Lost in space(s): Multimodal neuroimaging of disorientation along the Alzheimer's disease continuum

Orientation is a fundamental cognitive faculty and the bedrock of the neurologic examination. Orientation is defined as the alignment between an individual's internal representation and the external world in the spatial, temporal, and social domains. While spatial disorientation is a recognized hallmark of Alzheimer's disease (AD), little is known about disorientation beyond space in AD. This study aimed to explore disorientation in spatial, temporal, and social domains along the AD continuum. Fifty-one participants along the AD continuum performed an ecological orientation task in the spatial, temporal, and social domains while undergoing functional MRI. Disorientation in AD followed a three-way association between orientation domain, brain region, and disease stage. Specifically, patients with early amnestic mild cognitive impairment exhibited spatio-temporal disorientation and reduced brain activity in temporoparietal regions, while patients with AD dementia showed additional social disorientation and reduced brain activity in frontoparietal regions. Furthermore, patterns of hypoactivation overlapped different subnetworks of the default mode network, patterns of fluorodeoxyglucose hypometabolism, and cortical atrophy characteristic of AD. Our results suggest that AD may encompass a disorder of orientation, characterized by a biphasic process manifesting as early spatio-temporal and late social disorientation. As such, disorientation may offer a unique window into the clinicopathological progression of AD. SIGNIFICANCE STATEMENT: Despite extensive research into Alzheimer's disease (AD), its core cognitive deficit remains a matter of debate. In this study, we investigated whether orientation, defined as the ability to align internal representations with the external world in spatial, temporal, and social domains, constitutes a core cognitive deficit in AD. To do so, we used PET-fMRI imaging to collect behavioral, functional, and metabolic data from 51 participants along the AD continuum. Our findings suggest that AD may constitute a disorder of orientation, characterized by an early spatio-temporal disorientation and followed by late social disorientation, manifesting in task-evoked and neurodegenerative changes. We propose that a profile of disorientation across multiple domains offers a unique window into the progression of AD and as such could greatly benefit disease diagnosis, monitoring, and evaluation of treatment response.

Simultaneous multislice diffusion-weighted imaging versus standard diffusion-weighted imaging in whole-body PET/MRI

OBJECTIVE

To compare standard (STD-DWI) single-shot echo-planar imaging DWI and simultaneous multislice (SMS) DWI during whole-body positron emission tomography (PET)/MRI regarding acquisition time, image quality, and lesion detection.

METHODS

Eighty-three adults (47 females, 57%), median age of 64 years (IQR 52-71), were prospectively enrolled from August 2018 to March 2020. Inclusion criteria were (a) abdominal or pelvic tumors and (b) PET/MRI referral from a clinician. Patients were excluded if whole-body acquisition of STD-DWI and SMS-DWI sequences was not completed. The evaluated sequences were axial STD-DWI at b-values 50-400-800 s/mm2 and the apparent diffusion coefficient (ADC), and axial SMS-DWI at b-values 50-300-800 s/mm2 and ADC, acquired with a 3-T PET/MRI scanner. Three radiologists rated each sequence's quality on a five-point scale. Lesion detection was quantified using the anatomic MRI sequences and PET as the reference standard. Regression models were constructed to quantify the association between all imaging outcomes/scores and sequence type.

RESULTS

The median whole-body STD-DWI acquisition time was 14.8 min (IQR 14.1-16.0) versus 7.0 min (IQR 6.7-7.2) for whole-body SMS-DWI, p < 0.001. SMS-DWI image quality scores were higher than STD-DWI in the abdomen (OR 5.31, 95% CI 2.76-10.22, p < 0.001), but lower in the cervicothoracic junction (OR 0.21, 95% CI 0.10-0.43, p < 0.001). There was no significant difference in the chest, mediastinum, pelvis, and rectum. STD-DWI detected 276/352 (78%) lesions while SMS-DWI located 296/352 (84%, OR 1.46, 95% CI 1.02-2.07, p = 0.038).

CONCLUSIONS

In cancer staging and restaging, SMS-DWI abbreviates acquisition while maintaining or improving the diagnostic yield in most anatomic regions.

KEY POINTS

• Simultaneous multislice diffusion-weighted imaging enables faster whole-body image acquisition. • Simultaneous multislice diffusion-weighted imaging maintains or improves image quality when compared to single-shot echo-planar diffusion-weighted imaging in most anatomical regions. • Simultaneous multislice diffusion-weighted imaging leads to superior lesion detection.

Predictors for spontaneous resolution of classical FUO in patients undergoing PET-CT

Spontaneous resolution is common in patients with classic fever of unknown origin (FUO). Identifying predictors of spontaneous resolution could reduce the usage of unnecessary, invasive tests or empirical therapy, and furthermore reduce patient anxiety. Identify predictors associated with spontaneous resolution of FUO. A single center, retrospective, cohort study. All hospitalized patients who underwent an ^[18F] FDG PET-CT scan for the investigation of classical FUO between 1/2012 and 1/2020 were included. We compared patients with spontaneous resolution of fever and clinical symptoms, to those who were diagnosed with a specific etiology of FUO (subdivided to infectious diseases, non-infectious inflammatory diseases (NIID), and malignancies). Epidemiologic characteristics as well as laboratory and PETCT study results were compared. Variables that were found to be associated with spontaneous resolution of FUO on univariate analysis (p < 0.1) were entered into a multivariable regression analysis. The results are reported as odds ratios (OR) and 95% confidence intervals (CI). A total of 303 patients were hospitalized for the investigation of classical FUO and underwent complete assessment. Fever resolved without a diagnosis in 84/303 patients (28%). Variables that were associated with spontaneous resolution of FUO on multivariable analysis included: no anemia, no hypoalbuminemia and no pathological FDG uptake on PET-CT. In 17.8% (15/84) of studies, PET-CT yielded false-positive results that led to additional unnecessary, invasive investigation. Patients without anemia or hypoalbuminemia, and those without uptake on PET-CT are more likely to have spontaneous resolution of classical FUO.

The role of additional chemotherapy prior to autologous HCT in patients with relapse/refractory DLBCL in partial remission-A retrospective multicenter study

OBJECTIVES

To evaluate the role of additional chemotherapy before autologous hematopoietic cell transplantation (HCT) in patients with relapse/refractory diffuse large B-cell lymphoma (DLBCL) who achieve partial remission following first salvage therapy.

METHODS

We conducted a multicenter retrospective study of all adult patients with DLBCL who underwent HCT between 2008 and 2020 and achieved partial response (PR) after the first salvage and were either referred directly to HCT (n = 47) or received additional salvage therapy before HCT (n = 22).

RESULTS

Post-HCT CR rate and progression-free survival were comparable between the two groups (66% vs. 68%, p = .86 and median not reached vs. 10.2 months [95% confidence interval, CI 7.1-12.3], p = .27, respectively). Median overall survival (OS) and estimated 3-year OS favored patients who were directly referred to HCT (105.8 [95% CI 63-148] months vs. 14.5 [95% CI 0-44] months, p = .035, and 65% [95% CI 51%-75%] vs. 40% [95% CI 21%-53%], p = .035, respectively). In Cox regression model, while International Prognostic Index and primary refractory versus relapse disease did not impact OS, allocation to a second salvage regimen and older age were both associated with inferior survival (hazard ratio [HR] = 2.57 95% CI 1.1-5.8, p = .023 and HR = 1.04 95% CI 0.99-1.2, p = .064, respectively).

CONCLUSIONS

Referring patients with chemotherapy-sensitive disease in PR directly to HCT is associated with better OS compared to those receiving additional lines of treatment.

Lost in space(s): multimodal neuroimaging of disorientation along the Alzheimer's disease continuum

Orientation is a fundamental cognitive faculty, allowing the behaving self to link his/her current state to their internal representations of the external world. Once exclusively linked to knowledge of the current place and present time, in recent years, the concept of orientation has evolved to include processing of social, temporal, and abstract relations. Concordantly with the growing focus on orientation, spatial disorientation has been increasingly recognized as a hallmark symptom of Alzheimer's disease (AD). However, few studies have sought to explore disorientation along the AD continuum beyond the spatial domain. 51 participants along the AD continuum performed an orientation task in the spatial, temporal and social domains. Under functional magnetic resonance imaging (fMRI), participants determined which of two familiar places/events/people is geographically/ chronologically/ socially closer to them, respectively. A series of analyses revealed disorientation along the AD- continuum to follow a three-way association between (1) orientation domain, (2) brain region, and (3) disease stage. Specifically, participants with MCI exhibited impaired spatio-temporal orientation and reduced task-evoked activity in temporoparietal regions, while participants with AD dementia exhibited impaired social orientation and reduced task-evoked activity in frontoparietal regions. Furthermore, these patterns of hypoactivation coincided with Default Mode Network (DMN) sub-networks, with spatio-temporal orientation activation overlapping DMN-C and social orientation with DMN-A. Finally, these patterns of disorientation- associated hypoactivations coincided with patterns of fluorodeoxyglucose (FDG) hypometabolism and cortical atrophy characteristic to AD-dementia. Taken together, our results suggest that AD may constitute a disorder of orientation, characterized by a biphasic process as (1) early spatio-temporal and (2) late social disorientation, concurrently manifesting in task-evoked and neurodegenerative changes in temporoparietal and parieto-frontal brain networks, respectively. We propose that a profile of disorientation across multiple domains offers a unique window into the progression of AD.

Early prediction of residual disease after neoadjuvant chemoradiotherapy and cetuximab for locally advanced esophageal cancer using 18F-FDG PET-CT imaging: a prospective cohort study

Background

Previous studies in locally advanced esophageal cancer (LAEC) suggested that a change in the tumor's metabolic response, i.e., decrease of its interim ¹⁸F-FDG uptake compared with baseline, may predict histopathological response. We evaluated the possible predictive correlation between various PET-CT and histopathological parameters following a neoadjuvant biological-containing chemoradiotherapy (CRT) regimen.

Methods

Patients with resectable LAEC received neoadjuvant cisplatin/5-fluorouracil-based CRT and cetuximab following one cycle of induction chemotherapy and cetuximab. Changes in maximum and mean standardized uptake values (ΔSUV-max and ΔSUV-mean, respectively) and metabolic tumor volume (ΔMTV), measured by PET-CT at baseline and 2 weeks after the onset of treatment, were compared with histopathological findings at surgery. Histopathological response was defined by tumor regression grade (TRG), pathological complete response (pCR) and microscopic or macroscopic residual disease (RD).

Results

Of 18 patients, 13 (72%) with adenocarcinoma (AC) and 5 (28%) with squamous cell carcinoma (SCC), were included. None of the changes in the parameters of PET was associated with pCR; only ΔSUV-mean was associated with TRG in the AC cohort. In contrast, both ΔSUV-mean% and ΔSUV-max% were significantly associated with RD, both in the whole cohort and in the AC cohort. Changes in FDG-uptake predicted RD2 at surgery: only patients with less than 13% decrease in SUV-mean% or less than 29% decrease in SUV-max% had RD2, while all patients with RD0 or RD1 had greater reductions [100% specificity and 100% positive predictive value (PPV)].

Conclusions

Changes in ΔSUV-max and ΔSUV-mean after two weeks of onset of cetuximab-based neoadjuvant chemotherapy for LAEC may predict macroscopic RD but not TRG or pCR at surgery.

Neoadjuvant 177Lu-PSMA-I&T Radionuclide Treatment in Patients with High-risk Prostate Cancer Before Radical Prostatectomy: A Single-arm Phase 1 Trial

BACKGROUND

High-risk localized prostate cancer (HRLPC) has a substantial risk of disease progression despite local treatment. Neoadjuvant systemic therapy before definitive local therapy may improve oncological outcomes by targeting the primary tumor and micrometastatic disease.

OBJECTIVE

To evaluate whether a lutetium-177 prostate-specific membrane antigen radioligand (LuPSMA) can be safely administered to patients with HRLPC before robot-assisted radical prostatectomy (RARP) and to describe immediate oncological outcomes.

DESIGN, SETTING, AND PARTICIPANTS

This was an open-label, single-arm clinical trial. Patients with HRLPC and elevated radioligand uptake on PSMA positron emission tomography/computed tomography were enrolled. Two or three LuPSMA radioligand doses (7.4 GBq) were given at 2-wk intervals. RARP with lymph node dissection was performed 4 wk after the last LuPSMA dose.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The rate of surgical complications, operative parameters, changes in functional and quality-of-life measures, and immediate oncological outcomes (histological findings and biochemical response) were measured. Data were analyzed descriptively.

RESULTS AND LIMITATIONS

Fourteen patients participated (median age 67 yr). Prostate-specific antigen decreased by 17% (interquartile range [IQR] 9-50%) after two LuPSMA doses and 34% (IQR 11-60%) after three doses. Thirteen patients underwent RARP with no identifiable anatomical changes or intraoperative complications. Four patients (30%) had postoperative complications (pneumonia, pulmonary embolism, urinary leak with urinary tract infection). At 3 mo postoperatively, 12 patients (92%) required one pad or less. Final whole-mount pathology showed positive surgical margins (PSMs) in seven patients (53%) and downgrading to International Society of Urological Pathology grade group 3 in three patients (23%). Treatment-related effects included a clear vacuolated cytoplasm and pyknotic nuclei.

CONCLUSIONS

LuPSMA followed by RARP appears to be surgically safe. While oncological outcomes are pending, continence recovery seems to be unaffected by LuPSMA treatment.

PATIENT SUMMARY

We evaluated outcomes for patients with aggressive localized prostate cancer who received treatment with a radioactive agent before surgical removal of their prostate. This approach appears to be safe and feasible, but its therapeutic efficacy is still unknown.

Effect of steroid treatment on the diagnostic yield of baseline 18f-fluorodeoxyglucose positron emission tomography in aggressive B cell lymphoma

Aggressive B cell lymphoma often requires prompt steroid treatment, even before baseline ¹⁸f-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and definitive treatment, to alleviate symptoms or prevent organ damage. Since lymphoma is a steroid-sensitive malignancy, there are concerns that steroids might affect the results of FDG PET/CT and decrease its diagnostic yield. The aim of the current study was to evaluate the effect of steroids administered before baseline PET/CT on the maximum standardized uptake value (SUVmax) and additional PET/CT parameters. Retrospective review of the database in a tertiary medical center yielded 178 patients newly diagnosed with aggressive B cell lymphoma between January 2017 and May 2020 who had an available baseline FDG PET/CT scan. The cohort was divided into patients who received steroids before PET/CT (n = 47) and those who did not (n = 131), and the groups were compared for SUVmax and additional PET/CT parameters. The steroid-treated group had a higher disease stage and lactate dehydrogenase level compared to the steroid-naïve group, with a trend toward a higher international prognostic index. There was no significant between-group difference in SUVmax (P = 0.61). This finding remained consistent across steroid treatment durations and dosage regimens. Further evaluation revealed a significantly larger mean tumor volume and a trend toward a higher tumor metabolic burden in the steroid-treated group, yet no between-group difference in SUV mean or other PET/CT parameters. In this retrospective analysis of patients with aggressive B cell lymphoma, steroid prophase prior to baseline PET/CT did not decrease the diagnostic yield of the scan. However, further studies are required to fully appreciate the impact of steroids on PET CT parameters.

Phase 2 single arm study of nivolumab and ipilimumab (Nivo/Ipi) in previously treated classical Kaposi Sarcoma (cKS)

BACKGROUND

Classical Kaposi Sarcoma (cKS) is a rare HHV8-associated sarcoma with limited treatment options. We evaluated the efficacy and safety of nivolumab in combination with ipilimumab (Nivo/Ipi) in patients with previously treated progressive cKS.

PATIENTS AND METHODS

cKS pts with progressive disease after > 1 lines of systemic therapy and measurable disease by PET/CT and/or physical examination received nivolumab 240mg every two weeks and ipilimumab 1mg/kg every six weeks until progression or toxicity for a maximum of 24 months. The primary endpoint was overall response rate (ORR); secondary endpoints included 6-months progression free survival rate (PFS) and safety. Immune correlates were explored using IHC, DNAseq (596/648 genes) and RNAseq (exome capture transcriptome) of tumor specimens and matched blood.

RESULTS

Eighteen male patients (median age 76.5) were enrolled between April 2018 and Dec 2020. At a median follow up of 24.4 months, ORR by RECIST v1.1 was 87%. Metabolic complete response as assessed by PET CT was observed in 8 of 13 (62%) evaluable patients. 6/13 achieved pathological CR post treatment. In two patients, palliative limb amputation was prevented. Median PFS was not reached. The 6mo and 12m PFS rate was 76.5% and 58.8%, respectively. Only four patients (22%) experienced grade 3-4 adverse events. The most frequent genomic alteration was biallelic copy number loss of FOX1A gene. The majority of tumors carried a low TMB, were microsatellite stable (MSS), MMR proficient, did not express PD-L1 and displayed only low lymphocytic infiltrates, rendering them immunologically "cold".

CONCLUSIONS

This prospectively designed phase II study of nivolumab and ipilimumab demonstrates promising activity of this combination in progressive cKS representing a new treatment option in this population.

Clinical and pathological predictors for FDG-PET/CT avidity in patients with marginal zone lymphoma-a retrospective cohort study

BACKGROUND

The clinical value of FDG-PET/CT for staging and monitoring treatment response in patients with aggressive lymphoma is well established. Conversely, its role in the assessment and management of marginal zone lymphoma (MZL) is less conclusive. We aimed to assess clinical, laboratory, and pathological predictors for FDG uptake in these patients, in an attempt to identify MZL patients whose management will benefit from this imaging modality.

METHODS

In this single-center, retrospective cohort study, we included all adult patients diagnosed with MZL at the Rabin Medical Center between January 2006 and December 2020 who underwent FDG-PET/CT at the time of diagnosis. Primary outcomes were FDG avidity (defined as a visual assessment of at least moderate intensity), SUVmax, and SUVliver. Variables such as advanced clinical stage, primary disease site, hemoglobin level (Hb), platelet count (Plt), serum albumin, LDH level, β-2 microglobulin, and Ki 67 index were evaluated univariate and multivariate analysis using logistic and linear regression models. Association between FDG avidity and progression-free and overall survival was evaluated using Kaplan-Meier curves and Cox regression analysis.

RESULTS

A total of 207 MZL patients were included in this study, 76 of whom (36.7%) had FDG-avid disease. Baseline patients' characteristics such as age, gender, and comorbid conditions were similar between patients with and without significant FDG uptake. In a multivariate logistic regression model, non-gastric MALT (OR 4.2, 95% CI 1.78-10), Ki 67 index ≥ 15% (OR 3.64, 95% CI 1.36-9.76), and elevated LDH level (OR 8.6, 95% CI 3.2-22.8) were all associated with positive FDG avidity. In a multivariate linear regression model, a combination of advanced clinical stage, specific disease subtypes, LDH level, and Ki 67 index predicted the value of SUVmax (P value < 0.001; adjusted R² = 33.8%) and SUVmax/SUVliver (P value < 0.001; adjusted R² = 27%). Baseline FDG avidity was associated to PFS and OS only in univariate analyses.

CONCLUSIONS

In this retrospective cohort study, we present prediction models for positive FDG uptake and SUVmax in MZL patients. These models aim to help clinicians choose patients suitable for incorporation of FDG-PET/CT for staging and monitoring disease and reduce the costs of redundant tests.

Autoimmune and Inflammatory Manifestations Associated with Acute Myeloid Leukemia with Trisomy 8 - Case Series and Review of the Literature

AML can be associated with autoimmune or inflammatory phenomena (AIP) occurring prior, concomitantly or after its diagnosis. Trisomy 8 is one of the most common cytogenetic abnormalities associated with AML. We describe three patients with AML, trisomy 8 and associated AIP and review the known literature on this association. All of our patients had major symptomatic relief when treated with leukemia-directed therapy and corticosteroids. AIP in AML may be an underdiagnosed phenomenon, particularly in patients with trisomy 8.

The yield of F18 FDG PET-CT for the investigation of fever of unknown origin, compared with diagnostic CT

BACKGROUND

18F-Fluoro-2-deoxy-D-glucose (FDG) positron emission tomography, with contrast enhanced CT (PET-CT), is recommended as a first or a second-line imaging method for the evaluation of patients with fever of unknown origin (FUO). We evaluated the yield of PET-CT vs. contrast enhanced CT (alone) for the diagnosis of classical FUO.

METHODS

A single center, 8-year retrospective cohort study. All hospitalized patients who underwent PET-CT for the investigation of classical FUO between 1/2012-1/2020 were included. The final diagnosis, based on clinical, microbiological, radiological and pathological data available at the latest follow-up, at least six months after discharge, was determined. For each case, we determined whether the diagnosis would have been reached based on the CT scan alone, or based on the PET-CT (thus, defining PET-CT as necessary). We compared the overall sensitivity and specificity results for both PET-CT and CT scan. Variables that were found to be significantly associated with PET-CT necessity on univariable analysis were entered into a multivariable logistic regression analysis. The results of the regression model were reported in odds ratios (OR) and 95% confidence intervals (CI).

RESULT

A total of 303 patients with classical FUO were referred for PET-CT. The final diagnoses included infectious diseases in 111/303 patients (36.5%), malignancies in 56/303 patients (18.4%) and non-infectious inflammatory conditions in 52/303 patients (17.1%). FUO resolved without diagnosis in 84/303 patients (28%). The overall sensitivity and specificity of the PET-CT scans were 88.7% and 80.9%, respectively, and for the CT scans were 75.2% and 90.2%, respectively. PET-CT had superior sensitivity vs CT (p=0.00) for all subgroups, with generally decreased specificity than CT for infections and inflammatory conditions. PET-CT was determined as necessary in 26% (79/303) of the patients. Endovascular infection, hematological malignancy and large vessel vasculitis were the only factors associated with PET-CT necessity on multivariable analysis.

CONCLUSIONS

PET-CT offers superior sensitivity with slightly decreased specificity for the diagnosis of classical FUO compared to diagnostic CT. We recommend PET-CT as the imaging modality of choice for patients with classical FUO, when endovascular infection, hematological malignancy or large vessel vasculitis are suspected.

PET/MRI and PET/CT Radiomics in Primary Cervical Cancer: A Pilot Study on the Correlation of Pelvic PET, MRI, and CT Derived Image Features

PURPOSE

To evaluate the correlation of radiomic features in pelvic [2-deoxy-2-18F]fluoro-D-glucose positron emission tomography/magnetic resonance imaging and computed tomography ([¹⁸F]FDG PET/MRI and [¹⁸F]FDG PET/CT) in patients with primary cervical cancer (CCa).

PROCEDURES

Nineteen patients with histologically confirmed primary squamous cell carcinoma of the cervix underwent same-day [¹⁸F]FDG PET/MRI and PET/CT. Two nuclear medicine physicians performed a consensus reading in random order. Free-hand regions of interest covering the primary cervical tumors were drawn on PET, contrast-enhanced pelvic CT, and pelvic MR (T2 weighted and ADC) images. Several basic imaging features, standard uptake values (SUV_mean, SUV_max, and SUV_peak), total lesion glycolysis (TLG), metabolic tumor volume (MTV), and more advanced texture analysis features were calculated. Pearson's correlation test was used to assess the correlation between each pair of features. Features were compared between local and metastatic tumors, and their role in predicting metastasis was evaluated by receiver operating characteristic curves.

RESULTS

For a total of 101 extracted features, 1104/5050 pairs of features showed a significant correlation (ρ ≥ 0.70, p < 0.05). There was a strong correlation between 190/484 PET pairs of features from PET/MRI and PET/CT, 91/418 pairs of CT and PET from PET/CT, 79/418 pairs of T2 and PET from PET/MRI, and 50/418 pairs of ADC and PET from PET/MRI. Significant difference was seen between eight features in local and metastatic tumors including MTV, TLG, and entropy on PET from PET/CT; MTV and TLG on PET from PET/MRI; compactness and entropy on T2; and entropy on ADC images.

CONCLUSIONS

We demonstrated strong correlation of many extracted radiomic features between PET/MRI and PET/CT. Eight radiomic features calculated on PET/CT and PET/MRI were significantly different between local and metastatic CCa. This study paves the way for future studies to evaluate the diagnostic and predictive potential of radiomics that could guide clinicians toward personalized patients care.

Evaluation of the Diagnostic Performance of Positron Emission Tomography/Magnetic Resonance for the Diagnosis of Liver Metastases

OBJECTIVE

The aim of this study was to compare the performance of positron emission tomography (PET)/magnetic resonance (MR) versus stand-alone PET and stand-alone magnetic resonance imaging (MRI) in the detection and characterization of suspected liver metastases.

MATERIALS AND METHODS

This multi-institutional retrospective performance study was approved by the institutional review boards and was Health Insurance Portability and Accountability Act compliant, with waiver of informed consent. Seventy-nine patients with confirmed solid extrahepatic malignancies who underwent upper abdominal PET/MR between February 2017 and June 2018 were included. Where focal hepatic lesions were identified, the likelihood of a diagnosis of a liver metastasis was defined on an ordinal scale for MRI, PET, and PET/MRI by 3 readers: 1 nuclear medicine physician and 2 radiologists. The number of lesions per patient, lesion size, and involved hepatic segments were recorded. Proof of metastases was based on histopathologic correlation or clinical/imaging follow-up. Diagnostic performance was assessed using sensitivity, specificity, positive and negative predictive values, and receiver operator characteristic curve analysis.

RESULTS

A total of 79 patients (53 years, interquartile range, 50-68; 43 men) were included. PET/MR had a sensitivity of 95%, specificity of 97%, positive predictive value of 97%, and negative predictive value of 95%. The sensitivity, specificity, positive predictive value, and negative predictive value of MRI were 88%, 98%, 98%, and 90% and for PET were 83%, 97%, 97%, and 86%, respectively. The areas under the curve for PET/MRI, MRI, and PET were 95%, 92%, and 92%, respectively.

CONCLUSIONS

Contrast-enhanced PET/MR has a higher sensitivity and negative predictive value than either PET or MRI alone in the setting of suspected liver metastases. Fewer lesions were characterized as indeterminate by PET/MR in comparison with PET and MRI. This superior performance could potentially impact treatment and management decisions for patients with suspected liver metastases.

Diagnostic Performance of 68Ga Prostate-specific Membrane Antigen PET/MRI Compared with Multiparametric MRI for Detecting Clinically Significant Prostate Cancer

Background Gallium 68 (⁶⁸Ga) prostate-specific membrane antigen (PSMA) PET/MRI may improve detection of clinically significant prostate cancer (CSPC). Purpose To compare the sensitivity and specificity of ⁶⁸Ga-PSMA PET/MRI with multiparametric MRI for detecting CSPC. Materials and Methods Men with prostate specific antigen levels of 2.5-20 ng/mL prospectively underwent ⁶⁸Ga-PSMA PET/MRI, including multiparametric MRI sequences, between June 2019 and March 2020. Imaging was evaluated independently by two radiologists by using the Prostate Imaging Reporting and Data System (PI-RADS) version 2.1. Sensitivity and specificity for CSPC (International Society of Urological Pathology grade group ≥ 2) were compared for ⁶⁸Ga-PSMA PET/MRI and multiparametric MRI by using the McNemar test. Decision curve analysis compared the net benefit of each imaging strategy. Results Ninety-nine men (median age, 67 years; interquartile range, 62-71 years) were included; 79% (78 of 99) underwent biopsy. CSPC was detected in 32% (25 of 78). For CSPC, specificity was higher for ⁶⁸Ga-PSMA PET/MRI than multiparametric MRI (76% [95% CI: 62, 86] vs 49% [95% CI: 35, 63], respectively; P < .001). Sensitivity was similar (88% [95% CI: 69, 98] vs 92% [95% CI: 74, 99], respectively; P > .99). For PI-RADS 3 lesions, specificity was also higher for ⁶⁸Ga-PSMA PET/MRI than for multiparametric MRI: 86% (95% CI: 73, 95) versus 59% (95% CI: 43, 74), respectively (P = .002). Decision curve analysis showed that biopsies targeted to PSMA uptake increased the net benefit of multiparametric MRI only among PI-RADS 3 lesions. The net benefit of targeted biopsy for a PI-RADS 3 lesion with PSMA uptake was higher across all threshold probabilities over 8%. The net benefit of targeted biopsy was similar for PI-RADS 4 and 5 lesions, regardless of PSMA uptake. Conclusions Gallium 68 prostate-specific membrane antigen PET/MRI improved specificity for clinically significant prostate cancer compared with multiparametric MRI, particularly in Prostate Imaging Reporting and Data System grade 3 lesions. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Williams and Estes in this issue.

The clinical value of the endocarditis team: insights from before and after guidelines implementation strategy

PURPOSE

To evaluate the impact of a multidisciplinary the "Endocarditis Team" (ET) on the course and outcome of infective endocarditis (IE) patients.

METHODS

A retrospective before-after study, including hospitalized patients with definite IE, managed before (01.2013-12.2015) and after (01.2016-07.2019) the introduction of an ET. The primary outcomes were defined as 30-day and 1-year mortality and the secondary as conservative vs. invasive strategy, the interval from clinical suspicion of IE to the performance of echocardiography, utilization of multimodality evaluation, time to an invasive procedure, and the duration of hospitalization.

RESULTS

Study population included 92 pre-ET and 128 post-ET implementation patients. Baseline characteristics were similar. During the post-ET period compared with pre-ET, we found higher rates of abscesses and extra-cardiac emboli (27.8% vs. 16.3%, p = 0.048); and a higher invasive procedures rate, including lead extraction (15.6% vs. 6.5%, p = 0.035) and noncardiac surgeries (14.8% vs. 6.5%, p = 0.05). Patients managed during the post-ET period had reduced short (8.5% vs. 17.4%, p = 0.048) and long-term mortality (Log-rank = 0.001). In multivariate analysis of risk factors for long-term mortality, period (pre- or post-ET) was not found to be significantly associated with the mortality.

CONCLUSION

Establishment of an ET was associated with faster and more intensive evaluation of patients with IE. During the period of an ET activity, mortality rates were reduced compared with the previous period.

Postoperative PET-CT in patients (pts) with pathological stage III colon cancer (CC): Interim results from the first prospective validation study

e15599

Background: A substantial number of pts with pathological stage III CC recur despite the absence of metastatic disease on pre-operative CT. In a previous large retrospective study from our institution on 348 pts, we reported that early postoperative PET-CT modified the staging and management of 13.4% of assumed stage III CC pts. The aim of the current study was to prospectively validate these results. Methods: A prospective, single-center study of pts with pathological stage III CC who underwent early postoperative PET-CT between the years 2013-2021. Results: 83 pts were accrued and 81 (48.1% males, median age 66y) were evaluable for the primary endpoint i.e. PET-CT results. Pathological stage was IIIA, IIIB and IIIC in 7 (8.6%), 56 (69.1%) and 17 (21%) of pts, respectively. Median number of lymph nodes examined and of positive nodes were 17 (range, 9-134) and 2 (range, 0-15), respectively. Post-operative PET-CT findings were significant in 7 pts (8.6%): 4 pts (4.9%) were upstaged to stage IV, 2 (2.5%) were diagnosed with a second primary malignancy, and 1 (1.2%) was both upstaged and diagnosed with another cancer. Three additional pts (3.7%) are currently undergoing evaluation for suspicious PET-CT findings. At a median follow-up of 30.6 months (range, 6.2-92), 13 of the 71 pts with true stage III CC recurred; the estimated 3y disease-free survival rate was 81%. The estimated 5y overall survival rates for the entire cohort and for true stage III pts were 82% and 90%, respectively. Of the 5 pts found to have metastatic disease based on PET-CT findings, one is scheduled to undergo potentially curative surgical removal of a solitary liver metastasis. Conclusions: Interim results from the first prospective study to evaluate the impact of early postoperative PET-CT in pts with pathological stage III CC seem to support earlier retrospective data: the use of PET-CT in this setting changed the staging and management of 8.6% of pts, including the possibility for early detection of potentially curable metastatic disease. Additional data, with more pts and longer follow-up, will be presented at the meeting.

Axillary Lymph Nodes Hypermetabolism After BNT162b2 mRNA COVID-19 Vaccination in Cancer Patients Undergoing 18F-FDG PET/CT: A Cohort Study

PURPOSE

Recognition of the pattern of FDG uptake in hypermetabolic axillary lymph nodes (HALs) and association with recent messenger RNA (mRNA) vaccination are important to prevent patient anxiety and further needless examinations or costly biopsies in cancer patients.

MATERIALS AND METHODS

This study was a retrospective cohort study in a single tertiary care institution. We investigate the occurrence and pattern of HAL on FDG PET/CT scans from 650 consecutive cancer patients with recent BNT162b2 mRNA COVID-19 vaccination.

RESULTS

Between December 20, 2020, and February 8, 2021, 650 patients (351 female patients [54%]; mean age, 68.9 years) had recent mRNA COVID-19 vaccination and an FDG PET/CT scan. HALs were found in 57 (14.5%) of 394 patients (95% confidence interval [CI], 10.9%-18.7%) 12.3 ± 5.9 (1-22) days after dose 1 and in 111 (43.3%) of 256 patients (95% CI, 35.3%-52.2%; P < 0.0001) after 7.5 ± 5.4 (1-22) days after dose 2. There was no difference between dose 1 and dose 2 concerning SUVmax (3.7 ± 1.8 [1.3-11.3] and 4.5 ± 3.9 [1.4-26.3], P = 0.13, respectively), SUVmean (2.1 ± 1.0 [0.7-6.5] and 2.7 ± 2.4 [0.8-17], P = 0.08, respectively), and reactogenicity volume (2.7 ± 2.3 [0.2-11.6] cm3 and 2.7 ± 2.4 [0.2-15.5] cm3, P = 0.98, respectively). There was no difference in number and in size of positive lymph nodes between dose 1 and dose 2: 3.2 ± 2.2 (1-10) and 3.7 ± 2.4 (1-12) (P = 0.18), and 1.4 ± 0.4 cm (0.7-2.5 cm) and 1.5 ± 0.4 cm (0.6-3.2 cm) (P = 0.75), respectively.

CONCLUSIONS

A cluster pattern of hypermetabolic ipsilateral small axillary lymph nodes is common after mRNA COVID-19 vaccination, mainly after the second injection.

Hybrid imaging of the abdomen and pelvis

Accurate imaging is crucial for lesion detection in abdominal organs, for the noninvasive characterization of focal and diffuse abnormalities, and for surgical planning. To accomplish these tasks, several imaging modalities such as multidetector computer tomography (MDCT), magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) are used for abdominal imaging, providing important morphological, functional or metabolic information. More recently, PET/MRI has been gaining attention due to the possibility of combining high-resolution imaging with metabolic imaging. PET/MRI is a novel hybrid imaging technology that in the near future might play a pivotal role in the clinical management of oncologic and inflammatory abdominopelvic diseases. Despite the still limited number of published clinical studies, PET/MRI has been proven to be at least equivalent to PET/CT and to standalone MRI in a variety of oncologic disease. Moreover, in selected and focused clinical studies, it has been proven to outperform current standard of care imaging, for example, in evaluating cholangiocarcinomas, liver metastases, untreated and treated rectal cancer. This has also had an impact on therapeuticmanagement in some studies. Therefore in some institutions, including those of the authors, PET/MRI is becoming the new standard imaging modality in staging treatment-naïve intrahepatic massforming cholangiocarcinomas and prior to complicated hepatic surgery.

Dynamic 68Ga-PSMA-11 PET/CT for the Primary Evaluation of Localized Renal Mass: A Prospective Study

The potential role of prostate-specific membrane antigen (PSMA) PET/CT in non-prostate cancer tumors has shown promising results. We examined the performance of dynamic ⁶⁸Ga-PSMA-11 PET/CT (DPSMA) for the evaluation of localized renal mass. Methods: A prospective case series of patients with a newly diagnosed renal mass who were referred for surgery was examined. DPSMA was performed in a standardized manner before surgery. The final surgical histology served as the standard of reference. PSMA expression in the tumor vasculature was assessed and staining intensity was scored. Tracer uptake and PSMA expression were compared between benign and malignant tissue. Results: Of 29 enhancing renal masses evaluated in 27 patients, 24 (83%) were malignant lesions. The median SUV_mean of benign and malignant lesions was 2.3 (interquartile range [IQR], 2.2-2.7) and 6.8 (IQR, 4.2-10.1), respectively (P = 0.009). Median SUV_max of benign and malignant lesions was 3.8 (IQR, 3.3-4.5) and 9.4 (IQR, 5.4-15.8), respectively (P = 0.015). The median washout coefficient (K ₂) was significantly lower in malignant lesions than in benign lesions (0.17 vs. 0.70, P = 0.02). Positive PSMA staining was found in 20 of 24 malignant lesions and in 2 of 5 benign lesions (P = 0.04). Conclusion: This pilot study demonstrated DPSMA uptake and kinetics in localized renal masses. Increased ⁶⁸Ga-PSMA-11 tracer uptake and intratumoral retention correlate with PSMA expression in malignant renal tumors compared with benign renal masses, supporting further assessment of DPSMA as a potential tool for evaluating localized renal masses.

Leukemic Phase of Histiocytic Sarcoma of the Digestive System: A Rare Manifestation of a Rare Disease

Histiocytic sarcoma (HS) is a rare, malignant, and aggressive subtype of histiocytosis. We present an unusual case of aggressive HS presenting in the gastrointestinal tract and gallbladder that progressed after several lines of chemotherapy with a leukemic phase. We review the clinical, pathological, and molecular characteristics of HS in this case and review the literature on HS involving the digestive system as well as on overt leukemic phase of this disease. HS is often diagnosed at an advanced stage, and mortality is high. We discuss the therapeutic approach to patients with HS. We highlight the role of overexpression and somatic alterations in the RAF-MEK-ERK pathway in the pathogenesis of HS and discuss potential targeted approaches to treat these rare tumors.

Lower tumor volume is associated with increased benefit from immune checkpoint inhibitors in patients with advanced non-small-cell lung cancer

AIM

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment for advanced non-small-cell lung cancer (NSCLC), yet many patients do not benefit from Programmed cell death protein 1 (PD-1) axis inhibitors, emphasizing the need for additional markers for better patient selection. Our aim was to evaluate the association between tumor volume and response to ICI.

METHODS

This retrospective ethically-approved study included all consecutive patients with advanced NSCLC who were evaluated with a fluorodeoxyglucose-positron emission tomography scan, prior to the first administration of a single-agent ICI between 1/2016 and 6/2017. Tumor burden was calculated based on total body metabolic tumor volume and sum of all measurable lesions (SOML).

RESULTS

Median SOML was 88 mm, and was inversely and significantly associated with progression-free survival (PFS) (hazard ratio [HR] 2, CI 1.28-3.37, P = .003) and overall survival (OS) (HR 2.36, CI 1.13-4.94, P = .02). SOML≤80 mm had a significantly longer PFS compared to patients with a SOML≥80 mm (median PFS 9.7 vs 3.7 months, respectively, HR for progression 2.26, CI 1.1-4.5, P = .02). Patients with a SOML≤80 also had longer median OS compared to patients with SOML≥80 (median OS 12 vs 9.8 months, respectively, HR for death 3.1, CI 1.2-8, P = .018).

CONCLUSIONS

Low tumor burden was associated with higher response rates (RR), and better PFS and OS in advanced NSCLC patients treated with ICI. These results may improve the selection of patients for treatment with single-agent ICI, as opposed to the combination with chemotherapy, which might be more appropriate for patients with high tumor burden. Prospective analysis is warranted.

Physiologic and hypermetabolic breast 18-F FDG uptake on PET/CT during lactation

OBJECTIVE

To investigate the patterns of breast cancer-related and lactation-related ¹⁸F-FDG uptake in breasts of lactating patients with pregnancy-associated breast cancer (PABC) and without breast cancer.

METHODS

¹⁸F-FDG-PET/CT datasets of 16 lactating patients with PABC and 16 non-breast cancer lactating patients (controls) were retrospectively evaluated. Uptake was assessed in the tumor and non-affected lactating tissue of the PABC group, and in healthy lactating breasts of the control group, using maximum and mean standardized uptake values (SUVmax and SUVmean, respectively), and breast-SUVmax/liver-SUVmean ratio. Statistical tests were used to evaluate differences and correlations between the groups.

RESULTS

Physiological uptake in non-breast cancer lactating patients' breasts was characteristically high regardless of active malignancy status other than breast cancer (SUVmax = 5.0 ± 1.7, n = 32 breasts). Uptake correlated highly between the two breasts (r = 0.61, p = 0.01), but was not correlated with age or lactation duration (p = 0.24 and p = 0.61, respectively). Among PABC patients, the tumors demonstrated high ¹⁸F-FDG uptake (SUVmax = 7.8 ± 7.2, n = 16), which was 326-643% higher than the mostly low physiological FDG uptake observed in the non-affected lactating parenchyma of these patients (SUVmax = 2.1 ± 1.1). Overall, ¹⁸F-FDG uptake in lactating breasts of PABC patients was significantly decreased by 59% (p < 0.0001) compared with that of lactating controls without breast cancer.

CONCLUSION

¹⁸F-FDG uptake in lactating tissue of PABC patients is markedly lower compared with the characteristically high physiological uptake among lactating patients without breast cancer. Consequently, breast tumors visualized by ¹⁸F-FDG uptake in PET/CT were comfortably depicted on top of the background ¹⁸F-FDG uptake in lactating tissue of PABC patients.

KEY POINTS

• FDG uptake in the breast is characteristically high among lactating patients regardless of the presence of an active malignancy other than breast cancer. • FDG uptake in non-affected lactating breast tissue is significantly lower among PABC patients compared with that in lactating women who do not have breast cancer. • In pregnancy-associated breast cancer patients, ¹⁸F-FDG uptake is markedly increased in the breast tumor compared with uptake in the non-affected lactating tissue, enabling its prompt visualization on PET/CT.

A phase II single-arm study of nivolumab and ipilimumab (Nivo/Ipi) in previously treated classical Kaposi sarcoma (CKS)

11518

Background: CKS is a mesenchymal neoplasm associated with HHV8 infection. Though recombinant INFa is approved for treatment of AIDS-related KS, data is limited regarding the role of immune modulation in CKS therapy. Based on favorable responses in viral-induced cancers, we hypothesized that CTLA-4 and PD-1 blockade can induce tumor regression in CKS. We present pre-planned interim analysis of a phase II study of Nivo/Ipi in previously treated progressive CKS. Methods: CKS pts with progressive disease after > 1 line of systemic therapy and measurable disease received nivolumab 240mg d1,15,28 and ipilimumab 1mg/kg d1 q42 days until progression or toxicity. The primary endpoint was overall response rate (ORR) evaluated clinically, radiologically (RECIST) and metabolically (FDG-PET). Secondary endpoints include 6-months progression free survival rate (PFS) and safety. Exploratory endpoints included PD-L1/MMR by IHC, DNAseq (596 genes)/RNAseq (whole transcriptome) of tumor and matched blood specimens to explore CKS genomic traits and IO correlates: TMB and MSI status, MMR and PD-L1 protein expression, and immune gene transcript expression (PD-1, PD-L1, CTLA-4, and others) (Tempus Labs, Chicago, IL, USA). Results: Fifteen patients were enrolled and evaluable (Apr18-Jan20). Median age 72.5 (61-81), all male. At a median FU of 15.7 mo ORR as per RECIST was 66% (9 pts PR, 1 pt CR, 2 pts SD, 3 pts NE). Clinical ORR was 87% and metabolic ORR was 60%. Median PFS was not reached, 6mo PFS rate was 85% and 1y PFS rate was 75%. The safety profile was as expected with all pts experiencing G1 toxicity, 3 pts with G2 toxicity (1 hepatic, 2 asymptomatic lipase increase) and 2 pts with G3 toxicity (1 colitis, 1 asymptomatic lipase increase). One SAE was reported (TIA considered not related to therapy) and treatment was discontinued in 3 pts. Correlative results are available for 8 pts showing a trend for copy number loss in genes with tumor-suppressive activity (FOXA1, ELF3), no PDL1 expression, low TMB, microsatellite stability, but marked overexpression of CTLA-4, PD-1, PDL-1, CD40, OX40 and LAG3 RNA immune transcripts. Conclusions: The interim analysis of this prospective phase II study of nivolumab and low-dose ipilimumab demonstrates promising activity in progressive CKS, with 66% ORR and a 6mo PFS rate of 85%. Toxicity profile is as expected in this class of drugs. Correlative studies are preliminary, but warrant further investigation into genomic traits and immune gene expression profiles. Clinical trial information: NCT03219671. Clinical trial information: NCT03219671 .

[Hybrid imaging of the abdomen and pelvis. German version]

Accurate imaging is crucial for lesion detection in abdominal organs, for the noninvasive characterization of focal and diffuse abnormalities, and for surgical planning. To accomplish these tasks, several imaging modalities such as multidetector computer tomography (MDCT), magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) are used for abdominal imaging, providing important morphological, functional or metabolic information. More recently, PET/MRI has been gaining attention due to the possibility of combining high-resolution imaging with metabolic imaging. PET/MRI is a novel hybrid imaging technology that in the near future might play a pivotal role in the clinical management of oncologic and inflammatory abdominopelvic diseases. Despite the still limited number of published clinical studies, PET/MRI has been proven to be at least equivalent to PET/CT and to stand-alone MRI in a variety of oncologic disease. Moreover, in selected and focused clinical studies, it has been proven to outperform current standard of care imaging, for example, in evaluating cholangiocarcinomas, liver metastases, untreated and treated rectal cancer. This has also had an impact on therapeutic management in some studies. Therefore in some institutions, including those of the authors, PET/MRI is becoming the new standard imaging modality in staging treatment-naïve intrahepatic mass-forming cholangiocarcinomas and prior to complicated hepatic surgery.

Prostate cancer evaluation using PET quantification in 68Ga-PSMA-11 PET/MR with attenuation correction of bones as a fifth compartment

Background

Tissues with low magnetic resonance (MR) signals, such as bones and lungs differ considerably in their attenuation properties, requiring special considerations for attenuation correction. We evaluated the impact of using the five-compartment segmentation model, which incorporates bones, in ⁶⁸Ga-PSMA-11 PET/MR studies in patients undergoing evaluation for prostate cancer.

Methods

Prostate cancer patients underwent dedicated prostate ⁶⁸Ga-PSMA-11 PET/MR followed by whole-body ⁶⁸Ga-PSMA-11 PET/CT. Coronal µmap images of the pelvis derived from four- and five-compartment segmentation models of magnetic resonance attenuation correction (MRAC) were produced. Standardized uptake values (SUV) calculated by the four and five-compartment MRAC models and by computed tomography attenuation correction (CTAC) were compared and correlated in normal prostate tissue, gluteus muscle, sacrum, intra-prostatic lesions and metastases (i.e., bone lesions and involved lymph nodes), and prostatic lesions to gluteus (L/G) ratio.

Results

Twenty-six patients (mean age 69.4±9.3 years) were included in the study. Twenty-five patients presented for prostate cancer staging and one patient was evaluated for recurrent disease. There was a statistically significant difference between SUVs of the gluteus, sacrum, prostatic lesions and normal prostate tissue measured by the four-compartment vs. the five-compartment MRAC models, with a medium effect size. Very good to good correlation between SUV measured using the four-compartment MRAC model and SUV measured using the five-compartment model were noted in all lesional and non-lesional areas. Very good to good correlation was noted between four-compartment MRAC and CTAC SUVs of prostatic lesions and L/G ratio and between five-compartment MRAC and CTAC SUVs of prostatic lesions, L/G ratio and metastatic lesions.

Conclusions

⁶⁸Ga-PSMA-11 PET/MR using the five-compartment segmentation model affects SUV measurements in prostate lesions and in the normal prostate and therefore patient follow-up studies must be conducted using the same segmentation model.

The Role of 18F-Fluorodeoxyglucose Positron-Emission Tomography/Computed Tomography in the Diagnosis of Postoperative Hardware-Related Spinal Infections

BACKGROUND

Implant-related spinal infections are a surgical complication associated with high morbidity. Due to infection, hardware removal may be necessary, which could lead to pseudarthrosis and the loss of stability and alignment.

OBJECTIVES

To evaluate the accuracy and diagnostic value of 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (18F-FDG PET/CT) in the workup of patients with suspected implant-related infections of the spine and to assess the clinical impact of PET/CT results on the management of these infections.

METHODS

The study included nine consecutive patients with a history of spinal surgery who underwent PET/CT for evaluation of suspected spinal implant related infection. All imaging studies were performed between January 2011 and December 2013. All 18F-FDG PET/CT scans were performed on an 8 slice PET/CT following an 18F-FDG injection. Images were scored both visually and semi-quantitatively by a radiology expert. Results were compared to additional imaging studies when available, which were correlated to clinical and bacteriological findings allowing calculation of sensitivity, specificity and accuracy.

RESULTS

Among the patients, five experienced hardware-related spinal infection. 18F-FDG PET/CT sensitivity was 80%, specificity 100%, and accuracy 88.9%. One scan produced a false negative; however, a second PET/CT scan revealed an infection.

CONCLUSIONS

PET/CT was found to be valuable for the diagnosis of postoperative hardware-related spinal infection, especially when other imaging modalities were uninformative or inconclusive. As such, PET/CT could be useful for management of infection treatment.

Comparison between pelvic PSMA-PET/MR and whole-body PSMA-PET/CT for the initial evaluation of prostate cancer: a proof of concept study

OBJECTIVES

Despite the advantages of prostate-specific membrane antigen (PSMA)-PET/MR over PSMA-PET/CT, its relatively long scanning time and suboptimal PET attenuation correction necessitate careful assessment of the most appropriate setting for this type of study. We assessed lesion agreement between PSMA-PET/MR and PSMA-PET/CT in patients undergoing initial evaluation of prostate cancer.

METHODS

This was a prospective study of consecutive patients with histological biopsy-proven prostate cancer who underwent pelvic PSMA-PET/MR followed by whole-body PSMA-PET/CT. All conspicuous PSMA-avid foci were counted on PSMA-PET/CT and PSMA-PET/MR with CT or MR correlation. Analysis was performed for intra-prostatic lesions, capsular invasion, seminal vesicle involvement and lymph node and bone involvement. Incidental and significant findings seen on PSMA-PET/CT outside the PSMA-PET/MR field of view were also analysed. Agreements between PSMA-PET/CT and PSMA-PET/MR findings were performed using Cohen's kappa test.

RESULTS

Image analysis was performed on 140 patients (mean age, 67.3 ± 8.2 years). Agreement between PSMA PET/CT and PSMA-PET/MR was very good for intra-prostatic PSMA-avid foci (K = 0.85) and pelvic lymph nodes (K = 0.98), good for PSMA-avid bone metastases (K = 0.76) and fair for prostatic capsular invasion (K = 0.25) and seminal vesicle involvement (K = 0.31). Twelve patients (8.5%) had incidental findings and two patients (1.4%) had clinically significant findings.

CONCLUSION

Limited pelvic PSMA-PET/MR has very good agreement with PET/CT regarding PSMA-avid prostatic, regional lymph nodes and bone lesions, and is superior to PET/CT with regard to capsular invasion and seminal vesicle involvement.

KEY POINTS

• Limited pelvic PSMA-PET/MR is superior to whole-body PSMA-PET/CT in detecting extensions of localised disease, mainly due to the high soft tissue resolution of MR. • Limited pelvic PSMA-PET/MR may be useful for initial evaluation of histological biopsy-proven prostate cancer. • Further studies are warranted to evaluate limited pelvic PSMA-PET/MR for screening and active surveillance in selected populations.

A phase II single-arm study of nivolumab and ipilimumab (Nivo/Ipi) in previously treated Classic Kaposi sarcoma (CKS)

11064

Background: CKS is an angioproliferative mesenchymal neoplasm causatively associated with human herpes virus 8 infection. Though recombinant IFNa is approved for treatment of AIDS-related KS, data is limited regarding the role of immune modulation in CKS therapy. Based on favorable responses in viral-induced cancers, we hypothesized that CTLA-4 and PD-1 blockade can induce tumor regression in CKS. We present pre-planned interim analysis of a phase II study of Nivo/Ipi in previously treated progressive CKS (NCT03219671). Methods: CKS pts with progressive disease after ≥ 1 line of systemic therapy and measurable disease by PET/CT and/or physical exam received nivolumab 240mg d1,15,28 and ipilimumab 1mg/kg d1 q42 days until progression or toxicity. The primary endpoint was overall response rate (ORR), secondary endpoints include 6-months progression free survival rate (PFS) and safety. Correlative studies in tumor and serum samples are ongoing using an NGS panel for DNA and RNA and proteomic staining (Tempus Labs Inc). A pre-planned interim analysis was conducted after the first ten enrolled patients for efficacy and toxicity evaluation. Results: Ten patients were enrolled and evaluable between April2018 and February2019. Median age 72 (61-79), all male. At a median FU of 3.1 months (1.5-8.1) ORR was 50% (4 patients PR, 1 patient CR, 5 patients SD). Median PFS was not reached however no progression of disease was documented so far. The safety profile was as expected with all patients experiencing G1 toxicity and four patients with G2 toxicity (1 ALT/AST increase, 2 asymptomatic lipase increase). One SAE was reported (TIA considered not related to therapy) and treatment was discontinued in one patient (G2 LFT increase. maintaining CR 4 months after treatment discontinuation). Correlative results are pending. Conclusions: The interim analysis in this prospectively designed phase II study of nivolumab and low-dose ipilimumab demonstrate promising activity in progressive CKS, with 50% ORR and no events of progression thus far. We expect to report the updated efficacy and correlative data. Clinical trial information: NCT03219671.

Clinical Implications of Incidental Sinonasal Positive FDG Uptake on PET-CT

Objectives

Fluorodeoxyglucose positron emission tomography–computed tomography (FDG PET-CT) has been increasingly used in the past decade. Incidental FDG-avid findings are encountered in these studies, several of which with clinical significance. However, the significance of incidental FDG-avid sinonasal findings has not been studied to date.

Study Design

Retrospective cohort study.

Setting

A single tertiary medical center.

Materials and Methods

The medical records were reviewed of patients with incidental sinonasal positive FDG uptake between 2007 and 2016 who referred for further otolaryngological diagnostic workup.

Results

A total of 26 patients were identified, all of whom underwent a diagnostic surgical procedure. Histopathology revealed chronic inflammation (n = 12, 46.1%), malignancy (n = 7, 26.9%), inverted papilloma (n = 4, 15.5%), and fungal infections (n = 3, 11.5%). A unilateral maxillary sinus with FDG uptake was documented for 16 (61.5%) patients. CT evidence of bilateral disease and mucosal or sinus wall thickening correlated with inflammatory disease.

Conclusions

Incidental lesions with positive FDG uptake in the sinonasal cavities are at a high risk (40%) of being neoplastic. A diagnostic biopsy is advocated in these cases.

FDG-PET/CT for diagnosis and follow-up of necrotizing (malignant) external otitis

OBJECTIVE

Imaging is important for the diagnosis and follow-up of necrotizing external otitis (NEO). The best imaging modality is controversy. To suggest 2-deoxy-2-[fluorine-18] fluoro-D-glucose-positron emission tomography/computed tomography (18F-FDG-PET/CT) as an alternative to technetium-99m and gallium-67 scans for diagnosis and assessment of response to treatment for patients with NEO.

STUDY DESIGN

Case series.

METHODS

Tertiary referral center. From 2013 through 2017, 12 patients were diagnosed with NEO based on clinical features and positive FDG uptake within the temporal bone on PET/CT. Mean age was 74 ± 11.5; 83% of the patients were male; and 83% had diabetes.

RESULTS

PET/CT scans were reviewed independently by two nuclear medicine specialists. Imaging located osteomyelitis in external ear canal, mastoid, temporomandibular joint, and nasopharyngeal region (100%, 50%, 16%, 8%, respectively). Mean follow-up was 16 months. Eight patients (67%) underwent a second PET/CT scan after active otitis resolved and after at least 6 weeks of antibiotic treatment. The scan demonstrated no or substantially reduced FDG uptake and treatment was stopped. The patients had no NEO symptoms at the end of follow-up. One patient had significant uptake, and antibiotic treatment was continued until a third scan demonstrated no FDG uptake. Two patients died before the second PET/CT, and two were lost to follow-up.

CONCLUSION

18F-FDG-PET/CT is a reliable imaging modality for diagnosis, disease localization, and decision making regarding treatment cessation. 18F-FDG-PET/CT should be considered as the imaging modality of choice for initial diagnosis and follow-up in NEO patients. Larger, controlled studies are warranted.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:961-966, 2019.

Baseline 18F-FDG PET/CT as predictor of the pathological response to neoadjuvant therapy in esophageal cancer: A retrospective study

The type of pathological response to neoadjuvant chemoradiation in patients with locally advanced esophageal cancer predicts overall survival (OS).We aimed to assess early 18F-FDG positron emission tomography/computed tomography parameters in predicting the pathological response to neoadjuvant treatment.The cohort included consecutive patients with locally advanced esophageal cancer who underwent baseline 18F-FDG positron emission tomography/computed tomography between September 2006 and February 2015. Positron emission tomography variables of maximum and average standardized uptake values (SUVmax, SUVaverage), metabolic tumor volume (MTV), and total lesion glycolysis were recorded in addition to computed tomography volume. MTV was calculated using cut-off values of 42%, 50% and 60% (MTV 0.42, 0.5, and 0.6) of the tumoral SUVmax. Receiver operating characteristic (ROC) analysis was used to determine sensitivity and specificity.Sixty-one patients (44 male, 17 female) fulfilled the inclusion criteria. Only MTV values of 13.6 mL (MTV 0.42) and 7.4 mL (MTV 0.5) remained significant on ROC analysis, with an area under the curve of 0.690 (confidence interval 0.557-0.823, p = .02] and 0.664 (confidence interval 0.527-0.802, P = .048), respectively in differentiating patients with a complete (n = 44) or incomplete (n = 17) pathological response.MTV at presentation is associated with the pathological response to neoadjuvant chemoradiation in patients with locally advanced esophageal cancer.

Spontaneous Regression of Hodgkin Lymphoma: Case Report and Review of the Literature

Spontaneous regression of Hodgkin lymphoma (HL) is a rare event. We describe a 32-year-old woman with spontaneous regression of HL and review the literature. The patient presented with cervical lymphadenopathy and was diagnosed with stage IIA classical HL. The patient refused to receive any treatment for her disease. Positron emission tomography/computed tomography carried out 2 years later showed complete regression of the lymphadenopathy, without pathological uptake of fluorodeoxyglucose. At the last follow-up, 3.5 years after the initial presentation, the patient is with no evidence of disease. During workup for the HL, concomitant papillary thyroid carcinoma was diagnosed, for which the patient refused treatment as well. The thyroid malignancy has remained stable throughout the follow-up.

Early PET-CT in patients with pathological stage III colon cancer may improve their outcome: Results from a large retrospective study

Background

Current staging of pathological stage III colon cancer (CC) is suboptimal; many patients recur despite unremarkable preoperative staging. We previously reported that early postoperative PET‐CT can alter the stage and management of up to 15% of patients with high‐risk stage III CC. This study aimed to determine the role of the test in the general stage III CC population.

Methods

A retrospective study of all consecutive patients with stage III CC who underwent early postoperative PET‐CT between 2005 and 2017.

Results

A total of 342 patients, 166 (48.5%) males, median age 66 years (range, 29‐90), were included. Pathological stage was IIIA, IIIB, and IIIC in 18 (5.3%), 257 (75.1%), and 67 (19.6%) patients, respectively. Median number of positive lymph nodes was 2 (range, 0‐32). PET‐CT results modified the management of 46 patients (13.4%): 37 (10.8%) with overt metastatic disease and 9 (2.6%) with a second primary. The 5‐year disease‐free survival for true stage III patients was 81%. The median overall survival for the entire cohort and for true stage III patients was not reached and was 57.2 months for true stage IV. Of the 37 patients found to be metastatic, 14 (37.8%) underwent curative treatments and 9/14 (64.3%) remain disease‐free, with a median follow‐up of 83.8 months. Predictive factors for upstaging following PET‐CT were identified.

Conclusion

Early postoperative PET‐CT changed the staging and treatment of 13.4% of stage III CC patients and has the potential for early detection of curable metastatic disease. Outcome results are encouraging. Prospective validation is ongoing.

Failure to identify sentinel lymph nodes for malignant melanoma - Outcome after over 10 years median follow up

BACKGROUND

Sentinel lymph node biopsy (SLNB) is routinely performed during surgery for malignant melanoma, using double mapping. Still, in some cases, a sentinel lymph node identified pre-operatively by lymphoscintigraphy is not identified during surgery. We hypothesized that disease specific survival would not be significantly impacted by intra-operative lymph node mapping (IOLM) failure.

METHODS

The patient population study included 1300 malignant melanomas operated on by a single surgical oncologist (H.G.) after sentinel lymph node scintigraphy. Patients were included in the analysis if intra-operative lymph node (IOLM) mapping failed.

RESULTS

Among 1300 patients who underwent surgery for malignant melanoma during the study period and after median follow up of >10 years, 33/36 lymphatic drainage basins with failed sentinel node identification were free of disease. Disease specific survival for the entire group of 33 patients with IOLM failure was 91.0%, which is comparable to previously published disease specific survival for all melanoma patients.

CONCLUSION

We conclude that failure to identify a pre-operatively marked sentinel lymph node by an experienced melanoma surgeon has, generally, no impact on disease specific survival, as demonstrated in this review of a series of surgical melanoma patients.

Dynamic 11C-Choline PET / CT for the primary diagnosis of prostate cancer

OBJECTIVES

To test the ability of dynamic 11C-PET / CT to discriminate cancerous tissue from background tissue in patients with localized prostate cancer.

MATERIALS AND METHODS

Twenty-four consecutive patients with prostate cancer were prospectively evaluated with dynamic 11C-choline PET / CT prior to radical prostatectomy. The PET / CT scan was divided into 18 sequences of 5 seconds each, followed by 9 sequences of 60 seconds each. Whole-mount sections of harvested prostates served as reference standards. Volumes of interest were positioned on the dynamic PET / CT images and the following quantitative variables were calculated: perfusion coefficient (K1), washout constant (K2), area under the curve (AUC) at 175 and 630 seconds, and average and maximum standardized uptake values (SUVavg, and SUVmax). Wilcoxon signed-ranks test was used to compare benign and cancerous areas of the prostate.

RESULTS

Areas of cancerous tissue were characterized by higher SUVavg and SUVmax than areas of benign tissue (3.67 ± 2.7 vs. 2.08 ± 1.3 and 5.91 ± 4.4 vs. 3.71 ± 3.7, respectively, P < 0.001), in addition to a higher K1 (0.95 ± 0.58 vs. 0.43 ± 0.24, P < 0.001) and greater cumulative tracer uptake, represented by the AUC at 175 and 630 seconds (P <0.001). No associations were found between dynamic parameters and preoperative prostate specific antigen level or Gleason score.

CONCLUSIONS

In this pilot study, 11C-choline PET / CT demonstrated increased tracer uptake with higher values of static and dynamic parameters in areas of prostate cancer compared to areas of benign tissue. Larger studies are warranted to validate these results and examine the potential applicability of 11C-choline dynamic PET / CT for the diagnosis of prostate cancer.

The Association of Helicobacter pylori Seropositivity with All-Cause Mortality among Colorectal Cancer Patients Undergoing PET/CT Scans

BACKGROUND

Evidence has been emerging that Helicobacter pylori may also impact colorectal cancer (CRC). Positron emission tomography/computed tomography (PET/CT) imaging can predict overall survival in CRC patients.

OBJECTIVES

To determine a possible association between H. pylori seropositivity and all-cause mortality among CRC patients evaluated by PET/CT scans.

METHODS

This prospective cohort study was comprised of 110 consecutive CRC patients who had undergone a PET/CT evaluation in a tertiary academic medical center. Data included demographics, body mass index (BMI), tumor node metastasis stage at diagnosis, treatment, time from diagnosis to PET/CT, and PET/CT findings. All patients were tested for anti-H. pylori immunoglobulin G (IgG) antibodies and followed for 36 months from the day of the PET/CT scan. Mortality was documented. Univariate and multivariate Cox regression was used to estimate the hazard ratio (HR) of H. pylori serological status.

RESULTS

During the follow-up period, of the 110 CRC patients 41 (37.3%) died and 69 (62.7%) survived. Of the 41 patients, 26 (63.4%) were H. pylori seropositive and 15 (36.6%) were seronegative. Multivariate analysis showed that H. pylori seropositivity was associated with increased mortality (HR 3.46, 95% confidence interval 1.63-7.32), stage IV at diagnosis, metastatic disease found on PET/CT, longer time from diagnosis to PET/CT, lower BMI, and older age.

CONCLUSIONS

Our findings suggest that H. pylori infection may be a risk factor for all-cause mortality among CRC patients who are evaluated by PET/CT. Multicenter studies with larger patient groups are needed to confirm our findings.

Quantitative characterisation of clinically significant intra-prostatic cancer by prostate-specific membrane antigen (PSMA) expression and cell density on PSMA-11

OBJECTIVES

To quantitatively characterize clinically significant intra-prostatic cancer (IPC) by prostate-specific membrane antigen (PSMA) expression and cell density on PSMA-11 positron emission tomography/magnetic resonance (PET/MR).

METHODS

Retrospective study approved by the institutional review board with informed written consent obtained. Patients with a solitary, biopsy-proven prostate cancer, Gleason score (GS) ≥7, presenting for initial evaluation by PET/computerised tomography (PET/CT), underwent early prostate PET/MR immediately after PSMA-11 tracer injection. PET/MR [MRI-based attenuation correction (MRAC)] and PET/CT [CT-based AC (CTAC)] maximal standardised uptake value (SUVmax) and minimal and mean apparent diffusion coefficient (ADCmin, ADCmean; respectively) in normal prostatic tissue (NPT) were compared to IPC area. The relationship between SUVmax, ADCmin and ADCmean measurements was obtained.

RESULTS

Twenty-two patients (mean age 69.5±5.0 years) were included in the analysis. Forty-four prostate areas were evaluated (22 IPC and 22 NPT). Median MRAC SUVmax of NPT was significantly lower than median MRAC SUVmax of IPC (p < 0.0001). Median ADCmin and ADCmean of NPT was significantly higher than median ADCmin and ADCmean of IPC (p < 0.0001). A very good correlation was found between MRAC SUVmax with CTAC SUVmax (rho = -0.843, p < 0.0001). A good inverse relationship was found between MRAC SUVmax and CTAC SUVmax with ADCmin (rho = -0.717, p < 0.0001 and -0.740, p < 0.0001; respectively; Z = 0.22, p = 0.82, NS) and with MRAC SUVmax and ADCmean (rho = -0.737, p < 0.0001).

CONCLUSIONS

PET/MR SUVmax, ADCmin and ADCmean are distinct biomarkers able to differentiate between IPC and NPT in naïve prostate cancer patients with GS ≥ 7.

KEY POINTS

• PSMA PET/MR metrics differentiate between normal and tumoural prostatic tissue. • A multi-parametric approach combining molecular and anatomical information might direct prostate biopsy. • PSMA PET/MR metrics are warranted for radiomics analysis.

Quantitative biomarkers for liver metastases: comparison of MRI diffusion-weighted imaging heterogeneity index and fluorine-18-fluoro-deoxyglucose standardised uptake value in hybrid PET/MR

AIM

To investigate the ability of apparent diffusion coefficient (ADC) heterogeneity index to discriminate liver metastases (LM) from normal-appearing liver (NAL) tissue as compared to common magnetic resonance imaging (MRI) metrics, and to investigate its correlation with 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron-emission tomography (PET) standardised uptake value (SUV).

MATERIALS AND METHODS

Thirty-nine liver metastases in 24 oncology patients (13 women, 11 men; mean age 56±13 years) with proven LM from heterogeneous sources were evaluated on a PET/MRI system. Abdominal sequences included Dixon and diffusion-weighted imaging (DWI) protocols with simultaneous PET. Tissue heterogeneity was calculated using the coefficient of variance (CV) of the ADC, and compared in LM and in NAL tissue of the same volume in an adjacent portion of the liver. The correlations between various ADC measures and PET SUV in distinguishing LM from NAL were evaluated.

RESULTS

A good correlation was found between ADCcv and SUVpeak (r=0.712). Moderate inverse correlation was found between ADCmin and SUVpeak (r=-0.536), and a weak inverse correlation between ADCmean and SUVpeak (r=-0.273). There was a significant difference between LM and NAL when ADCcv (p<0.0001) and ADCmin (p=0.001) were used. Receiver operating characteristic (ROC) analysis of SUV, ADCcv, ADCmin, and ADCmean produced an AUC of 0.989, 0.900, 0.742, and 0.623 respectively.

CONCLUSIONS

The ADCcv index is a potential biomarker of LM with better correlation to ¹⁸F-FDG PET SUVpeak than conventional MRI metrics, and may serve to quantitatively discriminate between LM and NAL.

18F-FDG PET/MR imaging of lymphoma nodal target lesions: Comparison of PET standardized uptake value (SUV) with MR apparent diffusion coefficient (ADC)

To compare positron emission tomography (PET) standardized uptake value (SUV) with magnetic resonance (MR) apparent diffusion coefficient (ADC) of nodal target lesions in patients with F-fluoro-2-deoxyglucose (FDG)-avid lymphomas by simultaneous PET/MR.Patients with histologically proven Hodgkin and non-Hodgkin lymphoma underwent PET/MR limited field of view of FDG-avid target nodal lesions. For PET images, a region of interest (ROI) was drawn around the target nodal lesion and the SUVmax and SUVmean was measured. For MR ADC measurements a ROI was placed over the target nodal lesion on diffusion-weighted imaging (DWI) and ADCmin and ADCmean (mean ADC) values within the ROI were recorded.Thirty-nine patients (19 women, 20 men; 13 patients with Hodgkin lymphoma and 26 with non-Hodgkin lymphoma) were included in the analysis. Sixty-six nodal lesions detected by PET/CT (19 PET-negative and 47 PET-positive) were analyzed by PET/MR. PET/MR quantitative assessments showed that ADCmin and ADCmean were accurate for discriminating positive from negative nodal lymphoma, with an AUC of 0.927 and 0.947, respectively. The ROC curve analysis of ADCmean versus SUVmax and SUVmean was not statistically significant (difference=0.044, P = .08 and difference = 0.045, P = .07; respectively). A substantial inverse association was observed between ADCmean with SUVmean and SUVmax (rho = -0.611; -0.607; P < .0001, respectively). A moderate inverse association was found between ADCmin with SUVmean and SUVmax (rho = -0.529, -0.520; P < .0001, respectively). Interobserver variability of quantitative assessment showed very good agreement for all variables (ICC>0.87).A significant correlation between ADCs and SUVs is found in FDG avid lymphomas. ADCmean is not inferior to PET SUV in discriminating positive and negative nodal lymphomas. Further larger studies are warranted to validate quantitative PET/MR for lymphoma patient management.

Reproducibility and repeatability of same-day two sequential FDG PET/MR and PET/CT

Background

To determine PET/CT and PET/MR reproducibility and PET/MR repeatability of fluorine 18 fluorodeoxyglucose (FDG) uptake measurements in tumors in cancer patients.

Methods

This IRB approved prospective study was performed between October 2015 and February 2016 in consecutive patients who performed same day PET/CT and two sequential PET/MR. Thirty three patients with visible tumors (N = 63) were included. SUV for body weight (SUV) and lean body mass (SUL) were obtained. Volume of interest (VOI) with a threshold of 40% was used and SUV/L’s, metabolic tumor volume (MTV) and tumor to liver ratio (T/L) were calculated. Measurements were plotted in a scattered diagram to visually identify correlation, a regression line was drawn and the equation of the line was calculated. Bland-Altman plots expressed as percentages were constructed to assess the agreement between measurements. The maximal clinically acceptable limits range was defined as ±30%.

Results

Lesional SUV’s, SUL’s and MTV corrected to body weight (BW) and lean body mass (LBM) demonstrated strong positive linear correlation between PET/CT and PET/MR and between two sequential PET/MR. The 95% limits of agreement ranged from -27.7 to 17.5 with a mean of -5.1 and -27.6 to 17.9 with a mean of -4.9 for SUVpeak and SULpeak, respectively for sequential PET/MR. Other PET metrics demonstrated limits range that is above ±30% between PET/CT and PET/MR and between two sequential PET/MR.

Conclusion

PET/MR SUV/L peak has a clinically acceptable repeatability performance and can be used to evaluate the response to treatment.

The value of 18-FDG PET/CT in the diagnosis and management of implant-related infections of the tibia: a case series

BACKGROUND

Positron emission tomography (PET) combined with Computerised Tomography (CT) is gaining ground in clinical settings due to its added value of combined metabolic and anatomical imaging. PET/CT has shown promising results in diagnosing both acute and chronic infection of the axial and appendicular skeleton. PET imaging has an advantage in patients with metallic implants because FDG uptake, in contrast to magnetic resonance imaging (MRI) and standard computed tomography (CT), is not hampered by metallic artifacts. The role of PET/CT in the evaluation of implant-related infections involving the tibia in particular has not been thoroughly studied.

PURPOSE

To investigate the usefulness of 18-FDG PET/CT in the diagnosis and treatment of implant-related infections of the tibia following osteosynthesis.

METHODS

We reviewed 10 patients who underwent internal fixation to the tibia following trauma (4 open fractures, 6 closed fractures) and presented later with clinical signs of a possible implant-related infection. In evaluating the patients we used standard work-up methods (standard radiographs, lab tests) as well as advanced imaging techniques (PET/CT) in order to confirm the diagnosis and decide upon the preferred treatment. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were then calculated for PET/CTs ability to predict presence of infection using intraoperative cultures as the gold standard.

RESULTS

PET/CT validated our working diagnosis 9 out of 10 patients. In particular, it helped distinguish between: infected nonunion (n=4), aseptic nonunion (n=1), soft tissue infection (n=2) and chronic osteomyelitis (n=3). The overall sensitivity and specificity of PET/CT for identifying an osseous infection were 85.7% and 100%, respectively. The PPV and NPV were 100% and 75%, respectively.

CONCLUSION

PET/CT is a promising imaging modality that can aid in the work up of patients with suspected implant-related infections of the tibia following osteosynthesis, and may be used as a supportive measure in clinical decision making.