RADS 301 Midterm 2 review

based off review slide deck

What are special considerations in the relationship between parent/family, child patient, and imager in pediatric imaging?

• interactions with parents rather than patients (parents are inquisitive and protective so increased questions and explanations occur)

• requires higher professionalism and effective communication (area of highest complaints in pediatric medicine)

What are special considerations in age-related changes in imaging appearance in pediatric imaging?

• requires familiarity with age-based appearnace of the anatomy in all organ systems

• understand continuous changes in appearance that are due to normal development that can be mistaken as pathology

  • example: neonate/young child’s thyroid can be mistaken for a mass

  • unfused growth plates in bones of pediatric patient may be mistaken as a fracture

What are special considerations in radiation safety in pediatric imaging?

• pediatric tissues are more sensitive

• longer life expectancy to manifest radiation-induced mutations

• ALARA principle of radiation protection, limit ionizing radiation dose as low as reasonably achievable

• use imaging modalities without radiation

• do not overreact to small radiation doses, just weigh risk vs benefit

What are the current statistics of cancer in Canada?

• leading cause of death in Canada

• estimated 2 in 5 canadians will be diagnosed with cancer in their lifetime and 1 in 4 will die from cancer

What 4 cancers account for 46% of all new cancer cases and what are their 5-year net survival rates?

4 cancers and survival rates:

• lung cancer (13% of cases and 26% survival rate)

• prostate cancer (20% of cases and 90% survival rate)

• breast cancer (25% of cases and 89% survival rate)

• colorectal cancer (10% of cases and 67% survival rate)

How is PET-CT used in oncology?

• used to detect metastasis and cancer staging

• assess effectiveness of treatments

• need to use a different radiotracer for different tissues

What is interventional radiology?

use of imaging to direct specialized catheters throughout the body to effect minimally invasive therapies

• open blockages

• block openings

• drain pus, blood, fluid, cells, protein

• remove stones and foreign bodies

When are interventional radiology procedures applied?

• when imaging procedures are less intrusive than conventional therapies

  • less intrusive, shorter recovery, avoids complications

• treat disorders not amenable to surgical/medical treatment

  • ex: embolization of AVM

What are the benefits of interventional radiology?

• minimally invasive nature

• reduced risk compared to traditional surgery

• shorter recovery times

• improved patient outcomes

• potential cost savings

What are uterine fibroids?

• benign growths on the uterus

• 30-40% of women over 35 have these

What are the options to treat uterine fibroids with pros and cons?

• hysterectomy (curative but irreversible)

• myomectomy (maintains fertility potential but higher morbidity due to significant blood loss and may not treat culprit fibroids)

• hormonal therapy (fibroids recur after discontinuation)

What is the interventional radiology alternative treatment for uterine fibroids?

uterine artery embolization

• uses injection through catheter to the uterine artery

• plugs uterine artery with polyvinyl particles to restrict bloodflow to fibroids, killing them

How is interventional radiology used in spinal pain management?

epidural steroid injections

What are the IR procedures offered for stroke thrombectomy?

• Endovascular thrombectomy for acute stroke

• carotid stenting for stenosis, dissection, or occlusion

• aneurysm repair with coiling or flow diversion

• embolization of dural arteriovenous fistulae and arteriovenous malformations

• pre-operative tumour embolization

• vertebroplasty and rhizotomy

• percutaneous spine injections

What is Large Vessel Occlusion?

• carotid terminus, M1, A1, proximal M2, or basilar

• potential EVT target

How does EVT work?

• insert catheter into artery

• use imaging to guide catheter up to site of clot in the brain

• stent retriever or suction device captures and removes clot, restoring blood flow

When would carotid stenting be preferred?

• previous neck surgery or radiation

• very deep (retropharyngeal) carotid or large body habitus

• high perioperative risk for general anesthetic

• age less than 70 years

What is vertebroplasty?

• a minimally invasive medical procedure that injects medical-grade bone cement into a cracked or compressed spinal bone (vertebra) to stabilize the spine and relieve pain

• treats compression fractures and persistent back pain

What are the basic steps of the vertebroplasty procedure?

• conscious sedation by anesthesia

• 1% lidocaine down to pedicle periosteum

• centre pedicle between endplates, oblique toward pedicle

• 13G 4” or 6” bevel tip bone access needle down pedicle, avoid medial cortex

• advance to anterior 1/3 of the vertebral body on lateral

• check needle tip on true AP, if not reached midline then consider access from other pedicle

• inject cement under continuous AP and lateral fluoro

• watch for intravasation, posterior extension, spread through endplates

What are the liver functions?

• remove potentially toxic byproducts of certain medications

• metabolizes nutrients from food to produce energy when needed

• helps your body fight infections by removing bacteria from blood

• produces most of the substances that regulate blood clotting

• produces bile to digest fat and absorb vitamins

• produces most proteins needed by the body

• prevents shortages of nutrients by storing vitamins, minerals, and sugar

What are common liver diseases?

• Metabolic dysfunction-associated steatotic liver disease (MASLD, used to be called NAFLD)

• hepatocellular carcinoma (HCC)

What is MASLD?

• Metabolic dysfunction-associated steatotic liver disease

• condition characterized by excessive fat build up in the liver (steatosis) in the absence of excessive alcohol intake

• risk factors are T2D, obesity, and metabolic syndrome

MASLD prevalence?

20-30% of population in Western countries (8 million Canadians)

Clinical indications of MASLD

• can present as steatosis alone or can lead to fibrosis, inflammation (steatohepatitis/MASH), cirrhosis, or cancer

• leads to decreased quality of life and increased risk of mortality

MASLD Screening

• can detect disease early

• blood tests for liver enzymes like AST and ALT lack sensitivity

  • normal in about 78% of patients with MASLD

Pros and cons of screening MASLD by conventional ultrasound

Pros:

• acceptable specificity and sensitivity if there is sufficient steatosis

• non-invasive

• low cost

• readily available

• no radiation

Cons:

• body habitus (overall physique) affects scan quality and sensitivity and specificity

• operator dependent

US liver fat quantification

• quantify the attenuation of the sound beam (dB/cm/MHz) to determine liver fat

• commercially available

Pros and cons of screening MASLD by ultrasound elastography techniques (ex: shear wave, transient, etc.)

Pros:

• can measure extent of the liver stiffness to determine stage of disease

Cons

• body habitus can affect scan quality

MASLD screening by CT imaging

Not generally considered for MASLD screening due to the cons:

• higher cost

• less availability

• substantial radiation exposure

MASLD screening by MRI imaging

Generally not considered for MASLD screening due to the cons:

• higher cost

• less availability

Should we screen for MASLD?

general consensus from world guidelines is that it is not recommended

• unclear benefit from treatment options

• unclear value of screening tests

• unclear cost-effectiveness

Who is MASLD screening recommended for?

Blood work/imaging screening recommended for patients with: obesity, metabolic syndrome, diabetes, elevated liver enzymes, T2D, other cardiometabolic risk factors, hepatic steatosis, family history of MASLD cirrhosis, people with chronic elevated liver tests should be screened for advanced fibrosis.

What is hepatocellular carcinoma (HCC)?

• most common form of liver cancer

• risk factors include cirrhosis, Hepatitis B and C, alcohol intake, MASLD, etc.

• third leading cause of cancer-related death in 2020

Ultrasound screening for HCC

Imaging modality of choice

• Pros: inexpensive, non-invasive, well-tolerated, readily available

• Cons: sensity is operator dependent, some areas of liver are harder to visualize using ultrasound, lower sensitivity to early-stage HCC, body habitus has an effect

Contrast enhanced CT screening for HCC

• Pros: higher sensitivity, better at detecting early-stage HCC

• Cons: ionizing radiation exposure, adverse events due to contrast agents, expensive

MRI screening for HCC

• pros: higher sensitivity, better at detecting early-stage HCC

• cons: expensive, time-consuming, patients may be claustrophobic or have implants that are incompatible with MRI

Abbreviated MRI screening for HCC

• pros: higher sensitivity, better at detecting early-stage HCC, less time, more cost-effective than conventional MRIs

• cons: relatively low amount of data compared to ultrasounds, requires a recall for a complete exam

Should we screen for HCC?

• patients with cirrhosis should be screened by ultrasound every 6 months

• only early HCC can be cured, and best survival rate is seen in patients who receive early diagnoses

• RCT by Zhang et al. found that screening patients with Hep B improved early detection, receipt of curative treatment, and improved overall survival.

Should we screen patients without cirrhosis for HCC?

recommended for patients with:

• Hep C and advanced fibrosis

• Chronic Hep B

• Family history of HCC

• Patients of Asian or African descent

Smoking and lung cancer statistics

• ~90% of lung cancer cases were a result of smoking tobacco

• based on 2022 data: 10.9% are smokers, 23.2% are former smokers, and 34% combined are either former or current smokers

How does smoking history affect lung cancer?

• heavy smoking leads to greater risk

• smoking history is measured in pack-years = product of the average number of packs smoked daily and number of years smoking

  • patient who smokes one pack a day for 30 years has same pack-year history as someone who smokes two packs a day for 15 years.

Clinical features of lung cancer

• 50% of cases are asymptomatic

• cough and dyspnea (non-specific symptoms) are common among lung cancer patients

• hemoptysis

• pleuritic chest pain

• wheeze

• pneumonia

• pleural effusion

• lymphadenopathy

symptoms may be secondary to metastases or paraneoplastic syndromes

Why should we screen for lung cancer?

• cancer is usually asymptomatic until disease has spread to an advanced stage

• early detecting disease before clinical manifestation leads to better response to treatment, more treatment options, better chances of success

• lung cancer has poor prognosis

• half of lung cancer cases in Canada are diagnosed at stage IV

  • 5 year survival rate for stage 1 is 62% while for stage IV it is ~3%

Who to screen for lung cancer?

• populations who are at high risk for lung cancer and not yet experiencing any symptoms

• ages 55 to 74 years old

• currently smokes or smoked less than 15 years ago

• smoking history of 30 pack years or more

How to screen for lung cancer?

• low-dose CT

• safe and effective way to screen for more info than a chest x-ray

• screen every year for 3 consecutive years

What is low-dose CT?

• similar to routine non-contrast CT scans

• radiation dose to screening participants must be minimized while still providing diagnostic quality examinations

• scan parameters:

  • performed in a single breath hold

  • performed without IV or oral contrast

  • scan range: lung apices to costophrenic sulci

technique should be set to a CT dose index of 50 mGy or less for a standard 70-kg patient

What are the pulmonary nodules we screen for on CT?

• looking for non-calcified pulmonary nodule

• nodule types: solid, subsolid (ground glass, part-solid)

Probability of malignancy in lung nodules

• subsolid nodules have a higher risk of malignancy

• prevalence of malignancy was 59% for non-solid nodules, 48% for part-solid nodules, 11% for solid nodules

• growth rate of non-solid nodules is considerably slower than solid lesions.

Nodule measurement

• measure size and growth of nodules to determine management of pulmonary nodules detected on screenings ( can be manual measurement of volumetric diameter or volumetric measurement)

• size and shape affects accuracy of volumetric measurements

• volumetric measurements show higher error for elongated shapes than circular shapes

Subsolid nodule measurement

• measuring subsolid nodules is more complex

• stable in diameter but solid component is expanding

• increased nodule size happens when mean diameter increases by 2mm or more for nodules under 15mm OR by 15% in mean diameter for nodules larger than 15mm

Biggest environmental impact opportunities in healthcare

• upgrade light bulbs for low impact (<0.2 tCO2e/year)

• recycle for moderate impact (0.2-0.8 tCO2e/year)

• high impact (>0.8 tCO2e/year) is plant based diet, avoid one transatlantic flight, or live car free

Biggest environmental impact opportunities as an individual

• active transportation: walk, bike, transit, and fly less

• electrification: heat, hot water, cooking

• plant-forward food: minimally processed and mostly plant-sourced

• investments: divest from fossil fuels and invest in personal or institutional funds

Emissions and waste in radiology department of healthcare

• education: health impacts, health benefits, research, sustainable QI

• energy use: MRI and CT, PACs, laser printers, lights

• food for staff and patients

Emissions and waste in facility/system of healthcare

• buildings: room climate control, chiller systems for MIE

• supply chain: medical imaging equipment, contrast, gowns, linens, sharps containers, single use plastics, procurement contract (RFP)

• transportation: commute, conference travel

Emisions per study by modality from lowest to highest

X-ray, ultrasound, CT, SPECT, MRI, PET, interventional

Contribution of health care to climate change

• healthcare = 4.6% of Canada’s greenhouse gas emissions

• medical imaging = 0.8-1% of global greenhouse gas emissions

NHS net zero scopes

• Scope 1 (direct, 17%): building heating, anesthetic gases

• Scope 2 (indirect, 12%): purchased energy

• Scope 3 (indirect, 71%): supply chain

Canadian Association of Radiologists statement on Planetary Health Education in Radiology

• climate crisis directly impacts Canadians’ health

• healthcare sector accounts for 4.6% of Canada’s GHG emissions

• transformation of Canadian healthcare system to be eco-friendly is enhanced by physician leadership

• integration of planetary health education is essential to position radiologists for climate mitigation and adaptation leadership

Screening test vs Diagnostic test

Screening: detection of potential disease in ASYMPTOMATIC individuals

Diagnostic: aiding formal diagnosis in SYMPTOMATIC individuals

What are the benefits of early screening?

• proactive approach (secondary vs tertiary prevention)

  • secondary = identify disease early to mitigate complications

  • tertiary = improving quality of life in those with disease after diagnosis

• early referral and holistic approach to treatment (conservative, medical, interventions)

• support networks, advanced planning, and goals of care

What makes a good screening test?

Highly sensitive test rules out disease = Snout

Highly specific test rules in disease = Spin

• Best screening tests have High Sn and variable sp to effectively rule out likelihood of having that disease

• asymptomatic, unknown = want to pick up cases

What makes a good diagnostic test?

Highly sensitive test rules out disease = Snout

Highly specific test rules in disease = Spin

• Best diagnostic tests have High Sp and variable sn to accurately identify a disease

• because we know they are symptomatic = want to ID disease

Imaging modalities in brain evaluation

Gold standard: Brain MRI with contrast

• evaluates soft tissues and grey-white brain matter well

• delineates characteristics of masses (fat, blood,fluids,etc.)

• provides IV contrast to highlight blood supply to mass and rule out other critical diagnostic options (infections, abnormality of small nerves)

Pros and cons of CT with contrast for brain evaluations

• Pros: reasonable soft tissues, good bone and calcifications, fast

• Cons: long scan time, availability of machines, metal implants/pacemakers, not so great with calcifications

Principle cognitive biases in screening

• overdetection bias

• lead time bias

• length time bias

What is overdetection bias?

discovering a “disease” that may never actually become clinically significant for a patient

• overtreatment including life-stress

What is lead time bias?

detecting disease at a point earlier than it would otherwise be identified, causing prolonged appearance of survival time (no clinical benefit)

What is length time bias?

type of selection bias that states slower growing tumours have more chances to be detected than their rapidly growing counterparts, which cause symptoms before/between screening times

• ex: overestimate survival duration for slowly progressing asymptomatic cases vs poor prognosis for faster growing cases

Verdict on asymptomatic intracranial mass screening

• more evidence of benefit is needed to make a concrete decision

• it may be warranted for certain indications

  • ex: detecting NF1 in kids

• select population screening is likely valuable for patients with genetic conditions, prior cancers, or after radiation therapy to the head

Risk of breast cancer in women

• 85% of breast cancer cases occur without family history

• risk of breast cancer in women nearly doubles if there is a first-degree relative with breast cancer

• less than 15% of women diagnosed with breast cancer have a family member who is diagnosed with it

Controllable risk factors for breast cancer in women

• Combined hormone therapy

• dietary fat

• alcohol consumption

• lack of exercise

• smoking

• excess body weight

Uncontrollable risk factors for breast cancer in women

• genetic mutation

• chest wall radiation

• dense breast tissue

• ashkenazi ancestry

• family history

• previous atypical cells

• early menstruation

• late menopause

• no children

New alcohol guidelines for cancer risk

• more than two drinks a week is risky

• 3-6 drinks a week increases risk of developing cancers like colorectal and breast

• more than 7 drinks a week increases risk of heart disease and stroke

How do we screen for breast cancer?

• breast self-exam

• clinical breast exam

• 2D and 3D mammography

• handheld or ABUS ultrasounds

• MRI for high risk patients

• contrast-enhanced mammography

• molecular breast imaging

NOT THERMOGRAPHY

Optimal breast screening

• annual mammograms starting at 40 for average risk women and younger for high risk women

• continue mammograms after menopause as long as life expectancy is at least 7-10 years

• all women should be told their breast density

  • women with dense breasts should be encouraged to do BSE or supplemental screening

• ultrasound/MRI/contrast mammography

Mammography and mortality from breast cancer

• women having mammograms are 40% less likely to die from breast cancer

• 44% mortality reductions in women 40-49

Who needs additional screening?

• women at high risk (regardless of breast density) including women with breast cancer

• women at higher risk of interval cancer

  • those with dense breasts, genetic mutations, or cancer survivors

Myths about breast cancer

• only happens in middle-aged or older women

• all breast cancers can be detected on mammogram

• won’t get breast cancer if no family history

• always appears as a lump

• if a lump hurts, it’s not breast cancer

• compression of breast and radiation from mammograms can cause breast cancer

• breast density doesn’t change with age

• can’t get screened if you have breast implants