MRI — Principles and Safety

A 52-year-old man with a history of occupational exposure to metal shavings presents to the radiology department for MRI of the lumbar spine to evaluate chronic lower back pain. During the pre-scan safety interview, he reports that a metal fragment may have entered his left eye 15 years ago during a grinding accident, though he never sought medical attention. On examination, visual acuity is normal and anterior segment appears intact. What is the most appropriate next step before proceeding with MRI?

A 52-year-old man with a history of myocardial infarction 8 years ago presents to the radiology department for MRI of the lumbar spine to evaluate chronic back pain. During the pre-scan safety interview, he reports that he underwent coronary stent placement following his MI. He cannot recall the exact type of stent or the date of implantation. His current medications include aspirin and atorvastatin. What is the most appropriate next step?

A 34-year-old woman with a 6-month history of severe headaches is referred for brain MRI. During the pre-scan interview, she discloses that she has a permanent pacemaker implanted 3 years ago for complete heart block. The pacemaker was implanted at a tertiary care center, and she has regular follow-up appointments. She is currently asymptomatic and on no medications. The radiology technician informs her that MRI is contraindicated and suggests CT instead. The patient is frustrated because her cardiologist mentioned that her pacemaker "might be MRI-conditional." What is the most appropriate management?

A 34-year-old woman with a history of renal failure secondary to lupus nephritis is referred for MRI of the abdomen to evaluate for retroperitoneal fibrosis. She had received gadolinium-based contrast (GBCA) for a prior MRI 3 months ago. Her current eGFR is 28 mL/min/1.73m². On review of her previous imaging report, the contrast used was gadodiamide (linear GBCA). She is asymptomatic with no skin changes. What is the most appropriate management regarding gadolinium exposure and future imaging?

Which of the following statements best describes the physical basis of T1 relaxation in MRI?