung CT was 3749 ± 788 ml. The lung volume calculated from lung perfusion SPECT without using the breathing synchronization software was 3091 ± 610 ml. There was a significant difference between the lung volume calculated from CT and SPECT without using the breathing synchronization software (P < 0.01). The lung volume calculated from lung perfusion SPECT using the breathing synchronization software was 3435 ± 686 ml, and there was no significant difference between the lung volume calculated from CT and SPECT using the breathing synchronization software. The visual score improved with the use of breathing synchronization software (without software; 1.9 ± 0.6 vs. with software; 3.4 ± 0.7, P < 0.001).ConclusionThis study demonstrated that the breathing synchronization software could improve conformity between lung perfusion SPECT and lung CT.

18-Fluorodeoxyglucose positron emission tomography in the diagnosis of prosthetic aortic graft infection: the difference between open and endovascular repair.

18-Fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) has been reported as useful for diagnosing aortic graft infection. However, 18F-FDG uptake may depend upon various factors including open versus endovascular repair and time from surgery. We aimed to elucidate the factors influencing its uptake and the diagnostic value of 18F-FDG PET/CT after open and endovascular repair. Hospital database of PET/CT (N = 14490) and our departmental database were cross-checked to identify those who underwent 18F-FDG PET/CT after aortic repair. Patient's data were retrieved from the chart. Images were reviewed by 2 nuclear medicine specialists in consensus, and the presence of increased 18F-FDG uptake was recorded. The maximum standardized uptake value (SUV max) was measured. Among the 1112 patients who underwent aortic repair between 2011 and 2022, 71 patients were identified. Eighteen patients underwent 18F-FDG PET/CT for suspected graft infection and the remaining 53 patients for other purposes (malignancy, etc.). Fourteen patients were treated as aortic graft infection. They had significantly higher SUV max than those without graft infection [mean 8.64 (standard deviation 2.78) vs 3.40 (standard deviation 0.84); P < 0.01]. In the non-infected grafts, SUV max was higher early after open surgical repair, while it remained low after endovascular repair. After endovascular aortic repair, a constant cut-off value of 'SUV max = 4.5' seems appropriate for diagnosing graft infection, since it remains low and stable from the early postoperative period. After open surgical repair, it seems acceptable to have 'stepwise cut-off value' depending on the time from surgery.

Prognostic Significance of Interim PET/CT in Follicular Lymphoma Treated with Frontline Chemoimmunotherapy

Introduction: Despite being the prototypical indolent non-Hodgkin lymphoma, follicular lymphoma (FL) is a heterogeneous disease with a subset of patients experiencing early progression or histological transformation and poor overall survival. Upfront identification of these high-risk patients remains an area of unmet need. Interim positron emission tomography/computed tomography (iPET) is commonly used to identify suboptimal response while on therapy but data supporting this practice in FL are limited. We aimed to evaluate the prognostic impact of iPET response assessment using the Deauville 5-point scale (DS) in FL patients treated with frontline chemoimmunotherapy (CIT). Methods: Patients with FL (grade 1-3A) who underwent iPET after 2-4 cycles of frontline CIT at a single academic center from 2008-2020 were identified. Patients treated with prior radiotherapy or rituximab monotherapy were excluded. Baseline, interim and end-of-treatment (EOT) PET scans were re-read by a nuclear medicine specialist using the DS. Progression-free survival (PFS) and overall survival (OS) were estimated with the Kaplan-Meier method and compared with the log-rank test. Cox proportional hazards model was used for multivariate analysis. Results: 143 patients were included. The median age was 64 (range 28-86). Forty patients (28%) had grade 3A FL and 126 patients (88%) had stage 3-4 disease. FLIPI score was low for 20%, intermediate for 34% and high for 46% of patients. The CIT used were R-CVP (68%), BR (17%) or R-CHOP (15%) and 59% of patients received rituximab maintenance. Most iPETs (90%) were performed after 3-4 cycles. iPET DS was 1-2 for 59%, 3 for 13% and 4-5 for 28%. Six patients changed therapy based on progression on iPET; four of them had a confirmed histologic transformation. EOT PET was available for all other 137 patients with EOT DS of 1-2 for 72%, 3 for 4% and 4-5 for 24%. During follow up, 63 patients (44%) relapsed or progressed, including 14 patients (10%) with a biopsy-proven transformation in aggressive lymphoma, and 25 patients (17%) died. Progressive lymphoma was the most common cause of death (n=15; 10 of these were from histologic transformation), followed by other malignancy (n=5, including one case of treatment-related AML), cardiovascular cause (n=3) and one treatment-related mortality (liver failure related to hepatitis B reactivation). With a median follow up of 67 months, the median PFS was 70 months (95% CI 22- 119) and median OS was not reach for the entire cohort with a 2-yr PFS of 70% (95% CI 62-77) and 5-yr OS of 85% (95% CI 77-90). IPET was a significant predictor of PFS and OS with a 2-yr PFS 89% vs 64% vs 35% (p=<0,001) and 5-yr OS of 95% vs 63% vs 75% (p<0,001) for DS 1-2 vs 3 vs 4-5 respectively (figure 1) EOT PET was also a significant predictor of PFS and OS with a 2-yr PFS of 92% vs 80% vs 18% (p<0,001) and a 5-yr OS of 94% vs 75% vs 65% (p<0,001) for DS 1-2 vs 3 vs 4-5 respectively. In the multivariate analysis, adjusting for FLIPI and histological grade at diagnosis, iPET DS of 4-5 was an independent factor for worse PFS (HR 5,1 95% CI 2,9-9,1) and OS (HR 6,6 95% CI 2,3-19,3). Patients with iPET DS 3 had a non-significant worse PFS (HR 1,7 95% CI 0,8-3,8) but a significant worse OS (HR 9 95%CI 2,8-29,5) than those with iPET DS1-2. However, most deaths in patients with iPET DS 3 were not related to the underlying lymphoma. Conclusion: In this cohort of FL patients treated with frontline CIT, an iPET DS of 4-5 was predictive of inferior PFS and OS, independently of FLIPI and initial histological grade. A DS of 3 was seen in few patients and had lower predictive value. Whether outcomes can be improved by response-adapted therapy remains to be determined and studies are needed to inform optimal care in this setting. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal