#foarad

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A malignant bone process is more likely to be 1 or more metastasis than a primary bone cancer, and more bone mets are (osteo)lytic than osteoblastic (or sclerotic). Lytic bone lesions arise when tumor cells from a primary tumor in a different part of the body are deposited in the vascular beds of the bone matrix and grow with the help of parathyroid hormone-related peptide (PTHrP) stimulating osteoclasts to chew up existing bone. Sclerotic bone mets lead to more bone deposition through an uncertain mechanism. Both are seen better on CT or MRI than on plain xrays; sclerotic lesions are seen better than lytic ones on nuclear medicine scans (bone scintigraphy or PET-CT).

Pro-Tip: A single primary malignancy can lead to mixed lytic and sclerotic lesions.

Lytic lesion: Puyó Vera D, Renal cell carcinoma with metastases to the bony pelvis. Case study, Radiopaedia.org (Accessed on 20 Oct 2025) https://doi.org/10.53347/rID-29355

Sclerotic lesions: Niknejad M, Diffuse osteoblastic metastasis. Case study, Radiopaedia.org (Accessed on 20 Oct 2025) https://doi.org/10.53347/rID-84377

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Aerobic glycosis aka "the Warburg effect" is why PET imaging works: it tracks the abnormally high metabolism of glucose in ~80% cancers. Vander Heiden MG, Cantley LC, Thompson CB. Understanding the Warburg effect: the metabolic requirements of cell proliferation. Science. 2009 May 22;324(5930):1029-33. 

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Q. When should you order a follow-up chest x-ray after a child is treated for pneumonia? A. 4-8 weeks after completing antibiotics B. Only if the child has recurrent pneumonia C. Only if the child has empyema D. B and C. .

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A. The answer is D, order a follow-up CXR after 4-8 weeks only if a child has recurrent or complicated PNA. You want to make sure any radiographic findings have resolved and, if not, investigate a congenital abnormality such as pulmonary sequestration."

Image courtesy Dr. Ian Bickle, "Pleural Effusion," Radiopaedia. (This patient was a 65-year-old man who presented with acute shortness of breath.)

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Tools to calculate osteoporosis risk: FRAX (Fracture Risk Assessment Tool)

SCORE (Simple Calculated Osteoporosis Risk Estimation)

OSIRIS (Osteoporosis Index of Risk)

ORAI (Osteoporosis Risk Assessment Instrument)

The simplest is the OST (Osteoporosis Self-Assessment Tool), which uses weight and age and is available for both women and men.

Citation: Rubin et alia, "Comparison of different screening tools (FRAX®, OST, ORAI, OSIRIS, SCORE and age alone) to identify women with increased risk of fracture. A population-based prospective study," Bone 56:1 (Sept. 2013): 16-22.

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Q. What is the difference between a transient ischemic attack (TIA) and a cerebrovascular accident (CVA)?

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A. A transient ischemic attack--sometimes called "a baby stroke"--is when a clot forms in or travels to a small artery in the brain, temporarily blocking blood flow. A patient may or may not have symptoms such as slurred speech or loss of coordination. However, the body is able to clear the blockage and restore blood flow without the surrounding neurological tissue sustaining lasting damage that can be seen on a brain CT or MRI. 

A cerebrovascular accident occurs when the body cannot remove the blockage, causing permanent brain damage that can be seen on imaging. Sometimes with time and therapy a patient may recover some or all of the skills they lost, other times the damage is too severe. For instance, a stroke in the motor cortex that causes flaccid paralysis can, after 6 months, lead to spastic paralysis as the lower motor neurons degenerate from the lack of stimulation from the now-dead upper motor neurons.

Pro-Tip--We *used* to define a TIA as an incident in which symptoms resolved within 24 hours and didn't leave damage on CT or MRI imaging of the brain, but up to 50% of these did cause scarring. Now any event that causes scarring is defined as a stroke, no matter whether the patient had symptoms or how long they lasted.

Image: 80 y/o man who presented with left-sided hemiparesis; image is CT 3 days after stroke. Case contributed by Dr. Sajoscha Sorrentino, "Right MCA infarction," Radiopaedia, https://radiopaedia.org/cases/right-mca-infarction

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Q. Which infants should get a hip ultrasound* to evaluate for developmental dysplasia of the hip?

A. Those who are >6 weeks but <6 months of age with at least 1 risk factor: breech positioning at birth, family history, and/or instability on exam. Order the imaging for at least 6 weeks of age, to allow time for self correction or early defects. *There is limited evidence that infants 4-6 months should get AP hip xrays instead. By 4 months the femoral head is starting to ossify enough to be seen, however ultrasound can also evaluate the cartilage.

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Q. What pastry-themed finding in the pons can be seen on brain imaging in neurodegenerative disorders? .

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A. The "hot cross bun sign," a T2 hyperintensity that represents selective degeneration of the pontocerebellar tracts, can be seen in conditions such as  Multiple System Atrophy C (olivopontocerebellar atrophy). Case: 55-year-old woman presented with progressive difficulty in walking, urinary incontinence, abnormal behavior, mild cognitive impairment and sleep disturbances for 3 years duration. On examination Mini mental score was 26/30. Cerebellar ataxia was present with rebound phenomenon. Hypertonia was observed in both upper and lower limbs with brisk tendon reflexes and extensor plantar reflex. There was no significant muscle wasting. Case courtesy of Dr Aruna Pallewatte, Radiopaedia.org, rID: 39232. For more, see Professor Frank Gaillard, "Hot cross bun sign (pons)," Radiopaedia, https://radiopaedia.org/cases/5465/play?lang=us.

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Carotid Dopplers have an uncertain effect on death after stroke

VA clinical researchers recently published a large, prospective, observational cohort study that confirms 6 best practices for reducing odds of both 90-day and one-year mortality after a TIA or CVA. 

All patients should have carotid artery Dopplers within 14 days to measure stenosis that might require intervention via carotid endarterectomy (for symptomatic stenosis >70%, or asymptomatic stenosis >80%). Carotid artery imaging was associated with an adjusted odds ratio of 0.49 (95% CI, 0.38-0.63) for 90-day mortality and 0.61 (95% CI, 0.52-0.72) for 1-year mortality. 

The study results were confounded by the finding that patients with prior endarterectomy had better 90-day outcomes than those without. The authors speculated that surgeons had operated on patients who were healthier ("better surgical candidates"), thus the procedure itself may not have been not responsible for their survival but rather merely an indicator of their general well-being.

Bravata DM, Myers LJ, Reeves M, et al., "Processes of Care Associated With Risk of Mortality and Recurrent Stroke Among Patients With Transient Ischemic Attack and Nonsevere Ischemic Stroke," JAMA Netw Open. Published online July 03, 20192(7):e196716. doi:10.1001/jamanetworkopen.2019.6716.