FINAL Term Question Answers for MRI (MS in Radiography & Imaging Technology)

Q1. What is the importance of Breast MRI?

Answer:

Breast MRI has become an important adjunctive tool in breast imaging and has multiple clinical indications.

Important points:

1. It is currently the most sensitive detection technique for breast cancer diagnosis.
2. It is useful for screening women at high risk of breast cancer.
3. It helps in diagnosis when mammography or ultrasound findings are suspicious or inconclusive.
4. It is useful for staging and preoperative assessment.
5. It can be used to assess response to neoadjuvant chemotherapy and residual disease.

Q2. Explain the principle of breast cancer detection by MRI.

Answer:

The basis of breast cancer detection by MRI is tumor neoangiogenesis.

1. Malignant tumors develop abnormal new blood vessels.
2. These vessels differ from vessels in normal tissue and benign lesions.
3. Tumor vessels have increased permeability or leakiness.
4. This causes early uptake of contrast material by the tumor.
5. Many cancers also show rapid contrast washout, producing a dynamic enhancement pattern useful in differentiating malignant from benign lesions.

Q3. What are the indications of Breast MRI?

Answer:

Screening

• Women at high risk of breast cancer.
• Obscured breast tissue, including silicone implants.

Diagnosis

• Suspicious mammographic lesion with negative ultrasound.
• Bloody nipple discharge.
• Indeterminate palpable finding with negative mammography and ultrasound.
• Occult breast primary with axillary metastases.

Staging

• Chest-wall invasion.
• Dense breasts.
• Implants.
• Infiltrating lobular cancer.
• DCIS without microcalcifications.

Treatment

• Assessment of response to neoadjuvant chemotherapy.
• Detection of residual disease.
• Differentiation of recurrence from postoperative scar.

Q4. What are the goals of breast cancer staging with MRI?

Answer:

The goals are:

1. Preoperative mapping before breast-conserving treatment to reduce positive margins.
2. Detection of multifocal cancer.
3. Detection of multicentric cancer.
4. Detection of occult contralateral breast cancer.
5. Detection of residual disease when the initial lumpectomy is incomplete.

Q5. Describe patient positioning and coils in Breast MRI.

Answer:

1. The patient is positioned prone.
2. Both breasts are placed into the cups of the breast coil.
3. Appropriate padding is used to minimize motion and transmitted vibration.
4. The breast is gently fixed in the section-encoding direction.
5. Patient comfort is important because the examination may last 30 minutes or longer and discomfort can produce motion.

Q6. What is the recommended MR field strength for Breast MRI?

Answer:

1. Breast MRI should be performed at 1.5 T or higher.
2. Higher field strength allows high-resolution imaging.
3. It provides adequate signal-to-noise ratio (SNR).
4. It permits the use of fat suppression.
5. At 3.0 T, there may be further improvement in SNR, image resolution and imaging speed.

Q7. Describe the basic Breast MRI imaging protocol.

Answer:

The protocol includes:

1. Bilateral morphological study.
2. High-spatial-resolution T2-weighted fast spin echo sequence.
3. T2 imaging is performed without fat saturation in the axial plane.
4. Bilateral 3D gradient-echo T1-weighted dynamic sequences are obtained.
5. Slice thickness is approximately 2–3 mm.

Q8. What is the contrast protocol in Breast MRI?

Answer:

1. Gadolinium chelates are administered intravenously.
2. Standard dose is 0.1 mmol/kg.
3. Injection rate is approximately 2 mL/s.
4. This is followed by saline flushing using an automatic injector.
5. Dynamic studies are post-processed using methods including temporal subtraction and dynamic analysis with representative curves.

Q9. Which normal breast structures may enhance on MRI?

Answer:

Normal enhancing structures include:

1. Blood vessels
2. Nipples
3. Intra-mammary lymph nodes
4. Normal fibroglandular tissue
5. Physiological enhancement related to the menstrual cycle.

These structures should not automatically be diagnosed as tumors.

Q10. Describe normal enhancement of fibroglandular breast tissue.

Answer:

Normal fibroglandular tissue, especially in premenopausal women:

1. Usually shows a low level of enhancement soon after contrast.
2. Enhancement is gradual.
3. It is progressive and faint over time.
4. It is generally bilateral and symmetrical.
5. Transient enhancing foci may occur, particularly during the second half of the menstrual cycle and around menstruation.

Q11. When should Breast MRI be performed in relation to the menstrual cycle?

Answer:

According to the slide:

• Breast imaging should preferably be performed during the second week of the menstrual cycle.
• This is because transient physiological enhancement may occur during the second half of the cycle.
• Such enhancement can mimic pathology.
• Performing MRI in the second week helps minimize false-positive diagnosis.
• Progesterone can also cause abnormal enhancement.

Q12. What is the effect of progesterone and hormone replacement therapy on Breast MRI?

Answer:

1. Progesterone can cause abnormal enhancement in approximately 50% of cases.
2. Hormonal effects may increase background breast enhancement.
3. Where possible, hormone replacement therapy should be discontinued 4–6 weeks before Breast MRI.
4. Anti-oestrogen medication may suppress physiological enhancement.
5. The slides do not recommend anti-oestrogen treatment solely to reduce physiological enhancement because of adverse effects.

BI-RADS MORPHOLOGY

Q13. What are the three main categories of enhancement in Breast MRI?

Answer:

According to the BI-RADS approach presented:

1. Mass
2. Non-mass-like enhancement
3. Focus

This distinction is important because each category has different diagnostic criteria and pathways.

Q14. Define a mass on Breast MRI.

Answer:

A mass is:

1. A three-dimensional lesion.
2. It occupies space.
3. It measures more than 5 mm.
4. It is usually visible on pre-contrast T1- or T2-weighted images.
5. It is described according to characteristics such as shape, margin and internal enhancement.

Q15. What are the BI-RADS descriptors for the shape of a breast mass?

Answer:

The shapes described in the slides are:

• Round — spherical.
• Oval — elliptical.
• Lobular — undulating contour.
• Irregular — uneven shape.

Round and oval shapes are presented as predictive of benignity.

Q16. What are the margin descriptors of a breast mass?

Answer:

The margin descriptors include:

1. Smooth
2. Irregular
3. Spiculated

A spiculated margin has sharp lines projecting from the mass.

A smooth margin is strongly associated with benignity in the slides.

Q17. What is the significance of smooth margins in a breast mass?

Answer:

1. Smooth margins are characterized by well-defined, sharply demarcated borders.
2. They have the highest benign lesion predictive value in the slide.
3. Approximately 97–100% of masses with smooth margins are reported as benign.
4. Margin analysis depends on spatial resolution.
5. Motion-related mis-registration can make margins appear poorly defined on subtraction images, so margin assessment should be made on appropriate anatomical/native images.

Q18. What are the internal enhancement patterns of a breast mass?

Answer:

The internal enhancement descriptors are:

1. Homogeneous enhancement
2. Heterogeneous enhancement
3. Rim enhancement
4. Internal non-enhancing septations
5. Enhancing septae / central enhancement as described in the BI-RADS table.

Q19. What is the significance of homogeneous enhancement?

Answer:

1. Homogeneous enhancement within a mass is highly suggestive of benignity in tumors larger than 1 cm.
2. However, the finding is less reliable in very small tumors.
3. Spatial resolution may limit evaluation.
4. Small breast cancers may also have homogeneous content.
5. Therefore morphology should be considered rather than relying on enhancement alone.

Q20. What is the significance of fat within a breast mass?

Answer:

Fat is assessed on unenhanced T1- or T2-weighted sequences without fat suppression.

Fat appears hyperintense.

Fat within a mass is associated with benign lesions such as:

• Hamartoma
• Fibroadenoma
• Intramammary lymph node
• Fat necrosis

Fat necrosis may appear irregular but fat-specific internal signal helps establish the diagnosis.

Q21. What are the important T2 signal characteristics of breast lesions?

Answer:

The slides emphasize:

• High signal on T2-weighted images may occur in benign lesions.
• Cysts are bright.
• Lymph nodes can be bright.
• Fat necrosis can show high signal.
• Colloid carcinoma is given as an important malignant exception that can also be bright on T2 fat-suppressed imaging.

Q22. What is rim enhancement and what is its significance?

Answer:

1. Rim enhancement means enhancement concentrated at the periphery of a mass.
2. It is generally regarded as suggestive of malignancy.
3. A regular enhanced rim can also occur around cysts.
4. It can occur around seromas.
5. It can occur around circumscribed fat necrosis, so mass content must be assessed to distinguish these benign entities from malignancy.

ENHANCEMENT KINETICS

Q23. What are enhancement kinetics in Breast MRI?

Answer:

Enhancement kinetics describe how a lesion takes up and loses contrast over time.

They are assessed in two phases:

1. Initial phase
2. Delayed phase

The initial phase occurs within the first 2 minutes and is categorized as slow, medium or fast.

Q24. Describe the three types of initial-phase enhancement.

Answer:

The initial phase is assessed within the first two minutes after contrast administration.

Q25. Describe the three types of delayed enhancement kinetics.

Answer:

The delayed phase consists of:

1. Persistent — enhancement continues to increase.
2. Plateau — there is no significant change after the initial phase.
3. Washout — signal intensity decreases.

The most suspicious kinetic feature should be reported when multiple kinetic patterns occur within a lesion.

Q26. Why is morphology more important than enhancement kinetics?

Answer:

1. A lesion can display several different kinetic patterns.
2. Malignant lesions may be more likely to show washout.
3. However, some studies have not found kinetics to be significant predictors of malignancy.
4. Therefore kinetics alone cannot reliably establish malignancy.
5. Morphology of the lesion should be the most important consideration.

CAD

Q27. What is Computer-Aided Detection (CAD) in Breast MRI?

Answer:

1. CAD provides a purely kinetic evaluation.
2. It does not evaluate the anatomy or pathology itself.
3. It analyzes contrast enhancement curves and peak enhancement.
4. It can perform multipanar reconstruction and subtraction rapidly.
5. In the slide’s color convention, red represents type 3 washout and is considered suspicious.

NON-MASS-LIKE ENHANCEMENT

Q28. Define non-mass-like enhancement.

Answer:

Non-mass-like enhancement is:

1. Enhancement of an area that is neither a mass nor a focus.
2. It has no space-occupying effect.
3. It is usually not seen as a lesion on unenhanced sequences.
4. Causes include mastopathic changes, fibrocystic changes and inflammatory changes.
5. It may also occur with DCIS, invasive lobular carcinoma and some estrogen-receptor-negative invasive ductal carcinomas.

Q29. Why is non-mass-like enhancement important?

Answer:

1. It does not form a discrete mass.
2. It may occur in otherwise normal-appearing fibroglandular tissue.
3. It can be caused by hormonal or fibrocystic changes.
4. It can also represent malignancy such as DCIS or invasive lobular carcinoma.
5. The slides identify non-mass-like enhancement as a major cause of false-positive breast findings.

Q30. What features suggest benign non-mass-like enhancement?

Answer:

Features include:

1. Bilateral symmetry.
2. Several microcysts or macrocysts on T2-weighted images.
3. Cysts distributed throughout the enhanced area.
4. Regional rather than ductal or segmental distribution.
5. A stippled pattern consisting of multiple enhancing dotted foci.

FOCUS

Q31. Define a focus in Breast MRI.

Answer:

A focus is:

1. A tiny enhancing dot.
2. It measures less than 5 mm.
3. It is not a space-occupying lesion.
4. It is too small for reliable morphological characterization.
5. It has no pre-contrast correlate.

Q32. What are common causes and characteristics of a focus?

Answer:

A focus is usually associated with benign lesions such as:

• Papilloma
• Fibroadenoma
• Intramammary lymph node
• Focal fibrocystic changes

It only rarely represents a small invasive cancer or DCIS.

Q33. How are foci assessed and categorized?

Answer:

1. Foci are usually too small for reliable morphological assessment.
2. A smooth outline should not be considered proof of benignity.
3. Quantitative kinetic curves are not possible.
4. Enhancement intensity and washout are assessed visually.
5. Numerous/bilateral foci may be BI-RADS 2, whereas an isolated focus without washout or BRCA mutation may be BI-RADS 3; isolated foci with washout or BRCA mutation are considered BI-RADS 4, for which biopsy is recommended.

Q34. What are benign and malignant features of a focus?

Answer:

Benign features

• Bright on T2-weighted imaging.
• Fatty hilum.
• Persistent kinetics.
• Stable since prior examination.

Malignant/suspicious features

• Not bright on T2.
• No fatty hilum.
• Washout kinetics.
• Larger or new focus compared with prior examination.

FINAL ASSESSMENT

Q35. What are the BI-RADS categories used for Breast MRI?

Answer:

• Category 0: Incomplete; additional imaging evaluation needed.
• Category 1: Negative.
• Category 2: Benign.
• Category 3: Probably benign.
• Category 4: Suspicious.
• Category 5: Highly suspicious of malignancy.
• Category 6: Known biopsy-proven malignancy.

Q36. What are the two main reasons for failure to detect enhancement in Breast MRI?

Answer:

The two main reasons are:

1. Small tumor size
2. Strong background enhancement in surrounding normal fibroglandular tissue.

The slides also emphasize paying attention to the first post-contrast acquisition when background enhancement is present.

Q37. What is mis-registration in Breast MRI?

Answer:

1. Mis-registration occurs because of motion between pulse-sequence images.
2. It can produce subtraction artifacts.
3. It can create pseudo-enhancement.
4. True enhancement may therefore be overlooked on subtraction images.
5. MR examinations should be interpreted using post-contrast native images and by comparing pre- and post-contrast native images.

15-MARK LONG QUESTIONS — BREAST MRI

LONG Q1. Describe Breast MRI indications, patient positioning, protocol and contrast administration.

Answer:

1. Indications

Breast MRI is used for:

Screening

• High-risk women.
• Obscured breast tissue/implants.

Diagnosis

• Suspicious mammographic lesion with negative ultrasound.
• Bloody nipple discharge.
• Indeterminate palpable lesion with negative mammography and ultrasound.
• Occult primary in patients with axillary metastases.

Staging

• Chest-wall invasion.
• Dense breasts.
• Implants.
• Infiltrating lobular carcinoma.
• DCIS without microcalcifications.

Treatment

• Assessment of neoadjuvant chemotherapy response.
• Detection of residual disease.
• Differentiation of recurrence from postoperative scar.

2. Patient positioning

• Patient is placed prone.
• Breasts are positioned within the coil cups.
• Padding minimizes motion and vibration.
• Breast immobilization is performed appropriately.
• Patient comfort is important because examination may last 30 minutes or longer.

3. Field strength

• Breast MRI should be performed at 1.5 T or higher.
• 3 T can provide increased SNR, resolution and faster imaging.

4. Imaging protocol

• Bilateral unenhanced high-resolution T2-weighted fast spin echo.
• Axial plane.
• Bilateral 3D T1-weighted dynamic gradient echo.
• With or without fat suppression.
• Slice thickness approximately 2–3 mm.

5. Contrast

• Intravenous gadolinium chelate.
• Dose: 0.1 mmol/kg.
• Injection rate: 2 mL/s.
• Followed by saline flush.
• Dynamic subtraction and kinetic analysis are performed.

This is a very strong 15-mark question.

LONG Q2. Describe the BI-RADS approach to characterization of breast lesions on MRI.

Answer:

When interpreting enhancement, the first step is to identify the type of lesion.

The three major categories are:

1. Mass

A mass is a three-dimensional, space-occupying lesion measuring >5 mm.

It is evaluated according to:

Shape

• Round
• Oval
• Lobular
• Irregular

Margin

• Smooth
• Irregular
• Spiculated

Internal enhancement

• Homogeneous
• Heterogeneous
• Rim enhancement
• Non-enhancing septations
• Enhancing septae/central enhancement.

2. Non-mass-like enhancement

It is enhancement that:

• Is neither a mass nor a focus.
• Has no space-occupying effect.
• Is not seen as a lesion on unenhanced sequences.

It may be associated with benign fibrocystic/hormonal changes or malignancy such as DCIS and invasive lobular carcinoma.

3. Focus

A focus is:

• <5 mm.
• Tiny enhancing dot.
• Not space occupying.
• Too small for morphological characterization.
• Has no pre-contrast correlate.

Thus, identification of mass, non-mass-like enhancement or focus determines the subsequent diagnostic pathway.

LONG Q3. Discuss enhancement kinetics in Breast MRI and their significance.

Answer:

Enhancement kinetics should be evaluated for each lesion.

They are divided into:

A. Initial phase

The initial phase occurs within the first 2 minutes.

Slow

• <50% increase in signal intensity.

Medium

• 50–100% increase.

Fast

• 100% increase.

B. Delayed phase

Persistent

• Enhancement continuously increases.

Plateau

• No significant change after the initial phase.

Washout

• Signal intensity decreases.

Importance

• Washout may be associated with malignancy.
• However, kinetic patterns alone are not sufficiently reliable.
• A single lesion may display different kinetic patterns.
• Some studies have not found kinetics to be significant predictors of malignancy.
• Therefore lesion morphology should be given greater importance.

CAD

CAD evaluates contrast kinetics automatically and displays enhancement curves/peak enhancement.

In the slide’s color convention:

• Red = type 3 washout
• It is considered the suspicious/worst area.

PART II — BASICS OF CARDIAC MRI

The Cardiac MRI slides define cardiac MRI as MRI used to study heart anatomy, physiology and pathology. Advantages include improved soft-tissue definition, tailored protocols, functional assessment and absence of ionizing radiation.

A. 5-MARK SHORT QUESTIONS — CARDIAC MRI

Q38. What are the advantages of Cardiac MRI?

Answer

1. Improved soft-tissue definition.
2. Protocol can be tailored according to differential diagnosis.
3. Large number of imaging sequences are available.
4. Dynamic imaging provides functional assessment.
5. There is no ionizing radiation, although MRI safety must still be considered.

Q39. Describe patient management during Cardiac MRI.

Answer

Coil

• Cardiac or torso phased-array coil in adults.
• Head coil in infants.

ECG leads

• Leads should not form loops.
• Cables should be aligned parallel to the bore.
• Wider spacing gives better ECG signal.
• Narrower spacing produces fewer gradient-related artifacts.

Position

• ECG lead position may be anterior or posterior.

Q40. What is cardiac gating?

Answer

Cardiac gating synchronizes MRI data acquisition with the cardiac cycle.

Two methods are:

1. Prospective gating
2. Retrospective gating

It is important for reducing cardiac-motion-related artifacts and for evaluating cardiac motion and function.

Q41. Differentiate prospective and retrospective cardiac gating.

Answer

Q42. What are the major MR imaging techniques in Cardiac MRI?

Answer

The major techniques include:

1. Dark/black blood imaging
2. Bright/white blood imaging
3. Imaging sequences
4. Imaging planes
5. Phase-contrast imaging
6. Delayed enhancement imaging
7. Gadolinium-assisted MR angiography.

Q43. What is black-blood imaging?

Answer

Black-blood imaging uses sequences that null the signal from flowing blood.

It is used to demonstrate:

• Cardiac anatomy
• Pericardial abnormalities
• Mediastinal abnormalities
• Extra-luminal aortic disease

Sequences include ECG-gated spin echo/fast spin echo and inversion-recovery techniques.

Q44. How is blood nulled in conventional black-blood imaging?

Answer

Blood nulling occurs because:

1. Flowing blood moves through the imaging slice.
2. It does not experience both the 90° and 180° RF pulses.
3. Therefore its signal becomes suppressed.
4. Longer TE helps blood nulling.
5. Thin slices, orthogonal slice positioning relative to flow and systolic acquisition also help.

Q45. What is bright-blood imaging?

Answer

Bright-blood imaging:

1. Shows fast-flowing blood with high signal intensity.
2. Is commonly used to evaluate cardiac function.
3. Uses GRE and SSFP sequences.
4. Includes sequences such as SPGR, turbo FLASH and FFE.
5. SSFP provides high SNR and contrast-to-noise ratio and can be performed rapidly.

Q46. What is SSFP?

Answer

SSFP means steady-state free precession.

In SSFP:

1. Residual transverse magnetization is used for subsequent excitations.
2. RF pulses move the magnetization vector back and forth across the z-axis.
3. Both transverse and longitudinal magnetization reach a steady state.
4. It produces increased SNR.
5. It permits very rapid imaging with short TR.

Q47. What are the advantages of SSFP?

Answer

1. Uses residual transverse magnetization instead of wasting it.
2. Provides increased SNR.
3. Steady state is reached rapidly.
4. TRs can be extremely short.
5. It provides good contrast-to-noise and SNR compared with GRE.

Q48. What is cine imaging?

Answer

Cine MRI is an MRI technique used to capture motion.

In cardiac cine imaging:

1. Images are acquired at multiple time points throughout the cardiac cycle.
2. Acquisition is synchronized with ECG.
3. Separate k-spaces are assigned to different cardiac phases.
4. Images are reconstructed from the different k-spaces.
5. The images are displayed as a movie.

Q49. What is phase-contrast MRI?

Answer

Phase-contrast imaging produces:

1. Magnitude images
2. Phase images

It is important for:

• Quantitative flow measurement.
• Measurement of velocity.
• Measurement of volume.

Q50. What is delayed enhancement imaging in Cardiac MRI?

Answer

Delayed enhancement imaging is used for assessment of myocardial viability and scar.

According to the slides:

• It is a T1-weighted gradient-echo technique.
• Images are obtained approximately 10 minutes after gadolinium.
• Focal myocardial fibrosis has delayed gadolinium washout.
• Hyperenhancement indicates myocardial scar.
• This may represent an evolved myocardial infarction.

Q51. What are the standard cardiac imaging planes?

Answer

Important cardiac planes include:

1. Short-axis
2. Two-chamber view
3. Four-chamber view
4. Left ventricular outflow tract (LVOT) view
5. Horizontal and vertical long-axis views.

Q52. What are the two main types of planes used in Cardiac MRI?

Answer

1. Body/scanner planes
   • Axial
   • Sagittal
   • Coronal
2. Cardiac planes

Body planes are oriented orthogonal to the long axis of the body.

Q53. What are the uses of axial, sagittal and coronal planes in cardiac MRI?

Answer

• Axial plane: depicts the four chambers and pericardium simultaneously.
• Sagittal plane: demonstrates great vessels arising continuously from the ventricles.
• Coronal plane: assesses the LV outflow tract, left atrium and pulmonary veins.

Q54. What are the indications of Cardiac MRI?

Answer

Major indications include:

Ischemic heart disease

• Myocardial viability.
• Myocardial perfusion.
• Bypass graft patency.
• Global and regional ventricular function.
• Ventricular volume.
• Ejection fraction.
• Ventricular mass.

Other indications

• Congenital heart disease.
• Pericardial disease.
• Cardiomyopathy.
• Valvular heart disease.
• Cardiac and extracardiac masses.
• Aortic, renal and peripheral vascular diseases.

15-MARK LONG QUESTIONS — CARDIAC MRI

LONG Q4. Describe the major cardiac MRI imaging techniques.

Answer:

Cardiac MRI uses several imaging techniques.

1. Black-blood imaging

Flowing blood signal is suppressed.

Uses:

• Cardiac anatomy.
• Pericardial abnormalities.
• Mediastinal abnormalities.
• Extra-luminal aortic disease.

Sequences include spin echo, fast/turbo spin echo and inversion recovery.

2. Bright-blood imaging

Fast-flowing blood appears bright.

Uses:

• Cardiac function.
• Cardiac motion.
• Valvular disease.

Sequences include:

• GRE.
• SSFP.

3. Cine imaging

• Captures cardiac motion.
• Uses ECG synchronization.
• Acquires multiple phases of the cardiac cycle.
• Reconstructs images into a movie.

4. Phase contrast

Provides:

• Magnitude images.
• Phase images.
• Quantitative flow.
• Velocity and volume measurements.

5. Contrast-enhanced imaging

Perfusion/first-pass imaging and delayed enhancement are used for myocardial assessment.

Delayed enhancement approximately 10 minutes after gadolinium demonstrates myocardial scar/fibrosis as hyperenhancement.

LONG Q5. Explain cardiac gating and its importance in Cardiac MRI.

Answer:

Cardiac gating synchronizes MRI acquisition with the cardiac cycle.

Prospective gating

• R wave triggers data acquisition.
• RF excitation is continuous.
• Data acquisition is not continuous.
• Blood-flow measurement is not possible.

Retrospective gating

• Data acquisition is continuous.
• Data are assigned retrospectively to images.
• Useful in patients with arrhythmias.
• Allows measurement of blood flow throughout the cardiac cycle.
• It is more time-consuming.

Importance

Gating of white-blood images:

• Allows evaluation of dynamic cardiac function.
• Evaluates myocardial motion.
• Evaluates valve leaflet motion.
• Times acquisition during diastole.
• Reduces cardiac-motion artifacts.

LONG Q6. Describe SSFP, its principle and advantages.

Answer:

SSFP stands for steady-state free precession.

Principle

• Residual transverse magnetization is retained.
• It contributes signal to subsequent RF excitations.
• The initial RF pulse tilts magnetization partially into the transverse plane.
• Subsequent RF pulses move the magnetization vector back and forth across the z-axis.
• Both transverse and longitudinal magnetization reach a steady state.

Signal characteristics

The images have both T1- and T2-weighted characteristics.

Bright signal in steady-state white-blood imaging is attributable to T1 and T2 signal from blood rather than being purely flow-related.

Advantages

• Increased SNR.
• Faster achievement of steady state.
• Very short TR.
• Rapid imaging.
• Greater contrast-to-noise and SNR than GRE sequences.

PART III — MRCP

MRCP is a non-invasive MRI technique used to investigate the biliary and pancreatic systems. It was introduced in 1991 and uses heavily T2-weighted fast spin-echo sequences.

A. 5-MARK SHORT QUESTIONS — MRCP

Q55. Define MRCP.

Answer

MRCP stands for Magnetic Resonance Cholangiopancreatography.

It:

1. Is an MRI technique for evaluating the pancreatobiliary system.
2. Produces images similar in appearance to ERCP.
3. Uses heavily T2-weighted fast spin-echo sequences.
4. Is non-invasive.
5. Is a sensitive and less costly alternative to diagnostic ERCP.

Q56. Explain the principle of MRCP.

Answer

MRCP uses heavily T2-weighted sequences.

1. Bile and pancreatic secretions have long T2 relaxation times.
2. They therefore produce high signal and appear bright.
3. Surrounding soft tissue has shorter T2 and appears darker.
4. Blood vessels have no measurable signal in the described MRCP technique.
5. This natural contrast allows visualization of fluid-filled structures such as the gallbladder, bile ducts and pancreatic duct.

Q57. Why does fluid appear bright on MRCP?

Answer

1. MRCP uses heavily T2-weighted sequences.
2. Static or slow-moving fluid has a long T2 relaxation time.
3. Therefore it retains high T2 signal.
4. Bile and pancreatic secretions appear bright.
5. Surrounding tissues have shorter T2 and therefore appear relatively dark.

Q58. What are the advantages of MRCP over conventional invasive cholangiography?

Answer

MRCP is:

1. Non-invasive
2. Radiation-free
3. Diagnostic
4. Multiplanar
5. Associated with no post-procedure complications as described in the MRCP-vs-ERCP comparison.

Q59. Describe patient preparation for MRCP.

Answer

1. Patient should be fasted for 4 hours.
2. Fasting reduces stomach and duodenal fluid secretion.
3. It reduces bowel peristalsis.
4. It promotes gallbladder distension.
5. Clear fluids and routine medication are permitted as described in the slides.

Q60. What are the breathing instructions in MRCP?

Answer

The patient should:

1. Be instructed about specific breathing instructions.
2. Listen to the radiographer through headphones/speaker.
3. Suspend expiration when instructed.
4. Perform adequate breath holding during appropriate sequences.
5. Poor breath holding can cause the CBD and main pancreatic duct to appear not to unite or appear stenotic/dilated.

Q61. What are the indications of MRCP?

Answer

Biliary diseases

• Choledochal cyst.
• Choledochocele.
• Caroli disease.
• Congenital duct variants.
• Choledocholithiasis.
• Primary sclerosing cholangitis.
• Post-surgical biliary complications.
• Cholangiocarcinoma.

Pancreatic diseases

• Pancreatic divisum.
• Chronic pancreatitis.
• Pancreatic cancer.

Q62. What are the contraindications of MRI/MRCP mentioned in the slides?

Answer

The slides mention:

1. Electrically, magnetically or mechanically activated implants.
2. Intracranial aneurysm clips unless titanium.
3. Pregnancy where risk-benefit must be assessed.
4. Ferromagnetic surgical clips/staples.
5. Metallic foreign body in the eye.
6. Metal shrapnel or bullet.

Q63. What is the importance of oral contrast in MRCP?

Answer

A limitation of MRCP is overlap between high signal from the pancreatobiliary system and the gastrointestinal tract.

Oral negative contrast can:

1. Reduce bowel signal.
2. Shorten T2 relaxation time.
3. Reduce T2 signal from bowel fluid.
4. Improve image quality.
5. Improve visualization of bile and pancreatic ducts without superimposed gastrointestinal high signal.

Q64. What is negative oral contrast?

Answer

Negative oral contrast:

1. Appears predominantly dark on MRI.
2. May consist of small particulate aggregates such as superparamagnetic iron oxide.
3. Produces local field inhomogeneities.
4. Shortens T1 and T2 relaxation times.
5. Reduces signal from gastrointestinal contents.

Q65. What is the role of blueberry juice in MRCP?

Answer

According to the slides:

1. Blueberry juice is inexpensive.
2. It has relatively high manganese content.
3. Its paramagnetic properties shorten T2 and T1 recovery times.
4. It suppresses stomach and duodenal signal on T2-weighted MRCP.
5. It can therefore act as a negative oral contrast agent on T2-weighted imaging.

Q66. What is the role of pineapple juice in MRCP?

Answer

1. Pineapple juice can act as a negative oral contrast agent.
2. It shortens T2 relaxation time.
3. This reduces signal from gastrointestinal fluid.
4. The effect is associated with its relatively high manganese concentration.
5. The reduction in bowel signal improves visualization of the pancreatobiliary system.

Q67. What sequences are used for MRCP?

Answer

Earlier GRE and FSE sequences were used, but they suffered from motion artifacts and poor spatial resolution.

The slides describe heavy T2-weighted modified FSE techniques:

• RARE
• HASTE
• FRFSE

These ultrafast techniques acquire images rapidly with reduced artifacts.

Q68. What is the purpose of the MRCP localizer?

Answer

1. A three-plane TrueFISP localizer is obtained initially.
2. It is used to localize abdominal structures.
3. It helps plan subsequent sequences.
4. It is a fast single-shot technique.
5. Its acquisition time is less than approximately 25 seconds according to the slide.

Q69. Describe T2 HASTE/TrueFISP coronal imaging in MRCP.

Answer

1. Plan coronal slices using the axial localizer.
2. Position the block across the liver.
3. Cover the entire liver from anterior to posterior abdominal wall.
4. Use right-to-left phase direction to reduce cardiac artifacts.
5. Use phase oversampling to prevent wrap-around artifacts and instruct the patient to breath-hold.

Q70. What is Secretin-stimulated MRCP?

Answer

Secretin is:

1. An endogenous hormone normally produced by the duodenum.
2. It stimulates exocrine pancreatic secretion.
3. Synthetic secretin given intravenously increases pancreatic duct calibre.
4. This improves visualization of the pancreatic duct.
5. MRCP is performed at baseline and at specified intervals after injection.

Q71. What are the indications of Secretin-stimulated MRCP?

Answer

It is used for:

1. Detection and characterization of pancreatic duct anomalies and strictures.
2. Evaluation of pancreatic duct integrity.
3. Demonstration of communication between pancreatic duct and pseudocyst/fistula.
4. Assessment of pancreatic function.
5. Assessment of sphincter of Oddi dysfunction.

Q72. What is functional MR cholangiography?

Answer

Functional MR cholangiography uses MR lipophilic paramagnetic contrast agents that undergo hepatobiliary excretion.

Examples listed are:

• Gadobenate dimeglumine — Gd-BOPTA.
• Gd-EOB-DTPA.
• Mangafodipir trisodium.

Delayed imaging produces hyperintense bile on 3D T1-weighted fat-saturated GRE images.

Q73. What are the advantages of functional MR cholangiography?

Answer

It:

1. Demonstrates communication between cystic lesions and draining bile ducts.
2. Helps diagnose congenital biliary disorders such as Caroli disease.
3. Helps distinguish true obstruction from pseudo-obstruction.
4. Can demonstrate active contrast extravasation in suspected bile leaks.
5. Provides better bile-duct delineation due to high SNR.

Q74. What are the limitations of MRCP?

Answer

1. MRCP is diagnostic only.
2. Small/impacted calculi may be missed.
3. Air and metallic artifacts may limit duct visualization.
4. Volume averaging may obscure small calculi.
5. Motion, gas, clot, metallic clips and pulsation can cause artifacts.
6. Respiratory motion may simulate stones/strictures.
7. Hepatic artery pulsatility may simulate a common duct stricture.
8. Certain metallic implants prevent MRI.
9. Duodenal fluid may obscure the common duct if negative contrast is not used.

15-MARK LONG QUESTIONS — MRCP

LONG Q7. Describe MRCP including principle, preparation, technique and sequences.

Answer:

Definition

MRCP is a non-invasive MRI technique used to investigate the biliary and pancreatic systems. It produces images similar to invasive cholangiographic methods such as ERCP.

Principle

MRCP uses heavily T2-weighted sequences.

• Bile and pancreatic secretions have long T2.
• They appear bright.
• Surrounding soft tissue has shorter T2 and appears dark.
• This provides natural contrast between fluid-filled ducts and surrounding tissue.

Patient preparation

• Fast for 4 hours.
• Reduces gastric/duodenal secretions.
• Reduces bowel peristalsis.
• Promotes gallbladder distension.
• Clear fluids and routine medication are allowed according to the slides.

Breathing

The patient receives breathing instructions and breath-holds during relevant sequences.

Poor breath holding may create apparent CBD/pancreatic duct abnormalities.

Sequences

Modern MRCP uses heavily T2-weighted modified FSE sequences:

• RARE
• HASTE
• FRFSE

These provide rapid acquisition with reduced motion artifacts.

Positioning

• Patient supine.
• Posterior spine coil/body coil used.
• Body coil covers upper abdomen.
• Respiratory bellows are positioned at the point of maximum respiratory excursion.

LONG Q8. Discuss the complete MRCP protocol.

Answer:

1. Localizer

A three-plane TrueFISP localizer is first acquired.

• Rapid single-shot.
• Used for localization and sequence planning.
• Acquisition time <25 seconds.

2. T2 TrueFISP/HASTE coronal

• Plan from axial localizer.
• Cover entire liver.
• Right-to-left phase direction.
• Phase oversampling to avoid wrap-around.
• Breath holding.

3. T2 TrueFISP axial

• Plan on coronal TrueFISP.
• Cover entire biliary system.
• Coverage extends from diaphragm to C-loop of duodenum.
• Breath hold.
• Planning should be performed on breath-hold coronal imaging because diaphragm movement changes liver position.

4. T2 HASTE fat-sat axial

• Similar coverage of the biliary system.
• Breath-hold acquisition.
• Used to obtain heavily T2-weighted images.

5. Thick-slab HASTE coronal oblique

• Thick 40-mm slab.
• Planned across the CBD.
• Rotated approximately 20–30° clockwise to include CBD and gallbladder.
• Phase oversampling is used.
• Breath holding is required.

6. 3D T2 TSE/SPACE

• Coronal 3D acquisition.
• Covers CBD, pancreatic duct and gallbladder.
• Respiratory navigator can be used.
• Navigator box is positioned over the right hemidiaphragm/right liver-lung interface.
• Patient should breathe gently throughout.

LONG Q9. Explain Secretin-stimulated MRCP in detail.

Answer:

Definition

Secretin is an endogenous hormone produced by the duodenum that stimulates pancreatic exocrine secretion.

Principle

When synthetic secretin is administered intravenously:

• Pancreatic secretion increases.
• Pancreatic duct calibre increases.
• Visualization of the pancreatic duct improves.

Technique

A thick-slab MRCP is obtained:

• At baseline.
• At 1 minute.
• 3 minutes.
• 5 minutes.
• 7 minutes.
• 9 minutes after injection.

The effect begins almost immediately and peaks between approximately 2–5 minutes.

By approximately 10 minutes:

• Main pancreatic duct calibre should return toward baseline.
• Persistent duct dilatation >3 mm is considered abnormal according to the slide.

Indications

1. Pancreatic duct anomalies.
2. Pancreatic duct strictures.
3. Evaluation of duct integrity.
4. Communication with pseudocysts/fistulas.
5. Pancreatic function and sphincter of Oddi dysfunction.

LONG Q10. Compare MRCP and ERCP.

Answer:

Important conclusion

MRCP is particularly useful as a non-invasive diagnostic technique, while ERCP has the important advantage of being therapeutic as well as diagnostic. The slides note that at some institutions MRCP has replaced diagnostic ERCP, with ERCP reserved for therapeutic interventions.

THE MOST IMPORTANT 15-MARK QUESTIONS TO MEMORIZE

1. Breast MRI

“Describe indications, patient positioning, protocol and contrast administration of Breast MRI.”

2. Breast MRI

“Describe BI-RADS characterization of breast lesions on MRI — mass, non-mass-like enhancement and focus.”

3. Breast MRI

“Explain enhancement kinetics and CAD in Breast MRI.”

4. Cardiac MRI

“Describe black-blood, bright-blood, cine, phase-contrast and contrast-enhanced cardiac MRI.”

5. Cardiac MRI

“Explain cardiac gating and differentiate prospective and retrospective gating.”

6. MRCP

“Describe MRCP principle, patient preparation, protocol, sequences and technique.”

If you know these six thoroughly, you have covered a very large proportion of the examinable material in the three decks.

ULTRA-HIGH-YIELD 5-MARK QUESTIONS

1. Indications of Breast MRI
2. Goals of breast MRI staging
3. Breast MRI patient positioning
4. Breast MRI protocol
5. Breast MRI contrast protocol
6. Normal enhancing structures of the breast
7. Normal fibroglandular enhancement
8. BI-RADS categories: mass, non-mass-like enhancement and focus
9. Definition and characteristics of a mass
10. Mass shape and margin descriptors
11. Benign MRI mass characteristics
12. Rim enhancement
13. Initial enhancement kinetics
14. Delayed enhancement kinetics
15. Computer-aided detection
16. Non-mass-like enhancement
17. Focus
18. BI-RADS assessment categories
19. Black-blood imaging
20. Bright-blood imaging
21. Prospective vs retrospective gating
22. SSFP
23. Cine imaging
24. Phase-contrast MRI
25. Delayed enhancement
26. Cardiac MRI planes
27. Indications of cardiac MRI
28. Definition/principle of MRCP
29. Patient preparation for MRCP
30. MRCP indications
31. MRCP contraindications
32. Oral contrast in MRCP
33. Negative oral contrast
34. Blueberry/pineapple juice
35. MRCP sequences
36. MRCP localizer
37. Secretin-stimulated MRCP
38. Indications of Secretin MRCP
39. Functional MR cholangiography
40. MRCP vs ERCP
41. Limitations of MRCP

LAST-MINUTE MEMORY SHEET

Breast MRI

Indications → Screening → Diagnosis → Staging → Treatment

BI-RADS lesion types →

Mass → NME → Focus

Mass →

Shape → Margin → Internal enhancement

Shape →

Round → Oval → Lobular → Irregular

Margin →

Smooth → Irregular → Spiculated

Kinetics →

Initial: Slow <50 | Medium 50–100 | Fast >100

Delayed: Persistent | Plateau | Washout

Focus →

<5 mm

BI-RADS →

0 Incomplete
1 Negative
2 Benign
3 Probably benign
4 Suspicious
5 Highly suspicious
6 Biopsy-proven malignancy.

Cardiac MRI

Two blood techniques →

Black blood + Bright blood

Black blood →

Anatomy + Pericardium + Mediastinum + Aortic wall/extraluminal disease

Bright blood →

Flow + Motion + Function + Valves

Gating →

Prospective vs Retrospective

Cine →

Motion through cardiac cycle

Phase contrast →

Flow + Velocity + Volume

Delayed enhancement →

Scar/Fibrosis/Infarction

Planes →

Short axis + 2 chamber + 4 chamber + LVOT.

MRCP

Principle →

Heavily T2 → fluid bright

Preparation →

4-hour fasting

Main sequences →

RARE + HASTE + FRFSE

Protocol →

Localizer → Coronal → Axial → Thick slab → 3D

Secretin →

Pancreatic secretion ↑ → duct calibre ↑ → visualization ↑

MRCP vs ERCP →

MRCP = non-invasive + diagnostic
ERCP = invasive + diagnostic + therapeutic

Limitations →

Small stones + motion + gas + metal + volume averaging + pulsation.

2-DAY STUDY PLAN

DAY 1 — Breast MRI + Cardiac MRI

Morning

• Memorize Breast MRI short Q1–Q37.
• Give special attention to:
  • indications
  • protocol
  • mass
  • BI-RADS
  • kinetics
  • NME
  • focus.

Afternoon

• Memorize Breast MRI Long Q1–Q3.

Evening

• Cardiac MRI short Q38–Q54.
• Memorize:
  • black blood
  • bright blood
  • gating
  • SSFP
  • cine
  • phase contrast.

Night

• Memorize Cardiac Long Q4–Q6.

DAY 2 — MRCP + Revision

Morning

• MRCP short Q55–Q74.

Afternoon

• MRCP Long Q7–Q10.

Evening
Do active recall, not reading:

Close the answers and try to reproduce:

1. Breast MRI indications.
2. Breast MRI protocol.
3. Mass descriptors.
4. Kinetic curves.
5. Focus.
6. Cardiac gating.
7. Black vs bright blood.
8. SSFP.
9. Cardiac planes.
10. MRCP principle.
11. MRCP protocol.
12. Secretin MRCP.
13. MRCP vs ERCP.
14. MRCP limitations.