Postmortem Minimally Invasive Autopsy in Critically Ill COVID-19 Patients at the Bedside: A Proof-of-Concept Study at the ICU.

BACKGROUND: Economic restrictions and workforce cuts have continually challenged conventional autopsies. Recently, the COVID-19 pandemic has added tissue quality and safety requirements to the investigation of this disease, thereby launching efforts to upgrade autopsy strategies. METHODS: In this proof-of-concept study, we performed bedside ultrasound-guided minimally invasive autopsy (US-MIA) in the ICU of critically ill COVID-19 patients using a structured protocol to obtain non-autolyzed tissue. Biopsies were assessed for their quality (vitality) and length of biopsy (mm) and for diagnosis. The efficiency of the procedure was monitored in five cases by recording the time of each step and safety issues by swabbing personal protective equipment and devices for viral contamination. FINDINGS: Ultrasound examination and tissue procurement required a mean time period of 13 min and 54 min, respectively. A total of 318 multiorgan biopsies were obtained from five patients. Quality and vitality standards were fulfilled, which not only allowed for specific histopathological diagnosis but also the reliable detection of SARS-CoV-2 virions in unexpected organs using electronic microscopy and RNA-expressing techniques. INTERPRETATION: Bedside multidisciplinary US-MIA allows for the fast and efficient acquisition of autolytic-free tissue and offers unappreciated potential to overcome the limitations of research in postmortem studies.

Ultrasound-based "CEUS-Bosniak"classification for cystic renal lesions: an 8-year clinical experience.

PURPOSE: Renal cysts comprise benign and malignant entities. Risk assessment profits from CT/MRI imaging using the Bosniak classification. While Bosniak-IIF, -III, and -IV cover complex cyst variants, Bosniak-IIF and -III stand out due to notorious overestimation. Contrast-enhanced ultrasound (CEUS) is promising to overcome this deficit but warrants standardization. This study addresses the benefits of a combined CEUS and CT/MRI evaluation of renal cysts. The study provides a realistic account of kidney tumor boards' intricacies in trying to validate renal cysts. METHODS: 247 patients were examined over 8 years. CEUS lesions were graded according to CEUS-Bosniak (IIF, III, IV). 55 lesions were resected, CEUS-Bosniak- and CT/MRI-Bosniak-classification were correlated with histopathological diagnosis. Interobserver agreement between the classifications was evaluated statistically. 105 lesions were followed by ultrasound, and change in CEUS-Bosniak-types and lesion size were documented. RESULTS: 146 patients (156 lesions) were included. CEUS classified 67 lesions as CEUS-Bosniak-IIF, 44 as CEUS-Bosniak-III, and 45 as CEUS-Bosniak-IV. Histopathology of 55 resected lesions revealed benign cysts in all CEUS-Bosniak-IIF lesions (2/2), 40% of CEUS-Bosniak-III and 8% of CEUS-Bosniak-IV, whereas malignancy was uncovered in 60% of CEUS-Bosniak-III and 92% of CEUS-Bosniak-IV. Overall, CEUS-Bosniak-types matched CT/MRI-Bosniak types in 58% (fair agreement, κ = 0.28). CEUS-Bosniak resulted in higher stages than CT/MRI-Bosniak (40%). Ultrasound follow-up of 105 lesions detected no relevant differences between CEUS-Bosniak-types concerning cysts size. 99% of lesions showed the same CEUS-Bosniak-type. CONCLUSION: The CEUS-Bosniak classification is an essential tool in clinical practice to differentiate and monitor renal cystic lesions and empowers diagnostic work-up and patient care.

Organ manifestations of COVID-19: what have we learned so far (not only) from autopsies?

The use of autopsies in medicine has been declining. The COVID-19 pandemic has documented and rejuvenated the importance of autopsies as a tool of modern medicine. In this review, we discuss the various autopsy techniques, the applicability of modern analytical methods to understand the pathophysiology of COVID-19, the major pathological organ findings, limitations or current studies, and open questions. This article summarizes published literature and the consented experience of the nationwide network of clinical, neuro-, and forensic pathologists from 27 German autopsy centers with more than 1200 COVID-19 autopsies. The autopsy tissues revealed that SARS-CoV-2 can be found in virtually all human organs and tissues, and the majority of cells. Autopsies have revealed the organ and tissue tropism of SARS-CoV-2, and the morphological features of COVID-19. This is characterized by diffuse alveolar damage, combined with angiocentric disease, which in turn is characterized by endothelial dysfunction, vascular inflammation, (micro-) thrombosis, vasoconstriction, and intussusceptive angiogenesis. These findings explained the increased pulmonary resistance in COVID-19 and supported the recommendations for antithrombotic treatment in COVID-19. In contrast, in extra-respiratory organs, pathological changes are often nonspecific and unclear to which extent these changes are due to direct infection vs. indirect/secondary mechanisms of organ injury, or a combination thereof. Ongoing research using autopsies aims at answering questions on disease mechanisms, e.g., focusing on variants of concern, and future challenges, such as post-COVID conditions. Autopsies are an invaluable tool in medicine and national and international interdisciplinary collaborative autopsy-based research initiatives are essential.

[Practical aspects of COVID-19 autopsies]. / Praktische Aspekte von COVID-19-Obduktionen.

BACKGROUND: The COVID-19 pandemic represents a so far unknown challenge for the medical community. Autopsies are important for studying this disease, but their safety was challenged at the beginning of the pandemic. OBJECTIVES: To determine whether COVID-19 autopsies can be performed under existing legal conditions and which safety standards are required. MATERIALS AND METHODS: The autopsy procedure undertaken in five institutions in Germany, Austria, and Switzerland is detailed with respect to legal and safety standards. RESULTS: In all institutions the autopsies were performed in technically feasible rooms. The personal equipment consisted of functional clothing including a disposable gown and apron, a surgical cap, eye protection, FFP­3 masks, and two pairs of gloves. In four institutions, complete autopsies were performed; in one institution the ultrasound-guided biopsy within the postmortal imaging and biopsy program. The latter does not allow the appreciation of gross organ pathology; however, it is able to retrieve standardized biopsies for diagnostic and research purposes. Several scientific articles in highly ranked journals resulted from these autopsies and allowed deep insights into organ damage and conclusions to better understand the pathomechanisms. Viral RNA was frequently detectable in the COVID-19 deceased, but the issue of infectivity remains unresolved and it is questionable if Ct values are greater than 30. CONCLUSIONS: With appropriate safeguards, autopsies of people who have died from COVID-19 can be performed safely and are highly relevant to medical research.

KLK3 and TMPRSS2 for molecular lymph-node staging in prostate cancer patients undergoing radical prostatectomy.

BACKGROUND: Lymph-node (LN) metastasis in prostate cancer (PC) is a main risk factor for tumor recurrence after radical prostatectomy (RP). Molecular analysis facilitates detection of small-volume LN metastases with higher sensitivity than histopathology. We aimed to prospectively evaluate six candidate gene markers for detection of pelvic LN metastases and to determine their ability to predict biochemical recurrence-free survival (bRFS) in patients treated with RP. METHODS: The expression of kallikrein 2, 3, and 4 (KLK2, KLK3, and KLK4), prostate-specific membrane antigen (PSMA), transmembrane serine protease 2 (TMPRSS2) and transient receptor potential cation channel subfamily M member 8 (TRPM8) was assessed using qPCR. We analyzed LNs from 111 patients (intermediate PC, n = 32 (29%); high-risk PC, n = 79 (71%)) who underwent RP and extended pelvic lymph-node dissection without neoadjuvant treatment. RESULTS: Overall, 2411 LNs were examined by molecular and histopathologic examination. Histopathology detected 69 LN metastases in 28 (25%) patients. KLK2 and KLK3 diagnostically performed best and classified all pN1-patients correctly as molecular node-positive (molN1/pN1). The concordance on LN level was best for KLK3 (96%). KLK2, KLK3, KLK4, PSMA, TMPRSS2, and TRPM8 reclassified 27 (24%), 32 (29%), 29 (26%), 8 (7%), 13 (12%), and 23 (21%) pN0-patients, respectively, as node-positive (pN0/molN1). On multivariable cox regression analysis molecular LN status (molN1 vs. molN0) using KLK3 (HR 4.0, p = 0.04) and TMPRSS2 (HR 5.1, p = 0.02) were independent predictors of bRFS. Median bRFS was shorter in patients with only molecular positive LNs (molN1/pN0) for KLK3 (24 months, p = 0.001) and for TMPRSS2 (12 months, p < 0.001) compared to patients with negative nodes (molN0/pN0) (median bRFS not reached). CONCLUSIONS: For diagnostic purposes, KLK3 showed highest concordance with histopathology for detection of LN metastases in PC patients undergoing RP. For prognostic purposes, KLK3 and TMPRSS2 expression were superior to histopathologic LN status and other transcripts tested for molecular LN status. We suggest a combined KLK3/TMPRSS2 panel as a valuable diagnostic and prognostic tool for molecular LN analysis.

Implementing cell-free DNA of pancreatic cancer patient-derived organoids for personalized oncology.

One of the major challenges in using pancreatic cancer patient-derived organoids (PDOs) in precision oncology is the time from biopsy to functional characterization. This is particularly true for endoscopic ultrasound-guided fine-needle aspiration biopsies, typically resulting in specimens with limited tumor cell yield. Here, we tested conditioned media of individual PDOs for cell-free DNA to detect driver mutations already early on during the expansion process to accelerate the genetic characterization of PDOs as well as subsequent functional testing. Importantly, genetic alterations detected in the PDO supernatant, collected as early as 72 hours after biopsy, recapitulate the mutational profile of the primary tumor, indicating suitability of this approach to subject PDOs to drug testing in a reduced time frame. In addition, we demonstrated that this workflow was practicable, even in patients for whom the amount of tumor material was not sufficient for molecular characterization by established means. Together, our findings demonstrate that generating PDOs from very limited biopsy material permits molecular profiling and drug testing. With our approach, this can be achieved in a rapid and feasible fashion with broad implications in clinical practice.

Defining secure surgical bone margins in head and neck squamous cell carcinomas: The diagnostic impact of intraoperative cytological assessment of bone resection margins compared with preoperative imaging.

BACKGROUND: Imaging provides crucial staging information for treatment planning of head and neck squamous cell carcinomas (HNSCCs). Despite technical progress in imaging techniques, defining the extent of bone involvement preoperatively remains challenging and requires intraoperative information to control for adequate resection. The intraoperative cytological assessment of the bone resection margins (ICAB) provides information whether bone is infiltrated by carcinoma. The aim of this study was to assess the diagnostic value of preoperative imaging compared with ICAB in order to achieve carcinoma-free bone margins. MATERIALS AND METHODS: 108 HNSCC patients underwent preoperative computed tomography (CT), magnetic resonance imaging (MRI) and orthopantomogram (OPG) for staging and surgical planning. Curative resection was planned based on imaging. Intraoperatively, the resection margins were controlled by ICAB. The diagnostic value of preoperative imaging and ICAB was assessed with reference to the histological findings. RESULTS: CT showed a sensitivity of 89.7%, specificity of 63.0%, positive predictive value (PPV) of 85.9%, and negative predictive value (NPV) of 70.8%. MRI revealed a sensitivity of 45.5%, specificity of 66.7%, PPV of 71.4% and NPV of 40.0%. OPG-imaging had a sensitivity of 64.7%, specificity of 76.2%, PPV of 81.5%, NPV 57.1%. In comparison, ICAB provided a sensitivity of 78.6%, specificity of 95.7%, PPV 73.3%, and NPV 96.7%. The accuracy was 82.1%, 52.9%, 69.0%, and 93.5% for CT, MRI, OPG, and ICAB, respectively. CONCLUSION: Preoperative imaging lacks accuracy in defining adequate bone resection margins, compared with ICAB. ICAB supports preoperative imaging and intraoperative frozen sections to improve bone margin control.

Lessons from exome sequencing in prenatally diagnosed heart defects: A basis for prenatal testing.

Congenital heart defects (CHDs) are the most common birth defect with 30%-40% being explained by genetic aberrations. With next generation sequencing becoming widely available, we sought to evaluate the clinical utility of exome sequencing (ES) in prenatally diagnosed CHD. We retrospectively analyzed the diagnostic yield as well as non-conclusive and incidental findings in 30 cases with prenatally diagnosed CHDs using ES, mostly as parent-child trios. A genetic diagnosis was established in 20% (6/30). Non-conclusive results were found in 13% (4/30) and incidental findings in 10% (3/30). There was a phenotypic discrepancy between reported prenatal and postnatal extracardiac findings in 40% (8/20). However, none of these additional, postnatal findings altered the genetic diagnosis. Herein, ES in prenatally diagnosed CHDs results in a comparably high diagnostic yield. There was a significant proportion of incidental findings and variants of unknown significance as well as potentially pathogenic variants in novel disease genes. Such findings can bedevil genetic counseling and decision making for pregnancy termination. Despite the small cohort size, our data serve as a first basis to evaluate the value of prenatal ES in CHD for further studies emerging in the near future.

Discerning the Primary Carcinoma in Malignant Peritoneal and Pleural Effusions Using Imaging Mass Spectrometry-A Feasibility Study.

PURPOSE: Malignant effusions challenge diagnostic accuracy due to cytomorphologic overlaps between various malignant primaries. Workup of this material to establish a correct diagnosis is time consuming and limited by the sparsity of material. In order to circumvent these drawbacks, the use of MALDI imaging MS (IMS) as a diagnostic platform has been explored. EXPERIMENTAL DESIGN: Cytology cell blocks from malignant effusions (serous ovarian carcinoma and several non-ovarian carcinomas including gastric adenocarcinoma) containing at least 30% neoplastic cells are selected for generation of cytology microarrays (CMA). CMA sections are transferred to conductive glass slides, subjected to on-tissue tryptic digestion, and matrix application for MALDI-IMS analysis. RESULTS: Supervised classification analysis identifies serous ovarian carcinomas as the source of malignant effusions with a sensitivity of 85.7% when compared to samples from all other included primary sites. When compared to gastric adenocarcinoma, serous ovarian carcinoma samples can be delineated with a sensitivity of 97.3%. CONCLUSION AND CLINICAL RELEVANCE: These preliminary results highlight that MALDI-IMS allows subtyping of malignant effusions to identify the precise origin of neoplastic cells. While achieving similar results compared to classical approaches such as immunocytology, more material is conserved that will be available for further tests.

Integrated morphologic and molecular analysis of Trichomonas vaginalis, Mycoplasma hominis, and human papillomavirus using cytologic smear preparations.

Pathogenic microbes may colonize the female genital tract via sexual transmission and cause health issues like inflammation or malignancy, summarized as sexually transmitted disease (STD). A major representative of such pathogens is Trichomonas vaginalis (T.v.), whose role in the etiology of cervical cancer remains elusive. Traditional morphologic screening of cervical smears is able to detect T.v., although its identification may be complicated by look-alikes such as degenerated granulocytes and basal cells. In addition, the parasite's endosymbiont Mycoplasma hominis (M.h.) cannot be detected in the Pap test. This investigation was aimed at designing a PCR-based method to detect specific pathogenic germs by using cervical cytology slides to overcome morphologic uncertainty and increase diagnostic accuracy. To test our molecular screening method on T.v., M.h., and HPV in archival smears, we elaborated a multiplex PCR approach based on microdissection. This assay was applied to a minute quantity of starting material which harbored or was suspected to harbor T.v.; the resulting isolated DNA was used for subsequent molecular analyses of T.v., M.h., and HPV. We clarified the diagnosis of genital T.v. infection in 88 and 1.8% of morphologically suspicious and T.v.-negative cases, respectively. We also revealed a tendency of M.h. co-infection in high-risk HPV cases. In conclusion, a microdissection-based approach to detect pathogenic microbes such as T.v., HPV, and M.h. is a molecular tool easy to implement and may help to better understand the interactivity of these germs with respect to pathogenesis.

Molecular Lymph Node Status for Prognostic Stratification of Prostate Cancer Patients Undergoing Radical Prostatectomy with Extended Pelvic Lymph Node Dissection.

Purpose: Molecular lymph node (LN) analysis using quantitative polymerase chain reaction (qPCR) detects LN metastases with higher sensitivity than histopathology. However, the prognostic role of molecular LN status in prostate cancer patients treated with radical prostatectomy (RP) and extended pelvic LN dissection (ePLND) is unclear. To investigate the association of molecular compared with histopathologic LN status with biochemical recurrence.Experimental Design: Patients with intermediate and high-risk prostate cancer were prospectively enrolled and underwent RP with ePLND, including the obturator, internal, external, and the common iliac region. LNs ≥3 mm were bisected and examined by standard histopathology and qPCR for Kallikrein3 (KLK3) expression. Biochemical recurrence was defined by confirmed postoperative PSA > 0.2 ng/mL.Results: In 111 patients, 2,411 of 3,173 removed LNs were examined by both methods. Histopathology detected 68 LN metastases in 28 (25%) patients. Molecular analysis confirmed elevated KLK3 expression in 65 histopathologic LN metastases of all 28 pN1 patients (pN1/molN1) and additionally reclassified 224 histopathologic negative LNs and 32 (29%) pN0 patients as LN-positive (pN0/molN1).At a median follow-up of 48 months, 52 (47%) patients developed biochemical recurrence. Median biochemical recurrence-free survival was 9 months [95% confidence interval (CI), 0.0-20.1] in pN1/molN1 patients, 24 months (95% CI, 1.7-46.3) in pN0/molN1 patients and was not reached in pN0/molN0 patients (P < 0.001). On multivariable Cox regression analysis, molecular LN status [HR 4.1 (95% CI, 1.9-8.8), P < 0.001] but not histopathologic LN status [HR 1.5 (95% CI, 0.8-3.0), P = 0.198] was confirmed as independent predictor of biochemical recurrence.Conclusions: Molecular LN analysis identified pN0 patients with a high risk of biochemical recurrence and provided superior prognostic information in comparison with histopathology alone. Clin Cancer Res; 24(10); 2342-9. ©2018 AACR.

Effects of trastuzumab and afatinib on kinase activity in gastric cancer cell lines.

The molecular mechanism of action of the HER2-targeted antibody trastuzumab is only partially understood, and the direct effects of trastuzumab on the gastric cancer signaling network are unknown. In this study, we compared the molecular effect of trastuzumab and the HER kinase inhibitor afatinib on the receptor tyrosine kinase (RTK) network and the downstream-acting intracellular kinases in gastric cancer cell lines. The molecular effects of trastuzumab and afatinib on the phosphorylation of 49 RTKs and 43 intracellular kinase phosphorylation sites were investigated in three gastric cancer cell lines (NCI-N87, MKN1, and MKN7) using proteome profiling. To evaluate these effects, data were analyzed using mixed models and clustering. Moreover, proliferation assays were performed. Our comprehensive quantitative analysis of kinase activity in gastric cancer cell lines indicates that trastuzumab and afatinib selectively influenced the HER family RTKs. The effects of trastuzumab differed between cell lines, depending on the presence of activated HER2. The effects of trastuzumab monotherapy were not transduced to the intracellular kinase network. Afatinib alone or in combination with trastuzumab influenced HER kinases in all cell lines; that is, the effects of monotherapy and combination therapy were transduced to the intracellular kinase network. These results were confirmed by proliferation analysis. Additionally, the MET-amplified cell line Hs746T was identified as afatinib nonresponder. The dependence of the effect of trastuzumab on the presence of activated HER2 might explain the clinical nonresponse of some patients who are routinely tested for HER2 expression and gene amplification in the clinic but not for HER2 activation. The consistent effects of afatinib on HER RTKs and downstream kinase activation suggest that afatinib might be an effective candidate in the future treatment of patients with gastric cancer irrespective of the presence of activated HER2. However, MET amplification should be taken into account as potential resistance factor.

Prostate-specific membrane antigen cleavage of vitamin B9 stimulates oncogenic signaling through metabotropic glutamate receptors.

Prostate-specific membrane antigen (PSMA) or folate hydrolase 1 (FOLH1) is highly expressed on prostate cancer. Its expression correlates inversely with survival and increases with tumor grade. However, the biological role of PSMA has not been explored, and its role in prostate cancer remained elusive. Filling this gap, we demonstrate that in prostate cancer, PSMA initiates signaling upstream of PI3K through G protein-coupled receptors, specifically via the metabotropic glutamate receptor (mGluR). PSMA's carboxypeptidase activity releases glutamate from vitamin B9 and other glutamated substrates, which activate mGluR I. Activated mGluR I subsequently induces activation of phosphoinositide 3-kinase (PI3K) through phosphorylation of p110ß independent of PTEN loss. The p110ß isoform of PI3K plays a particularly important role in the pathogenesis of prostate cancer, but the origin of its activation was so far unknown. PSMA expression correlated with PI3K-Akt signaling in cells, animal models, and patients. We interrogated the activity of the PSMA-PI3K axis through positron emission tomography and magnetic resonance imaging. Inhibition of PSMA in preclinical models inhibited PI3K signaling and promoted tumor regression. Our data present a novel oncogenic signaling role of PSMA that can be exploited for therapy and interrogated with imaging.

Endoscopic ultrasound-guided tissue sampling of small subepithelial tumors of the upper gastrointestinal tract with a 22-gauge core biopsy needle.

Background and study aims The optimal approach to small subepithelial tumors (SETs) of the upper gastrointestinal tract remains inconclusive. The aim of this study was to evaluate endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) for less invasive tissue sampling of small SETs of the upper gastrointestinal tract. Patients and methods In this prospective observational study patients with small ( ≤ 3 cm) SETs of the upper gastrointestinal tract were eligible and underwent EUS-FNB with a 22-gauge core biopsy needle. The main outcome measure was the diagnostic yield. The number of obtained core biopsies was also assessed. Results Twenty patients were included. The mean SET size was 16 mm (range 10 - 27 mm). EUS-FNB was technically feasible in all cases and no complications were observed. The diagnostic yield was 75 %. Core biopsy specimens were obtained in only 25 % of cases. Conclusion EUS-FNB with a 22-gauge core biopsy needle of small SETs can achieve a definite diagnosis in the majority of cases. However, because core samples cannot regularly be obtained, EUS-FNB seems not to be convincingly superior to standard EUS-FNA in this setting.

Multiparametric 18F-FDG PET/MR follow-up in a patient with autoimmune pancreatitis.

BACKGROUND: Positron emission tomography/magnetic resonance imaging (PET/MR) is a new multimodal imaging technique, which might improve the diagnostic performance not only in oncological patients but also in patients with non-neoplastic inflammatory lesions as routinely used 18F-FDG is not a cancer specific agent. CASE PRESENTATION: Multiparametric 18F-FDG PET/MR in a woman with pain in the upper abdomen and inconclusive laboratory and clinical data presenting with moderately increased, diffuse 18F-FDG uptake with delayed contrast enhancement, diffusion-restriction and focal enlargement in the pancreatic body being suggestive for autoimmune pancreatitis (AIP). Follow-up 18F-FDG PET/MR after initiation of steroid therapy confirmed complete resolution of imaging abnormalities. CONCLUSION: 18F-FDG PET/MR might be valuable in the management of AIP providing complementary data regarding accurate diagnosis and monitoring therapy response to avoid unnecessary surgery.

High-mass-resolution MALDI mass spectrometry imaging of metabolites from formalin-fixed paraffin-embedded tissue.

Formalin-fixed and paraffin-embedded (FFPE) tissue specimens are the gold standard for histological examination, and they provide valuable molecular information in tissue-based research. Metabolite assessment from archived tissue samples has not been extensively conducted because of a lack of appropriate protocols and concerns about changes in metabolite content or chemical state due to tissue processing. We present a protocol for the in situ analysis of metabolite content from FFPE samples using a high-mass-resolution matrix-assisted laser desorption/ionization fourier-transform ion cyclotron resonance mass spectrometry imaging (MALDI-FT-ICR-MSI) platform. The method involves FFPE tissue sections that undergo deparaffinization and matrix coating by 9-aminoacridine before MALDI-MSI. Using this platform, we previously detected ∼1,500 m/z species in the mass range m/z 50-1,000 in FFPE samples; the overlap compared with fresh frozen samples is 72% of m/z species, indicating that metabolites are largely conserved in FFPE tissue samples. This protocol can be reproducibly performed on FFPE tissues, including small samples such as tissue microarrays and biopsies. The procedure can be completed in a day, depending on the size of the sample measured and raster size used. Advantages of this approach include easy sample handling, reproducibility, high throughput and the ability to demonstrate molecular spatial distributions in situ. The data acquired with this protocol can be used in research and clinical practice.

Value of 68Ga-PSMA HBED-CC PET for the Assessment of Lymph Node Metastases in Prostate Cancer Patients with Biochemical Recurrence: Comparison with Histopathology After Salvage Lymphadenectomy.

The purpose of this study was to evaluate the accuracy of Glu-NH-CO-NH-Lys-(Ahx)-[68Ga(HBED-CC)] PET compared with morphologic imaging for the assessment of lymph node metastases (LNM) in patients with recurrent prostate cancer. METHODS: Forty-eight patients (median age, 71 y; interquartile range, 66-74 y) with biochemical recurrence (median prostate-specific antigen level, 1.31 ng/mL; interquartile range, 0.75-2.55 ng/mL) who underwent 68Ga-prostate-specific membrane antigen (PSMA) HBED-CC PET/CT or PET/MR and salvage lymphadenectomy were retrospectively included. Institutional review board approval and written informed consent were obtained from all patients for the purpose of anonymized evaluation and publication of their data. Standardized predefined lymph node (LN) template fields (n = 10) were evaluated in 68Ga-PSMA HBED-CC PET and morphologic imaging for the presence of LNM using a 5-point-scale. Additionally, SUVmean/max and size of suspicious lesions were determined. Specificity of 68Ga-PSMA HBED-CC PET imaging for PET-positive LNs was defined by comparison to histopathology. The diagnostic accuracy of 68Ga-PSMA HBED-CC PET compared with morphologic imaging alone was assessed, and areas under the receiver-operating-characteristic curves are presented. RESULTS: LNM were found histologically in 68 of 179 resected anatomic LN fields (38.0%). The specificity of 68Ga-PSMA HBED-CC PET and morphologic imaging was 97.3% and 99.1%, respectively. However, 68Ga-PSMA HBED-CC PET detected LNM in 53 of 68 histopathologically proven metastatic LN fields (77.9%) whereas morphologic imaging was positive in only 18 of 67 (26.9%). 68Ga-PSMA HBED-CC PET imaging performed significantly superior to morphologic imaging for detection of LNM (difference in the areas under the receiver-operating-characteristic curves, 0.139; 95% confidence interval, 0.063-0.214; P < 0.001). In 68Ga-PSMA HBED-CC PET, the mean size of PET-positive LN measured by CT or MRI was 8.3 ± 4.3 mm (range, 4-25 mm), and LNs, which were suspicious only in CT or MRI, presented with a mean size of 13.0 ± 4.9 mm (range, 8-25 mm). CONCLUSION: 68Ga-PSMA HBED-CC PET imaging is a promising method for early detection of LNM in patients with biochemical recurrent prostate cancer. It is more accurate than morphologic imaging and thus might represent a valuable tool for guiding salvage lymphadenectomy.