This study is designed to obtain an imaging training set that will be used to evaluate images in future trials. Currently, no radiopharmaceutical diagnostic imaging agent has been approved by the FDA in the U.S. for use in diagnosing Parkinson disease and related Parkinsonian syndromes. The diagnosis of Parkinsonian syndromes in the U.S. is based on clinical criteria only. The goal is to demonstrate that 123I-ALTROPANE® paired with SPECT imaging permits a more accurate early diagnosis of Parkinson disease than a clinical diagnosis by a general neurologist.

This is a prospective, multi-center, non-randomized, open-label, out patient clinical trial which will include up to 90 subjects, male or female, 40 years of age or older.

This study is designed to obtain an imaging training set that will be used to evaluate images in future trials. Up to ninety subjects with upper extremity tremor for less than 2 years duration will be enrolled. Of these, at least thirty Parkinsonian syndromes subjects and at least thirty non-Parkinsonian syndromes subjects as diagnosed by a MDS will be enrolled.

Subjects will participate in three study visits over the course of the study period. The screening visit will include an assessment of eligibility as well as the collection of the MDS diagnosis. The second visit, during which all subjects receive a single intravenous injection of 123I-ALTROPANE® followed by SPECT imaging, will include appropriate safety assessments before and after dosing. The third visit will include follow-up safety. The subjects' participation in the study will range between 30 and 40 days.

• Subjects with Parkinsonian Tremor (PT)
• Subjects with non Parkinsonian Tremor (nPT)

Inclusion Criteria:

1. Subjects must provide written informed consent prior to the initiation of any study related procedures;
2. Subjects ≥ 40 years of age;
3. Subjects with upper extremity tremor for < 2 years duration.

Exclusion Criteria:

1. Any clinically significant acute or unstable physical or psychological illness based on medical history or physical examination at Visit 1, as determined by the Principal Investigator;
2. Any unexpected clinically significant abnormal laboratory or ECG results obtained at Visit 1 and as determined by the Principal Investigator;
3. Any history of drug, narcotic, or alcohol abuse within 2 years prior to the date of informed consent, as defined by the Diagnostic and Statistical Manual of the American Psychiatric Association, 4th Edition (DSM-IVR {American Psychiatric Association, 1994 #2});
4. Positive urine drug screen at Visit 1;
5. Participation in an investigational drug or device clinical trial within 30 days prior to the date of informed consent;
6. Previous participation in any 123I-ALTROPANE® trial;
7. Any exposure to radiopharmaceuticals within 30 days prior to the date of informed consent;
8. Positive (+) pregnancy test at Visit 1 and/or Visit 2;
9. Breast-feeding;
10. Inability to lie supine for 1 hour;
11. Any significant active thyroid disease;
12. Known sensitivity or allergy to Iodine or Iodine containing products;
13. A history of repeated head injury or sustained severe head injury in year prior to onset of tremor;
14. A definitive diagnosis of encephalitis;
15. Any uncontrolled hypertension or diabetes;
16. Any history of cerebrovascular disease;
17. Previous evaluation by a Movement Disorder Specialist (MDS);
18. Treatment within the previous six (6) months prior to informed consent with bupropion, metoclopramide, cinnarizine, flunarizine, methylphenidate, reserpine, modafinil, alpha methyldopa, amphetamine, or any anti-psychotic medication;
19. Any treatment with anti-Parkinson's drugs or anti-tremor medications within three (3) months prior to the date of the subject signing the informed consent;
20. Any new prescription or change in dose of medications for chronic conditions within four (4) weeks of Visit 2.