Got the Munchies for an Egg Sandwich? The Effects of Cannabis on Bowel Motility and Beyond.

The use of medicinal cannabis has a long history dating back thousands of years. Recent discoveries have shed light on its mechanism of action with the identification of cannabinoid receptors and endocannabinoids, which make up the body's endocannabinoid system. Cannabinoid receptors, particularly the cannabinoid 1 and 2 receptors, play a crucial role in modulating the gut-brain axis and serve as potential therapeutic targets for gastrointestinal motility and inflammatory disorders. With increasing legalization of cannabis and a rising number of users, understanding the effects of cannabis on gut motility is essential for nuclear medicine providers. Although tetrahydrocannabinol, the principal psychoactive constituent of cannabis, may decrease gut motility in experimental settings, it appears to paradoxically improve symptoms in gastroparesis. Treatment effects are difficult to measure given the large number of variables that could significantly alter outcomes, such as cannabinoid type, potency, and route of intake. Another consideration is the highly personalized gut microbiome, which directly interacts with the endocannabinoid system. Further research is required to delineate these multifaceted, complex cannabinoid interactions. The goal of this article is to explore the knowns and unknowns of the impact of cannabis on the alimentary system.

Universal Fasting Glucose Screening Before Gastric Emptying Scintigraphy and the High Prevalence of Undiagnosed Diabetes and Prediabetes.

The aim of this study was to assess the rates of undiagnosed diabetes mellitus (DM) and pre-DM in patients undergoing gastric emptying scintigraphy (GES). Diabetes is an epidemic in the United States, and the disease is associated with altered gut motility. As a result, we suspected that a significant number of patients referred for GES may have undiagnosed DM or pre-DM. Given that established procedure standards for GES require all patients to prepare with an 8-h fast, an opportunity is provided to measure the fasting blood glucose (FBG) in all individuals before they undergo the examination. Methods: The charts of patients undergoing GES were reviewed for a history of DM and correlated with FBG and GES results. FBG values, obtained by point-of-care testing, were categorized as normal, pre-DM, or DM. Results: Patients with known DM made up 23% of those referred for GES, and most (55%) had a normal FBG. In those without a history of DM, there were a significant number with undiagnosed pre-DM (12%) and DM (33%). Conclusion: Our study provides the first measure of the likely prevalence of undiagnosed DM and pre-DM and characterizes the different gastric emptying patterns among patients with normal FBG, likely undiagnosed pre-DM, likely undiagnosed DM, and known DM.

Practical Overview of 123I-Ioflupane Imaging in Parkinsonian Syndromes.

Parkinsonian syndromes are a heterogeneous group of progressive neurodegenerative disorders involving the nigrostriatal dopaminergic pathway and are characterized by a wide spectrum of motor and nonmotor symptoms. These syndromes are quite common and can profoundly impact the lives of patients and their families. In addition to classic Parkinson disease, parkinsonian syndromes include multiple additional disorders known collectively as Parkinson-plus syndromes or atypical parkinsonism. These are characterized by the classic parkinsonian motor symptoms with additional distinguishing clinical features. Dopamine transporter SPECT has been developed as a diagnostic tool to assess the levels of dopamine transporters in the striatum. This imaging assessment, which uses iodine 123 (123I) ioflupane, can be useful to differentiate parkinsonian syndromes caused by nigrostriatal degeneration from other clinical mimics such as essential tremor or psychogenic tremor. Dopamine transporter imaging plays a crucial role in diagnosing parkinsonian syndromes, particularly in patients who do not clearly fulfill the clinical criteria for diagnosis. Diagnostic clarification can allow early treatment in appropriate patients and avoid misdiagnosis. At present, only the qualitative interpretation of dopamine transporter SPECT is approved by the U.S. Food and Drug Administration, but quantitative interpretation is often used to supplement qualitative interpretation. The authors provide an overview of patient preparation, common imaging findings, and potential pitfalls that radiologists and nuclear medicine physicians should know when performing and interpreting dopamine transporter examinations. Alternatives to 123I-ioflupane imaging for the evaluation of nigrostriatal degeneration are also briefly discussed. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material. See the invited commentary by Intenzo and Colarossi in this issue.

Reexamining Compliance with Gastric Emptying Scintigraphy Guidelines: An Updated Analysis of the Intersocietal Accreditation Commission Database.

Many variables can influence the results of gastric emptying scintigraphy (GES). A lack of standardization causes variability, limits comparisons, and decreases the credibility of the study. To increase standardization, in 2009 the Society of Nuclear Medicine and Molecular Imaging (SNMMI) published a guideline for a standardized, validated GES protocol for adults based on a 2008 consensus document. Laboratories must closely follow the consensus guideline to provide valid and standardized results as an incentive to achieve consistency in patient care. As part of the accreditation process, the Intersocietal Accreditation Commission (IAC) evaluates compliance with such guidelines. The rate of compliance with the SNMMI guideline was assessed in 2016 and showed a substantial degree of noncompliance. The aim of this study was to reassess compliance with the standardized protocol across the same cohort of laboratories, looking for changes and trends. Methods: The IAC nuclear/PET database was used to extract GES protocols from all laboratories applying for accreditation from 2018 to 2021, 5 y after the initial assessment. The number of labs was 118 (vs. 127 in the initial assessment). Each protocol was again evaluated for compliance with the methods described in the SNMMI guideline. The same 14 variables were assessed in a binary fashion: patient preparation (4 variables-types of medications withheld, withholding of these medication for 48 h, blood glucose ≤ 200 mg/dL, blood glucose recorded), meal (5 variables-use of consensus meal, nothing by mouth for 4 h or more, meal consumed within 10 min, documentation of percentage of meal consumed, meal labeled with 18.5-37 MBq [0.5-1.0 mCi]), acquisition (2 variables-anterior and posterior projections obtained, imaging each hour out to 4 h), and processing (3 variables-use of the geometric mean, decay correction of data, and measurement of percentage retention). Results: Protocols from the 118 labs demonstrated that compliance is improving in some key areas but remains suboptimal in others. Overall, labs were compliant with an average of 8 of the 14 variables, with a low of 1-variable compliance at 1 site, and only 4 sites compliant with all 14 variables. Nineteen sites met an 80% threshold for compliance (11+ variables). The variable with the highest compliance was the patient's taking nothing by mouth for 4 h or more before the exam (97%). The variable with the lowest compliance was the recording of blood glucose values (3%). Notable areas of improvement include the use of the consensus meal, now 62% versus previously only 30% of labs. Greater compliance was also noted with measurement of retention percentages (instead of emptying percentages or half-times), with compliance by 65% of sites versus only 35% 5 y prior. Conclusion: Almost 13 y after the publication of the SNMMI GES guidelines, there is improving but still suboptimal protocol adherence among laboratories applying for IAC accreditation. Persistent variation in the performance of GES protocols may significantly affect patient management, as results may be unreliable. Using the standardized GES protocol permits interpretation of results in a consistent manner that allows interlaboratory comparisons and fosters acceptance of the test validity by referring clinicians.

Improving DXA Quality by Avoiding Common Technical and Diagnostic Pitfalls: Part 1.

Dual-energy x-ray absorptiometry (DXA) is an accurate means to assess bone mineral density, determine the risk of a fragility fracture, and monitor response to therapy. Despite its seemingly straightforward nature-the review of 2-to-3 nondiagnostic images and a few automatically generated numbers-the proper performance and interpretation of DXA can often be complex. It is complex because it is highly dependent on many factors, such as image acquisition, processing, analysis, and subsequent examination interpretation. Each step is subject to potential errors, artifacts, and diagnostic pitfalls; hence, meticulous attention must be paid to the technique by both the technologist and the interpreting physician to provide high-quality results and, in turn, maximize the examination's clinical utility. This article is part 1 of a 2-part series. Part 1 will begin with a review of bone physiology and osteoporosis etiology, followed by a discussion of the principles underlying DXA and the technical procedure. Part 2 will focus on DXA interpretation and discuss scanning pitfalls and clues to recognizing issues and improving scan quality.

ACR-ACNM-ASTRO-SNMMI Practice Parameter for Lutetium-177 (Lu-177) DOTATATE Therapy.

OBJECTIVES: This practice parameter (PP) for Lutetium-177 (Lu-177) DOTATATE peptide receptor radionuclide therapy (PRRT) aims to guide authorized users in selection of appropriate adult candidates with gastroeneropancreatic neuroendocrine tumors (GEP-NETs) from foregut, midgut, and hindgut. The essential selection criteria include somatostatin receptor-positive GEP-NETs, which are usually inoperable and progressed despite standard therapy. Lu-177 DOTATATE is a radiopharmaceutical with high avidity for somatostatin receptors that are overexpressed by these tumors. This document ensures safe handling of Lu-177 DOTATATE by the authorized users and safe management of affected patients. METHODS: The document was developed according to the systematic process developed by the American College of Radiology (ACR) and described on the ACR Web site (https://www.acr.org/Clinical-Resources/Practice-Parameters-and-Technical-Standards). The PP development was led by 2 ACR Committees on Practice Parameters (Nuclear Medicine and Molecular Imaging and Radiation Oncology) collaboratively with the American College of Nuclear Medicine, American Society of Radiation Oncology, and Society of Nuclear Medicine and Molecular Imaging. RESULTS: The Lu-177 DOTATATE PP reviewed pharmacology, indications, adverse effects, personnel qualifications, and required clinical evaluation before starting the treatment, as well as the recommended posttherapy monitoring, quality assurance, documentation, and appropriate radiation safety instructions provided in written form and explained to the patients. CONCLUSIONS: Lu-177 DOTATATE is available for therapy of inoperable and/or advanced GEP-NETs when conventional therapy had failed. It can reduce tumor size, improve symptoms, and increase the progression free survival. The PP document provides clinical guidance for authorized users to assure an appropriate, consistent, and safe practice of Lu-177 DOTATATE.

ACR-ACNM-ASTRO-SNMMI Practice Parameter for Lutetium-177 (Lu-177) DOTATATE Therapy.

OBJECTIVES: This practice parameter (PP) for Lutetium-177 (Lu-177) DOTATATE peptide receptor radionuclide therapy (PRRT) aims to guide authorized users in selection of appropriate adult candidates with gastroeneropancreatic neuroendocrine tumors (GEP-NETs) from foregut, midgut, and hindgut. The essential selection criteria include somatostatin receptor-positive GEP-NETs, which are usually inoperable and progressed despite standard therapy. Lu-177 DOTATATE is a radiopharmaceutical with high avidity for somatostatin receptors that are overexpressed by these tumors. This document ensures safe handling of Lu-177 DOTATATE by the authorized users and safe management of affected patients. METHODS: The document was developed according to the systematic process developed by the American College of Radiology (ACR) and described on the ACR Web site (https://www.acr.org/Clinical-Resources/Practice-Parameters-and-Technical-Standards). The PP development was led by 2 ACR Committees on Practice Parameters (Nuclear Medicine and Molecular Imaging and Radiation Oncology) collaboratively with the American College of Nuclear Medicine, American Society of Radiation Oncology, and Society of Nuclear Medicine and Molecular Imaging. RESULTS: The Lu-177 DOTATATE PP reviewed pharmacology, indications, adverse effects, personnel qualifications, and required clinical evaluation before starting the treatment, as well as the recommended posttherapy monitoring, quality assurance, documentation, and appropriate radiation safety instructions provided in written form and explained to the patients. CONCLUSIONS: Lu-177 DOTATATE is available for therapy of inoperable and/or advanced GEP-NETs when conventional therapy had failed. It can reduce tumor size, improve symptoms, and increase the progression free survival. The PP document provides clinical guidance for authorized users to assure an appropriate, consistent, and safe practice of Lu-177 DOTATATE.

Diuretic Renal Scintigraphy Protocol Considerations.

Diuretic renal scintigraphy plays a critical diagnostic role by providing a physiologic means for differentiating between obstructive and nonobstructive hydronephrosis as well as assessing the function of the affected kidney. The exam accuracy is highly dependent upon and benefits from close attention to the protocol. This article reviews kidney anatomy and physiology, patient preparation, available radiopharmaceuticals, diuretic administration, acquisition, processing, quantification, and interpretation criteria.

Diuretic Renal Scintigraphy: The State of Practice and a Potential Opportunity for Standardization.

OBJECTIVE: The aim of this study was to assess variation in diuretic renal scintigraphy (DRS) practice patterns and quantify compliance with the national guidance in a large cohort of laboratories from different institutions and practice settings across the United States. METHODS: By means of an institutional review board-approved protocol, we extracted 107 facility-specific, adult DRS protocols and associated 174 reports from the Intersocietal Accreditation Commission database, representing all laboratories applying for genitourinary scintigraphy certification during the 2016 to 2018 accreditation cycle. From these, we assessed 40 variables regarding facilities and staffing, patient preparation, examination technique and acquisition, image processing, and reporting. RESULTS: Review of protocols and reports demonstrates a very high degree of variability in DRS practice across the United States and suboptimal compliance with societal guidelines and practice parameters. Some of the more variable or underreported parameters include the use of patient hydration, type and dosage of radiopharmaceutical, dosage and timing of diuretic administration, quantitative parameters assessed, and report content. CONCLUSION: There is high variability in the performance and reporting of DRS among laboratories applying for accreditation, similar to that seen in studies of other nuclear medicine examinations. The wide degree of practice variance may have a significant impact on diagnostic accuracy and patient management, with inaccurate or incomplete results. This survey impresses the need for standardization and improved quality of this important nuclear medicine examination.

U.S. Diagnostic Reference Levels and Achievable Administered Activities for Adult Renal Scintigraphy: An Analysis of the Intersocietal Accreditation Committee Nuclear Laboratories.

The goal of this work was to determine U.S. diagnostic reference levels (DRLs) and achievable administered activities (AAAs) for adult renal scintigraphy. Methods: Under an Institutional Review Board-approved protocol, data were collected from the Intersocietal Accreditation Commission during one 3-y accreditation cycle encompassing 110 facilities. Elements included radiopharmaceutical, administered activity, practice type, and examination volume. DRLs and AAAs were calculated and compared with non-U.S. values and societal recommendations as available. Results: Ninety-three facilities provided data on 99mTc-mercaptoacetyltriglycine (99mTc-MAG3), and 15 provided data on 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) for adult renal scintigraphy exams. Analysis demonstrated a DRL of 392.2 MBq (10.6 mCi) for 99mTc-MAG3 and 531.7 MBq (14.4 mCi) for 99mTc-DTPA, with an AAA of 370 MBq (10 mCi) for 99mTc-MAG3 and 445.9 MBq (12.1 mCi) for 99mTc-DTPA. Conclusion: The resultant calculated novel U.S. DRLs and AAAs may serve as benchmarks that nuclear medicine facilities may use to refine renal scintigraphy protocols, reduce patient doses, and potentially guide future societal guideline recommendations.

Parotid Oncocytoma on 99mTc-Sestamibi Scintigraphy and SPECT/CT.

ABSTRACT: Oncocytomas in the parotid gland are a rare benign neoplasm composed of mitochondrial-rich oncocytes. Here we present the case of an 85-year-old man with a history of biopsy-proven right parotid gland oncocytoma who underwent 99mTc-sestamibi scintigraphy and SPECT/CT in the context of primary hyperparathyroidism. Focal intense uptake of radiotracer is detected within the right parotid gland on sestamibi scintigraphy. SPECT/CT confirms the localization of sestamibi uptake to the hyperattenuating parotid gland oncocytoma.

Using Abnormal Respiratory Motion on Myocardial Perfusion Scintigraphy as an Opportunity to Screen for Obstructive Sleep Apnea.

A pilot study was performed to determine whether the raw data from routinely obtained upright and supine myocardial perfusion scan (MPS) imaging could be used as an opportunity to screen for obstructive sleep apnea (OSA). We hypothesized that abnormal respiratory motion seen only on supine imaging (not upright imaging) corresponds with OSA. MPS supine-only respiratory motion was compared with known OSA diagnoses and with risk factors known to be associated with OSA. Methods: We reviewed 154 consecutive MPS studies from patients at our institution, including both exercise and chemical stress testing. All examinations were obtained because there was clinical suspicion of myocardial ischemia. We used the MPS panogram to assess for respiratory motion on supine stress or upright rest or stress imaging. We obtained the age, sex, body mass index, hypertensive history, and continuous positive airway pressure or OSA diagnosis history. Results: We compared the patients who had supine, stress-only respiratory motion with the remaining patients, assessing their OSA risk factors and known OSA diagnoses. In total, 65 patients (42.2%) had 3 or more OSA risk factors and 26 patients (16.9%) had a known OSA diagnosis. A similar percentage of patients with abnormal supine-only respiratory motion and patients with 3 or more OSA risk factors had a known OSA diagnosis, 9 (16.7%) and 14 (21.5%), respectively. Conclusion: We found a similar prevalence of known OSA diagnoses in patients with abnormal supine-only respiratory motion on MPS studies and patients with 3 or more OSA risk factors. The pilot study suggests that assessment of motion on MPS studies may provide an opportunity to also screen for OSA.

ACR-ACNM-ASTRO-SNMMI Practice Parameter for the Performance of Therapy With Radium-223.

AIM/OBJECTIVES/BACKGROUND: The goal of therapy with unsealed radiopharmaceutical sources is to provide either cure or significant prolongation of disease-specific survival, and effective reduction and/or prevention of adverse disease-related symptoms or untoward events while minimizing treatment-associated side effects and complications. Radium-223 dichloride (radium-223) is an alpha particle-emitting isotope used for targeted bone therapy. This practice parameter is intended to guide appropriately trained and licensed physicians performing therapy with radium-223. Such therapy requires close cooperation and communication between the physicians who are responsible for the clinical management of the patient and those who administer radiopharmaceutical therapy and manage the attendant side effects. Adherence to this parameter should help to maximize the efficacious use of radium-223, maintain safe conditions, and ensure compliance with applicable regulations. METHODS: This practice parameter was developed according to the process described on the American College of Radiology (ACR) website ("The Process for Developing ACR Practice Parameters and Technical Standards," www.acr.org/ClinicalResources/Practice-Parameters-and-Technical-Standards) by the Committee on Practice Parameters of the ACR Commission on Radiation Oncology in collaboration with the American College of Nuclear Medicine (ACNM), the American Society for Radiation Oncology (ASTRO), and the Society of Nuclear Medicine and Molecular Imaging (SNMMI). All these societies contributed to the development of the practice parameter and approved the final document. RESULTS: This practice parameter addresses the many factors which contribute to appropriate, safe, and effective clinical use of radium-223. Topics addressed include qualifications and responsibilities of personnel, specifications of patient examination and treatment; documentation, radiation safety, quality control/improvement, infection control, and patient education. CONCLUSIONS: This practice parameter is intended as a tool to guide clinical use of radium-223 with the goal of facilitating safe and effective medical care based on current knowledge, available resources and patient needs. The sole purpose of this document is to assist practitioners in achieving this objective.

It's About Quality, Not Quantity: Qualitative FDG PET/CT Criteria for Therapy Response Assessment in Clinical Practice.

OBJECTIVE. FDG PET/CT has emerged as an effective tool for the timely accurate assessment of how tumors respond to therapy. To standardize interpretation and reporting, numerous response criteria have been developed. This article will review the evolution of these criteria along with their strengths and weaknesses. CONCLUSION. Several qualitative assessments applicable to common malignancies have been developed in recent years that solve many of the challenges faced by their quantitative predecessors. These are reviewed, and information is provided regarding individual treatment efficacy and prognosis.

Utilizing the Cholecystagogue, Ensure Plus, Results in Similar Hepatobiliary Scintigraphy Study Results and Patient Outcomes Status Post Cholecystectomy, in Comparison With Sincalide.

OBJECTIVE: To determine if use of the oral cholecystagogue, Ensure Plus (EP), in hepatobiliary scintigraphy (HBS) leads to a similar distribution of normal and abnormal gallbladder ejection fractions (GBEFs) versus other historical secondary findings of chronic biliary disease in a similar patient population compared with the conventional cholecystokinin analog, sincalide. The HBS findings analyzed included the GBEF, small bowel transit time, gallbladder fill time, and reversal of the normal gallbladder versus small bowel transit. The secondary objectives were to determine whether patient outcomes were significantly different for EP and sincalide HBS study patients following cholecystectomy, namely, the surgical pathology and patient-reported biliary-type pain. METHODS: We reviewed all HBS examinations over a retrospective 34-month period. Data from 446 patients who underwent sincalide or EP HBS with GBEF determination for evaluation of chronic symptoms concerning for biliary etiology met the inclusion criteria. The aforementioned HBS findings and postsurgical patient outcomes were obtained for each patient group. RESULTS: Comparing HBS examinations performed with sincalide or EP, no significant differences were noted in the major HBS findings of similar patient populations. Outcomes for the sincalide and EP groups status post cholecystectomy were assessed to determine their sensitivity, specificity, positive predictive value, and negative predictive value. The outcomes assessed were the histopathology and patient-reported amelioration of biliary-type pain. No significant differences were noted. CONCLUSIONS: The sincalide and EP cholecystagogues did not lead to significantly different HBS findings for similar patient populations or postcholecystectomy outcomes.

Review of 18F-Fluciclovine PET for Detection of Recurrent Prostate Cancer.

Fluorine 18 (18F) fluciclovine (anti-1-amino-3-18F-fluorocyclobutane-1-carboxylic acid [FACBC]) is a radiolabeled amino acid analog that takes advantage of the amino acid transport upregulation in several types of cancer cells. FACBC is taken up to a greater extent in prostate cancer cells than in surrounding normal tissue, providing an opportunity for its use in cases of this common cancer. In 2016, the U.S. Food and Drug Administration found the accuracy of FACBC PET to be superior to that of other molecular imaging techniques and subsequently granted approval for its use in PET of recurrent prostate cancer. As FACBC is an 18F radiotracer, an on-site cyclotron is not required for its production. This feature enables the widespread clinical availability of this agent and, in turn, an opportunity for improved patient care. The clinical pharmacology and imaging features of FACBC are reviewed, and the role of this agent in the imaging of recurrent prostate cancer, within the context of research that supports its effectiveness, is discussed. The administration of and image acquisition facilitated by using FACBC, as compared with 18F fluorodeoxyglucose, which is more widely used, are described. In addition, the criteria for interpreting FACBC imaging findings are outlined, with emphasis on common causes of false-positive and false-negative findings. ©RSNA, 2019.

Optimizing the Diagnosis of Parkinsonian Syndromes With 123I-Ioflupane Brain SPECT.

OBJECTIVE. The purpose of this article is to provide a review of 123I-ioflupane SPECT in the evaluation of suspected parkinsonian syndromes (PSs). This collection of diseases presents frequent diagnostic challenges, even by movement disorder and dementia specialists. CONCLUSION. The 123I-ioflupane scan serves as an imaging biomarker of the status of presynaptic dopamine transporters (DATs) in the striatum. As a result of neuronal death, DATs are greatly reduced in patients with PS neurodegenerative disorders, whereas clinical mimics generally do not show striatal DAT loss. This provides a tremendous opportunity for 123I-ioflupane to aid in the accurate and timely diagnosis of these patients and optimize their management.

Split-Dose 18F-FDG PET/CT-Guided Microwave Ablation for Liver Metastasis Recurrence with Immediate Treatment Assessment.

A 48-y-old man with a history of colon cancer presented with recurrent hepatic metastasis along a prior microwave ablation bed. Split-bolus, intraprocedural 18F-FDG PET was performed to guide repeat microwave ablation and immediately confirm complete treatment. PET-guided ablation is highly accurate for targeting and treating malignant hepatic lesions and feasible for nonspecialized tertiary care hospitals without an onsite cyclotron.

ACR-ACNM Practice Parameter for the Performance of Fluorine-18 Fluciclovine-PET/CT for Recurrent Prostate Cancer.

The American College of Radiology (ACR) and American College of Nuclear Medicine (ACNM) collaborated to develop a clinical practice document for the performance of fluciclovine positron-emission tomography (PET) / computed tomography (CT) in the evaluation of patients with suspected prostate cancer recurrence based on the elevation of prostate-specific antigen (PSA) level (biochemical recurrence) after prior therapy. Prostate cancer is the third leading cause of cancer death in the United States. Up to 50% of patients diagnosed with prostate cancer will develop biochemical failure after initial therapy. The differentiation of local from extraprostatic recurrence plays a critical role in patient management. The use of functional imaging targeting features of cancer metabolism has proven highly useful in this regard. Amino acid transport is upregulated in prostate cancer. Fluciclovine (anti-1-amino-3-F-18-fluorocyclobutane-1-carboxylic acid, FACBC, Axumin™) is an artificial amino acid PET tracer which demonstrates utility in the diagnosis of recurrent prostate cancer with significant added value to conventional imaging.