Carbon-11-Labeled Methionine PET/CT in Patients With FDG-Occult Multiple Myeloma: A Prospective Pilot Study.

In a pilot study (ClinicalTrials.gov NCT02646085), seven patients with treated multiple myeloma and negative FDG PET/CT underwent amino acid imaging with 11C-methionine PET/CT. In five participants, 11C-methionine PET/CT showed focal uptake corresponding with lytic lesions; two to 18 lesions were found (SUVmax, 2.8-6.4). Findings indicated a potential role for 11C-methionine PET/CT in detecting residual disease after negative FDG PET/CT, thereby guiding further treatment.

Utility of 18F-Fluciclovine PET/CT for Detecting Prostate Cancer Recurrence in Patients With Low (< 1 ng/mL) or Very Low (< 0.3 ng/mL) Prostate-Specific Antigen Levels.

OBJECTIVE. We reviewed a retrospective series of 126 18F-fluciclovine PET/CT studies of patients with biochemically recurrent prostate cancer at low (< 1 ng/mL) and very low (< 0.3 ng/mL) prostate-specific antigen (PSA) levels. CONCLUSION. The rate of PET/CT positivity was 33% (15/46) in patients with low PSA levels and 0% (0/17) in patients with very low PSA levels. Our results suggest that 18F-fluciclovine PET/CT can be helpful for localizing recurrence in patients with PSA levels between 0.3 and 1 ng/mL and that 18F-fluciclovine PET/CT is not recommended in patients with PSA levels less than 0.3 ng/mL.

Safety of Administering Furosemide During Nuclear Diuretic Renography in Patients With Sulfonamide Allergies.

OBJECTIVE: We reviewed the safety of nuclear diuretic renography with furosemide in patients with sulfonamide allergies. The electronic health record was used to uncover any drug effects reported within 30 days of diuretic renograms performed between January 2009 and December 2015. CONCLUSION: Eighty-three of 1103 (7.5%) diuretic renograms were performed on patients with sulfonamide allergies. Two instances of minor rash occurred. No serious reactions occurred. Furosemide is associated with an extremely low risk of minor reactions in patients with sulfonamide allergies.

Fluorodeoxyglucose positron emission tomography for detection of tumor recurrence following radiofrequency ablation in retrospective cohort of stage I lung cancer.

PURPOSE: The goal of this study was to define patterns for tumor recurrence on PET following RFA, compare time to imaging recurrence by PET versus CT, evaluate whether pre-treatment tumor uptake predicts recurrence and propose an optimal post-RFA surveillance strategy. MATERIALS AND METHODS: A retrospective cohort study was performed of biopsy confirmed primary stage I lung cancers treated with RFA. FDG PET and near contemporaneous diagnostic CT imaging pre-ablation, within 30 days post-ablation, and beyond 6 months were independently and retrospectively evaluated for features supportive of recurrence. Time to imaging recurrence by PET (TTR_PET) and by CT (TTR_CT) were determined and compared. FDG avidity of untreated tumors was compared between recurrent and non-recurrent groups. RESULTS: Thirteen recurrences after 72 RFA treatments were confirmed by diagnostic CT. All recurrences were associated with focally intense and increasing FDG uptake beyond 6 months (sensitivity 100%; specificity 98.5%). Mean TTR_PET was 14 months compared to mean TTR_CT of 17 months (not statistically significant). Normalized SUVmax and total lesions glycolysis of lung cancers that recurred after RFA was 4.0 and 6.0, respectively compared to 2.8 and 5.0, respectively for cancers that did not recur (p = .068). CONCLUSION: A pattern of focally intense and increasing FDG PET uptake has high sensitivity and specificity for detecting recurrent lung cancer following RFA. Surveillance after RFA should include a contrast enhanced diagnostic CT at 1 month to diagnose procedural complications, PET at 6 months as a post-treatment metabolic baseline (with diagnostic CT if PET is abnormal) and alternating diagnostic CTs or PET every 6 months for 2 years.

Clinical evaluation of a mobile digital specimen radiography system for intraoperative specimen verification.

OBJECTIVE: Use of mobile digital specimen radiography systems expedites intraoperative verification of excised breast specimens. The purpose of this study was to evaluate the performance of a such a system for verifying targets. MATERIALS AND METHODS: A retrospective review included 100 consecutive pairs of breast specimen radiographs. Specimens were imaged in the operating room with a mobile digital specimen radiography system and then with a conventional digital mammography system in the radiology department. Two expert reviewers independently scored each image for image quality on a 3-point scale and confidence in target visualization on a 5-point scale. A target was considered confidently verified only if both reviewers declared the target to be confidently detected. RESULTS: The 100 specimens contained a total of 174 targets, including 85 clips (49%), 53 calcifications (30%), 35 masses (20%), and one architectural distortion (1%). Although a significantly higher percentage of mobile digital specimen radiographs were considered poor quality by at least one reviewer (25%) compared with conventional digital mammograms (1%), 169 targets (97%), were confidently verified with mobile specimen radiography; 172 targets (98%) were verified with conventional digital mammography. Three faint masses were not confidently verified with mobile specimen radiography, and conventional digital mammography was needed for confirmation. One faint mass and one architectural distortion were not confidently verified with either method. CONCLUSION: Mobile digital specimen radiography allows high diagnostic confidence for verification of target excision in breast specimens across target types, despite lower image quality. Substituting this modality for conventional digital mammography can eliminate delays associated with specimen transport, potentially decreasing surgical duration and increasing operating room throughput.

Comparison of 18F-DCFPyL and 68Ga-PSMA-11 for 177Lu-PSMA-617 therapy patient selection.

Purpose: 68Ga-PSMA-11 is recommended for the selection of patients for treatment in the package insert for 177Lu-PSMA-617. We aimed to compare imaging properties and post-treatment outcomes from radioligand therapy (RLT) of patients selected with 68Ga-PSMA-11 and 18F-DCFPyL. Methods: We retrospectively evaluated 80 patients undergoing PSMA RLT, who had pretreatment imaging using either 68Ga-PSMA-11 or 18F-DCFPyL. For both groups, we compared the biodistribution and lesion uptake and the PSA response to treatment. Results: Both agents had comparable biodistribution. Patients initially imaged with 18F-DCFPyL had a higher PSA response (66% vs. 42%), and more patients had a PSA50 response (72% vs. 43%) compared to patients imaged with 68Ga-PSMA-11. Conclusion: 18F-DCFPyL and 68Ga-PSMA-11 had comparable biodistribution and lesion uptake. Patients imaged with 18F-DCFPyL demonstrated clinical benefit to PSMA RLT comparable to those imaged with 68Ga-PSMA-11, and either agent can be used for screening patients.

Real-World Experience with 177Lu-PSMA-617 Radioligand Therapy After Food and Drug Administration Approval.

We report our initial real-world experience with 177Lu-PSMA-617 radioligand therapy. Methods: We performed a retrospective review of patients treated with 177Lu-PSMA-617. Pretreatment PSMA PET, laboratory findings, overall survival, a fall in prostate-specific antigen by 50% (PSA50), and toxicities were evaluated. Results: Ninety-nine patients were included. Sixty patients achieved a PSA50. Seven of 18 (39%) patients who did not meet the TheraP PSMA imaging criteria achieved a PSA50. Nineteen of 31 (61%) patients who did not meet the VISION laboratory criteria achieved a PSA50. Sixty-three patients had a delay or stoppage in therapy, which was due to a good response in 19 patients and progressive disease in 14 patients. Of 10 patients with a good response who restarted treatment, 9 subsequently achieved a PSA50 on retreatment. The most common toxicities were anemia (33%) and thrombocytopenia (21%). Conclusion: At our center, patients who did not meet the TheraP PSMA imaging criteria or the VISION laboratory criteria benefited from 177Lu-PSMA-617 radioligand therapy.

Tissue-based T cell activation and viral RNA persist for up to 2 years after SARS-CoV-2 infection.

The mechanisms of postacute medical conditions and unexplained symptoms after SARS-CoV-2 infection [Long Covid (LC)] are incompletely understood. There is growing evidence that viral persistence, immune dysregulation, and T cell dysfunction may play major roles. We performed whole-body positron emission tomography imaging in a well-characterized cohort of 24 participants at time points ranging from 27 to 910 days after acute SARS-CoV-2 infection using the radiopharmaceutical agent [18F]F-AraG, a selective tracer that allows for anatomical quantitation of activated T lymphocytes. Tracer uptake in the postacute COVID-19 group, which included those with and without continuing symptoms, was higher compared with prepandemic controls in many regions, including the brain stem, spinal cord, bone marrow, nasopharyngeal and hilar lymphoid tissue, cardiopulmonary tissues, and gut wall. T cell activation in the spinal cord and gut wall was associated with the presence of LC symptoms. In addition, tracer uptake in lung tissue was higher in those with persistent pulmonary symptoms specifically. Increased T cell activation in these tissues was also observed in many individuals without LC. Given the high [18F]F-AraG uptake detected in the gut, we obtained colorectal tissue for in situ hybridization of SARS-CoV-2 RNA and immunohistochemical studies in a subset of five participants with LC symptoms. We identified intracellular SARS-CoV-2 single-stranded spike protein-encoding RNA in rectosigmoid lamina propria tissue in all five participants and double-stranded spike protein-encoding RNA in three participants up to 676 days after initial COVID-19, suggesting that tissue viral persistence could be associated with long-term immunologic perturbations.

Key Factors to Attract More U.S. Diagnostic Radiology Residents into the Field of Nuclear Medicine and Molecular Imaging: A National Survey.

RATIONALE AND OBJECTIVES: To understand the current state of radiology residents' exposure to nuclear medicine and molecular imaging (NM/MI), determine key factors that may attract more trainees into the field, and identify differentiating aspects between those specializing in NM/MI and those who are not. MATERIALS AND METHODS: An anonymous web-based survey was sent to contacts at all diagnostic radiology residency programs in the United States for dissemination to their residents, collecting information about trainees' NM/MI exposure during residency and factors that may attract them to NM/MI. RESULTS: A total of 198 trainees responded to the survey, 34 of whom plan on pursuing a career in NM/MI. Most trainees reported early exposure to NM/MI during residency; most (97.4%) reported ample exposure to general NM/MI and oncologic studies. Less than 3% of trainees reported adequate exposure to therapies, neurological applications, molecular imaging/research advances, and physics. Respondents reported a need for better quality education (38.9%) and exposure to mentors (28.8%) as ways to attract trainees to NM/MI. Routinely encountered clinical pathology was the most interesting for those specializing in NM/MI (29.4%), whereas lifestyle was the most attractive aspect of NM/MI for those not pursuing a career in the field (27.4%). NM/MI-associated research was the least attractive for those specializing in NM/MI (35.3%), while job market concerns was the least attractive aspect for those not specializing in NM/MI (37.2%). Trainees planning to specialize in NM/MI reported higher satisfaction with their orientation to NM/MI during their first clinical rotation compared to those who do not plan to specialize in the field (3.03/5.00 and 2.67/5.00, respectively, p = 0.04). CONCLUSION: This survey highlights several factors that training programs and national societies can target to improve interest in NM/MI among radiology residents. We found that optimized education initiatives, including improved orientation to the field, increased mentoring, and career opportunities are essential levers for recruiting radiology trainees into the NM/MI workforce.

Multimodal Molecular Imaging Reveals Tissue-Based T Cell Activation and Viral RNA Persistence for Up to 2 Years Following COVID-19.

The etiologic mechanisms of post-acute medical morbidities and unexplained symptoms (Long COVID) following SARS-CoV-2 infection are incompletely understood. There is growing evidence that viral persistence and immune dysregulation may play a major role. We performed whole-body positron emission tomography (PET) imaging in a cohort of 24 participants at time points ranging from 27 to 910 days following acute SARS-CoV-2 infection using a novel radiopharmaceutical agent, [18F]F-AraG, a highly selective tracer that allows for anatomical quantitation of activated T lymphocytes. Tracer uptake in the post-acute COVID group, which included those with and without Long COVID symptoms, was significantly higher compared to pre-pandemic controls in many anatomical regions, including the brain stem, spinal cord, bone marrow, nasopharyngeal and hilar lymphoid tissue, cardiopulmonary tissues, and gut wall. Although T cell activation tended to be higher in participants imaged closer to the time of the acute illness, tracer uptake was increased in participants imaged up to 2.5 years following SARS-CoV-2 infection. We observed that T cell activation in spinal cord and gut wall was associated with the presence of Long COVID symptoms. In addition, tracer uptake in lung tissue was higher in those with persistent pulmonary symptoms. Notably, increased T cell activation in these tissues was also observed in many individuals without Long COVID. Given the high [18F]F-AraG uptake detected in the gut, we obtained colorectal tissue for in situ hybridization SARS-CoV-2 RNA and immunohistochemical studies in a subset of participants with Long COVID symptoms. We identified cellular SARS-CoV-2 RNA in rectosigmoid lamina propria tissue in all these participants, ranging from 158 to 676 days following initial COVID-19 illness, suggesting that tissue viral persistence could be associated with long-term immunological perturbations.

Incidence of nephrogenic systemic fibrosis after adoption of restrictive gadolinium-based contrast agent guidelines.

PURPOSE: To retrospectively determine the incidence of nephrogenic systemic fibrosis (NSF) in a large academic medical center after the adoption of restrictive gadolinium-based contrast agent (GBCA) administration guidelines. MATERIALS AND METHODS: For this retrospective HIPAA-compliant study, institutional review board approval was obtained and the requirement for informed consent was waived. Restrictive GBCA guidelines were adopted in May 2007. The guidelines (a) require a recent serum creatinine level measurement in any patient who is aged 60 years or older and/or at risk for renal disease, (b) limit the maximal weight-based GBCA dose administered to any patient with an estimated glomerular filtration rate (eGFR) lower than 60 mL/min/m(2) to 20 mL, and (c) prohibit the administration of any GBCA in patients who have an eGFR lower than 30 mL/min/m(2) and/or are undergoing chronic dialysis treatment (except in emergency situations). The electronic medical records were searched for all contrast material-enhanced magnetic resonance (MR) imaging examinations performed during the post-guidelines adoption period between January 2008 and March 2010 and the pre-guidelines adoption and transitional period between January 2002 and December 2007. Separate pathology records were searched for biopsy-confirmed cases of NSF during the same study periods. The incidences of NSF during the pre-guidelines adoption and transitional period and post-guidelines adoption period were compared by using the paired Z test. RESULTS: A total of 52,954 contrast-enhanced MR examinations were performed during the post-guidelines adoption period. Of these 52,954 examinations, 46,464 (88%) were performed in adult patients with an eGFR of 60 mL/min/m(2) or higher or presumed normal renal function and 6454 (12%) were performed in patients with an eGFR of 30-59 mL/min/m(2). Thirty-six patients with an eGFR lower than 30 mL/min/m(2) underwent contrast-enhanced MR imaging for emergent indications. Review of the pathology records for January 2008 to September 2010 revealed no new cases of NSF resulting from GBCA exposure. CONCLUSION: After restrictive guidelines regarding GBCA administration were instituted, no new cases of NSF were identified among 52,954 contrast-enhanced MR examinations, including those performed in patients with an eGFR lower than 60 mL/min/m(2).

Estrogen receptor-negative invasive breast cancer: imaging features of tumors with and without human epidermal growth factor receptor type 2 overexpression.

PURPOSE: To prospectively determine if estrogen receptor (ER)-negative human epidermal growth factor receptor type 2 (HER2)-positive and ER-negative HER2-negative breast cancers have distinguishing clinical and imaging features with use of retrospectively identified patients and tissue samples. MATERIALS AND METHODS: This HIPAA-compliant study was institutional review board approved. Informed consent was obtained from living patients and waived for deceased patients. Mean patient age at diagnosis was 53 years (range, 31-84 years). Clinical history; histopathologic, mammographic, and breast sonographic findings; and HER2 status as determined with immunohistochemistry or fluorescent in situ hybridization were evaluated in 56 women with ER-negative breast cancer. Imaging appearances and clinicopathologic characteristics were correlated with tumor HER2 status. P < .05 indicated a significant difference. RESULTS: Lesion margins on mammograms (P = .028) and sonograms (P = .023), calcifications on mammograms (P = .003), and clinical cancer stage at diagnosis (P = .029) were significantly associated with HER2 status. In contrast to ER-negative HER2-negative tumors, ER-negative HER2-positive tumors were more likely to have spiculated margins (56% vs 15%), be associated with calcifications (65% vs 21%), and be detected at a higher cancer stage (74% vs 57%). CONCLUSION: Biologic diversity of cancers may manifest in imaging characteristics, and, conversely, studying the range of imaging features of cancers may help refine current molecular phenotypes.

(18)F-FDG-PET/CT evaluation of response to treatment in lymphoma: when is the optimal time for the first re-evaluation scan?

Assessing the response to treatment as soon after treatment initiation is one of the key reasons for imaging lymphoma patients. The optimal time after initiating treatment for assessing response to treatment has yet to be determined. Therefore, we were prompted to review our experience with serial (18)F-FDG PET/CT in patients undergoing treatment for Hodgkin's disease (HD) and non Hodgkin's lymphoma (NHL). This is a retrospective study (Feb 2003 - Oct 2004) of 20 patients, 11 men and 9 women, with age range of 7-75 years with diagnosis of HD (10) and NHL (10), who had PET/CT at our institution prior, during and at the completion of therapy. Restaging PET/CT was done after 2 cycles of chemotherapy in 10 patients (group A) and after 4 cycles of chemotherapy in 10 pts (group B). A total of 60 scans were reviewed. The DeltaSUV from baseline to first PET/CT was on average 67.6% in group A and 75.1% in group B. This had no statistical significance (P value: 0.31). The DeltaSUV from baseline to post-therapy PET/CT was on average 72.9% in group A and 79.8% in group B. This difference also had no statistical significance (P value: 0.24). The correlation coefficient was 0.98 in group A and 0.80 in group B. Results of PET/CT after 2 cycles of chemotherapy did not statistically differ from the results of PET/CT after 4 cycles of chemotherapy. These results need to be confirmed in larger, prospective, randomized trials.

C11 Methionine PET (MET-PET) Imaging of Glioblastoma for Detecting Postoperative Residual Disease and Response to Chemoradiation Therapy.

PURPOSE: Response criteria of glioblastoma after chemoradiation do not account for metabolic changes that occur after treatment. The purpose of this study is to evaluate the utility of positron emission tomography (PET) imaging with C11 methionine (MET) (MET-PET) for detecting changes that occur after chemoradiation therapy and the value of molecular biomarkers for predicting the magnitude of metabolic response. METHODS AND MATERIALS: Patients with newly diagnosed glioblastoma undergoing standard chemoradiation treatment were enrolled in this prospective imaging study, with MET-PET scan performed within 3 days after surgical resection and again at 4 weeks after completion of chemoradiation. Near contemporaneous contrast-enhanced magnetic resonance imaging was performed within 2 weeks of each MET-PET scan. MET-PET imaging was analyzed for maximum standardized uptake value (SUV), SUVmean, and SUVvolume on a multimodality workstation. RESULTS: A total of 18 patients underwent baseline postoperative MET-PET imaging, 14 of whom underwent postchemoradiation MET-PET imaging. Among those who showed residual MET-avid disease on immediate postoperative MET-PET scans and underwent postchemoradiation MET-PET imaging (n = 10), mean ΔSUVmax was -40% (range -100% to 0%), mean ΔSUVmean was -35% (range -100% to 0%), and mean ΔSUV volume was -64% (range -100% to 0%). The Δtumor/brain reference was -40% (range -100% to 0%) using SUVmax and -35% (range -100% to 0%) using SUVmean. In contrast, none of the T2-weighted images on contrast-enhanced magnetic resonance imaging showed a >25% reduction in abnormal T2/fluid-attenuated inversion recovery signal on visual assessment. ΔSUVmax, ΔSUVmean, and ΔSUVvolume correlated with O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status (P = .01), but not with epidermal growth factor receptor or c-MET amplification status. All patients were IDH-1 wildtype. CONCLUSIONS: MET-PET scanning shows a significant decrease in metabolic signal at 1 month after chemoradiation compared with the immediate postoperative period, even when T2/fluid-attenuated inversion recovery changed little. MGMT promoter methylation status further predicts differential metabolic responses. MET-PET may be a useful tool for delineation of radiation targets and assessment of response.

Value of SPECT/CT for Sentinel Lymph Node Localization in the Parotid and External Jugular Chain.

OBJECTIVE: Preoperative single-photon emission computed tomography/computed tomography (SPECT/CT) imaging may aid in the localization of sentinel lymph nodes (SLNs) in cutaneous head and neck malignancy and has been rigorously evaluated for deep cervical lymph nodes. The purpose of this study was to assess the sensitivity, specificity, and positive predictive value (PPV) of SPECT/CT for preoperative localization of nodal basins superficial to the sternocleidomastoid muscle, with comparison to deep nodal basins of the neck. STUDY DESIGN: Retrospective review. SETTING: Tertiary care center. SUBJECTS AND METHODS: SPECT/CT images obtained preoperatively for patients undergoing SLN biopsy for cutaneous head and neck malignancy between June 2015 and June 2016 were reviewed by a blinded nuclear medicine physician and head and neck surgeon. SPECT/CT imaging was compared to intraoperatively determined SLN location via gamma probe. Sensitivity, specificity, and positive and negative predictive values were determined and compared for superficial (external jugular [EJ] and parotid) nodes vs level II nodes. RESULTS: Fifty-three patients were included in the study. Most had cutaneous melanoma (69.8%). The PPV of EJ/parotid node identification by SPECT/CT imaging was 85.7%, specificity was 88.9%, and sensitivity was 69.2%. Comparatively, the PPV for level II nodes was 76.9%, specificity was 50%, and sensitivity was 85.7%. No significant difference in SPECT/CT predictive value was identified between EJ/parotid and level II node identification ( P > .05). CONCLUSION: SPECT/CT imaging has strong specificity and positive predictability for preoperative localization of SLN superficial to the sternocleidomastoid muscle in cutaneous head and neck malignancy. SPECT/CT imaging may be a useful radiographic aid for preoperative SLN mapping in this patient population.