A Microdose Trial Investigating Binding of [68Ga]Ga-DOTA-CYS-ATH001 in Healthy Subjects and Different Patient Groups.

Inclusion Criteria: 1. Willing and able to give written informed consent for participation in the trial and able to comply with all trial procedures and requirements. 2. Male or female participant aged 18 to 75 years, inclusive, at the screening visit. 3. Body mass index (BMI) ≥ 19 and \< 40.0 kg/m2 at the time of the screening visit. 4. Women of childbearing potential (WOCBP) must practice abstinence from heterosexual intercourse (only allowed when this is the preferred and usual lifestyle of the participant) or must agree to use a highly effective method of contraception with a failure rate of \< 1 % to prevent pregnancy from at least 2 weeks prior to administration of tracer for at least 1 week after the PET imaging examination (or for at least 1 weak after the last PET imaging examination for those participants undergoing test/retest PET imaging). In addition, any male partner of a female participant must, unless he has undergone vasectomy, agree to use a condom during the same time period. The following are considered highly effective methods of contraception: * combined (estrogen and progestogen-containing) hormonal contraception associated with inhibition of ovulation (oral, intravaginal, transdermal), * progestogen-only hormonal contraception associated with inhibition of ovulation (oral, injectable, implantable), * intra-uterine device \[IUD\]or intra-uterine hormone-releasing system \[IUS\]) WOCBP must refrain from donating eggs until 3 months after the last tracer administration. WOCBP with an exclusive male partner who has undergone vasectomy may choose not to use contraceptives. Women of non-childbearing potential are pre-menopausal females who have undergone any of the following surgical procedures; hysterectomy, bilateral salpingectomy, or bilateral oophorectomy, or who are post-menopausal defined as 12 months of amenorrhea (in questionable cases a blood sample with detection of follicle-stimulating hormone \[FSH\] \>25 IU/L is confirmatory). Male participants must be willing to use condom or be vasectomized or practice sexual abstinence from heterosexual intercourse (only allowed when this is the preferred and usual lifestyle of the participant) to prevent pregnancy and drug exposure of a partner and refrain from donating sperm from the administration of tracer until 3 months after the administration of tracer. Any female partner of a non-vasectomized male participant who is of childbearing potential must use contraceptive methods with a failure rate of \< 1% to prevent pregnancy (see above) from at least 2 weeks prior to administration of tracer to 4 weeks after administration of tracer. Cohort-specific inclusion criteria: Cohort 1 (healthy participants) 5. Medically healthy participant without abnormal clinically significant medical history, physical findings, vital signs, ECG, and laboratory values at the time of the screening visit, as judged by the Investigator. Cohort 2 (presumed MASH patients) MASH diagnosis based on non-invasive assessments. Participants should have a high level of disease activity with regards to pro-peptide of type III collagen (ProC3) as a marker of ongoing fibrogenesis. 6. Steatosis according to biopsy, radiology, or controlled attenuation parameter (CAP) (≥ 280 dB/M 8), assessments ≤ 24 weeks prior to the screening visit. 7. At least 1 cardiometabolic criteria from the following list: A. BMI ≥ 25 kg/m2 \[23 Asia\] OR waist circumference (WC) \> 94 cm (M) 80 cm (F) OR ethnicity adjusted, B. Fasting serum glucose ≥ 5.6 mmol/L \[100 mg/dL\] OR 2-hour post-load glucose levels ≥ 7.8 mmol/L \[≥ 140 mg/dL\] OR HbA1c ≥ 5.7% \[39 mmol/L) OR type 2 diabetes OR treatment for type 2 diabetes, C. Blood pressure ≥ 130/85 mmHg OR specific antihypertensive drug treatment, D. Plasma triglycerides ≥ 1.70 mmol/L \[150 mg/dL\] OR lipid-lowering treatment, E. Plasma high-density lipoprotein (HDL)-cholesterol ≤ 1.0 mmol/L \[40 mg/dL\] (M) and ≤ 1.3 mmol/L \[50 mg/dL\] (F) OR lipid-lowering treatment. 8. ProC3 ≥ 12.6 ng/mL. Cohort 3 (verified MASH patients) MASH diagnosis based on historical liver biopsy. Participants should have a high level of disease activity with regards to ProC3 as a marker of ongoing fibrogenesis, to allow for correlation to PET-tracer uptake. 9. Evidence of steatosis according to biopsy, radiology, or CAP (≥ 280 dB/M) or MRI-PDFF, assessments ≤ 24 weeks prior to the screening visit. 10. At least 1 cardiometabolic criteria from the following list: A. BMI ≥ 25 kg/m2 \[23 Asia\] OR WC \> 94 cm (M) 80 cm (F) OR ethnicity adjusted, B. Fasting serum glucose ≥ 5.6 mmol/L \[100 mg/dL\] OR 2-hour post-load glucose levels ≥ 7.8 mmol/L \[≥ 140 mg/dL\] OR HbA1c ≥ 5.7% \[39 mmol/L) OR type 2 diabetes OR treatment for type 2 diabetes, C. Blood pressure ≥ 130/85 mmHg OR specific antihypertensive drug treatment, D. Plasma triglycerides ≥ 1.70 mmol/L \[150 mg/dL\] lipid-lowering treatment, E. Plasma HDL-cholesterol ≤ 1.0 mmol/L \[40 mg/dL\] (M) and ≤ 1.3 mmol/L \[50 mg/dL\] (F) OR lipid-lowering treatment. 11. Historical liver biopsy 24 weeks to 4 weeks prior to inclusion with histologically proven metabolic dysfunction-associated steatotic liver disease (MASLD). 12. ProC3 ≥ 12.6 ng/mL. Cohort 4 (fibrostenotic CD patients) 13. Fibrostenotic CD as evidenced by persistent luminal narrowing with or without obstructive symptoms as assessed with MRI, ≤ 24 weeks prior to the screening visit OR fibrostenotic CD by positive colonoscopy up to 24 weeks prior to the screening visit. 14. Crohn's disease activity index (CDAI) \< 150 15. Calprotectin \< 250 16. C-reactive protein (CRP) \< 20 Cohort 5 (PSC patients) 17. Large duct PSC, including intrahepatic bile duct involvement, according to MRI/MRCP. 18. ProC3 ≥ 12.6 ng/mL Exclusion Criteria: 1. Any contraindication for MRI according to a standard checklist used in clinical practice, including claustrophobia, metallic implants or internal electrical devices (e.g., cochlear implant, nerve stimulator, gastric pacemaker, bladder stimulator, cardiac pacemaker, defibrillator, artificial valves in heart, aneurysm clips or coils, etc.), inability to stay in supine position for 90 minutes, and permanent makeup or tattoos which in the Investigator's opinion might jeopardize the participant's safety or interfere with the imaging assessments. 2. Having worked as a metal worker or welder. 3. History of any clinically significant disease or disorder which, in the opinion of the Investigator, may either put the participant at risk because of participation in the trial or influence the results or the participant's ability to participate in the trial. 4. Any clinically significant illness, medical/surgical procedure, or trauma within 4 weeks of the screening visit. 5. Any malignancy within the past 12 months before the screening visit, with the exception of successfully treated basal cell carcinoma of the skin or in situ prostate cancer under active surveillance, with no interventions scheduled during the period of trial participation. 6. Any planned major surgery within the duration of the trial participation. 7. Participants who are pregnant, currently breastfeeding, or intend to become pregnant during the course of the trial. 8. Any positive result at the screening visit for serum hepatitis B surface antigen, hepatitis B or C antibodies and/or human immunodeficiency virus (HIV). 9. Any chronic active infection (e.g., HIV, Hepatitis B or C, tuberculosis, etc.). 10. Poor peripheral venous access, as judged by the Investigator. 11. After 10 minutes of supine rest at the screening visit, any vital signs values outside the following ranges: * Systolic blood pressure: \< 90 or \>165 mmHg, or * Diastolic blood pressure \< 50 or \>100 mmHg, or * Pulse \< 40 or \> 90 bpm 12. The participant has a change in body weight ≥5%, 3 months before the screening visit. 13. The participant has any laboratory abnormality or condition that, in the Investigator's opinion, could adversely affect the safety of the participant or impair the assessment of trial results. 14. Clinically significantly abnormal 12-lead ECG recording result or cardiac symptoms as judged by the Investigator. 15. The participant is using any prohibited concomitant medications as described in the protocol, at the discretion of the Investigator. 16. Current use of any hormone therapy at doses that may cause metabolic interference as judged by the Investigator. Stable hormonal replacement therapy is allowed. 17. Currently participating, or previous participation in another clinical trial within 30 days prior to the screening visit or previous participation in another PET imaging trial within the last 12 months. 18. Positive screening result for alcohol at the screening visit (cohorts 1a and 1b only). 19. Ongoing or previous alcohol abuse, or long-standing excessive intake of alcohol, as judged by the Investigator. 20. Presence or history of drug abuse, as judged by the Investigator. 21. History of, or current use of anabolic steroids, as judged by the Investigator. 22. Plasma donation within 1 month of screening or blood donation (or corresponding blood loss) during the last 3 months prior to screening. 23. The Investigator considers the participant unlikely to comply with trial procedures, restrictions, and requirements. Additional exclusion criteria for all participants (cohorts 2-5): 24. The participant is receiving treatment with vitamin E, thiazolidinediones, or glucagon-like peptide-1 receptor agonists unless on a stable dose for 3 months before the screening Visit and is anticipated to maintain the same dosing regimen throughout trial participation. 25. Participants with HbA1c ≥48 mmol/mol (6.5%) at screening without a previous diagnosis of T2D must not take part in the study. Participants with a previous diagnosis of T2D are permitted to enter the study if on a stable regimen of antidiabetic therapy for at least 3 months before screening. Participants who are on a stable regimen of antidiabetic therapy for at least 3 months before screening and have HbA1c of ≥ 63 mmol/mol (9%) at screening should be excluded. 26. Clinically significant disease, apart from T2D, which in the opinion of the Investigator might interfere with the interpretation of the trial results and/or the safety of the participant, or in any other way unsuitable for participation in this clinical trial. 27. The participant has a severe immune-mediated inflammatory disease (IMID) (e.g., rheumatoid arthritis, spondylarthritis disease spectrum, connective tissue disorders, cutaneous inflammatory conditions such as psoriasis, atopic dermatitis, hidradenitis suppurativa, asthma, multiple sclerosis). Participants with inactive IMID or active IMID of mild to moderate severity are permitted to enter the trial. Additional exclusion criteria for MASH and PSC participants (cohorts 2-3, and 5) 28. Liver stiffness \> 25 kPa by transient elastography or any sign of decompensation. For cohorts 2 and 3, based on the FibroScan® evaluation on the screening visit, and for cohort 5 based on routine elastography performed ≤ 12 months. 29. For participants with biopsy-confirmed fibrosis stage F2 or F3, the participant has any of the following during the screening period: * Aspartate aminotransferase (AST) levels \> 5 x the upper limit of normal (ULN). * Alanine aminotransferase (ALT) levels \> 5 x ULN. * Alkaline phosphatase (ALP) ≥ 2 x ULN (cohorts 2 and 3) and ALP ≥ 10 (cohort 5). * Serum creatinine ≥1.5 x ULN or has an estimated glomerular filtration rate (eGFR) \< 45 mL/min/1.73m2 (the revised Lund-Malmö GFR estimating equation will be used). * International normalized ratio (INR) \&gt;1.3. * Total TBL ≥ULN (except for patients with a documented history of Gilbert's syndrome if direct bilirubin is within the normal reference range). * Direct bilirubin ≥ 3 x ULN. * Platelet count \< 60 x 109/L. * Presence or history of ascites, hepatic encephalopathy, or variceal bleeding. * Presence or history of Child-Pugh \> 6 (Class B or C), unless due to therapeutic anticoagulation. * Presence or history of Model for End-Stage Liver disease (MELD) score \>12 (only for cohorts 2-3). Note: It is the Investigator's decision, in consultation with the Sponsor, to allow participants to enter the study who have clinically meaningful rising tendencies in liver chemistries or significantly elevated liver chemistries that do not yet satisfy but could be interpreted as clinically concerning (i.e., AST or ALT \> 4 x ULN) at any visit during the screening period. 30. The participant has a change in body weight ≥ 5% after qualifying liver biopsy. Additional criteria for fibrostenotic CD participants (cohort 4) 31. MRI findings consistent with only inflammation, i.e., edema, hyperemic intestinal wall, restricted diffusion, mesenteric lymphadenopathy etc.