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.

Altered Biodistribution on 99m Tc-Dimercaptosuccinic Acid Renal Scan.

ABSTRACT: 99m Tc-dimercaptosuccinic acid ( 99m Tc-DMSA) scans are used to evaluate renal cortical defects typically related to parenchymal scarring or pyelonephritis, and ectopic renal parenchyma. 99m Tc-DMSA binds to metalloproteins in proximal tubular cells and typically localizes to the renal cortex, with minimal excretion. Planar and SPECT images are obtained 2 to 4 hours after IV administration of 99m Tc-DMSA. Altered 99m Tc-DMSA biodistribution has been reported in various conditions, including renal injury, technical issues, infiltrative processes, and hematologic disorders. Here, we present a case of altered biodistribution, with hepatic and splenic radiotracer uptake in the setting of hepatosplenomegaly and hematologic abnormalities concerning for a systemic hematologic disorder/lymphohistiocytosis.

Meckel diverticulum scintigraphy: technique, findings and diagnostic pitfalls.

Meckel diverticulum, the most common congenital anomaly of the gastrointestinal tract, results from the aberrant involution of the omphalomesenteric duct and accounts for more than 50% of unexplained lower gastrointestinal bleeding in the pediatric population. The most accurate imaging tool to identify a Meckel diverticulum containing ectopic gastric mucosa is the Technetium-99m pertechnetate Meckel scan, a scintigraphic study with a reported accuracy of 90% in the pediatric population. In addition to depicting a Meckel diverticulum with ectopic gastric mucosa, careful attention to the normal biodistribution of the radiotracer can lead to the identification of unexpected pathology with implications for patient management. This article serves to review the embryological origin and anatomical features of Meckel diverticulum, highlight the role of scintigraphy in evaluating Meckel diverticulum, and discuss the proper imaging technique when performing this test. We will focus on pitfalls that can lead to an erroneous diagnosis as well as incidental findings that can affect patient management.

Uptake Within Achilles Tendon on Posttherapy Radioiodine Whole-Body Scan Related to Gouty Tophus.

A 66-year-old man with history of papillary thyroid cancer status post total thyroidectomy underwent I-radioiodine ablation. Posttherapy I whole-body scan revealed unexpected activity within the left posterior ankle. SPECT/CT localized the radioiodine uptake to a gouty tophus in the Achilles tendon.

Noninfectious Cloudy Peritoneal Effluent in a Peritoneal Dialysis Patient with Mantle Cell Lymphoma.

A 77-year-old man on peritoneal dialysis (PD) presented repeatedly with cloudy spent dialysate containing an elevated mononuclear cell count. He had mantle cell lymphoma diagnosed by colonic polyp biopsy two years before the start of PD. The first episode of cloudy dialysate was treated for peritonitis. However, the culture of the peritoneal fluid was negative and the mononuclear cells were proven to be atypical lymphocytes of the mantle cell lymphoma variety. In addition to the peritoneal effluent, atypical lymphocytes were also found consistently in the patient's blood samples and once in his right pleural effusion. The patient exhibited high peritoneal transport status and clinical features of volume overload raising the question of alterations in the peritoneal transport processes in PD patients with malignancies involving the peritoneal membrane. Distinction between infectious and noninfectious cloudy dialysate and the potential of changes in the peritoneal membrane transport mechanisms are issues that should concern the care of PD patients with cloudy dialysate containing malignant cells.

Lessons learned from a study-group pilot program for medical students perceived to be 'at risk'.

BACKGROUND: At the University of New Mexico School of Medicine (UNM-SOM) we have noticed that some first year medical students have difficulty accurately assessing their academic skills and are often afraid to seek help. This leads to marginal performance and sometimes even failure. Therefore, we developed a preemptive intervention using peer-led study groups based on the personalized System of Instruction (PSI). AIM: The goal of this pilot study was to evaluate this approach for assisting students, interms of student success, and cast benefit. METHODS: Thirteen first-year medical students considered to be 'at risk' of academic difficulty took part in a six-month pilot intervention. They participated in structured study groups that were facilitated by upper-level medical students. The groups met twice weekly for up to two hours each time. The at-risk students took short multiple-choice quizzes and discussed major concepts. If students did not achieve 80% or better on the quizzes, they were required to take a second quiz to demonstrate mastery. Summative exam scores from four groups of students were compared: those with Medical College Admission Test (MCAT) scores <25, who received the study group intervention; their classmates with MCAT scores >25 who did not receive the intervention; and two matched groups from the previous year, none of whom had access to the structured study groups. RESULTS: No significant differences in exam scores were seen between the group who received the intervention and the matched group who did not. CONCLUSIONS: Despite this result, we learned several useful lessons about study groups and interactions between first-year and upper-level medical students: (1) Students perceived participation in the study groups as a good learning strategy, but preferred participation not be mandated. It may be preferable to train and encourage students to run their own study groups. (2) Both students and proctors acknowledged interpersonal benefits from the program but, as these benefits can be achieved by other means, an expensive proctor-based program is not, we believe, the best use of academic support resources. (3) Focus in the study groups was on content for the quizzes, but more attention to how-to-learn strategies may have had greater impact.