Deck 1: imaging, surgery, path, chemo and rt

Question 1

Define the 2 properties defining quality of an image

Answer 1

1) Limiting spatial resolution= solve the spatial details of the underlying image
2) Signal to noise ratio. Ratio of the signal in a voxel/pixel to the variation signal found in its neighbours

Question 2

What are the site predispositions for canine pulmonary histiocytic sarcoma?

Answer 2

R middle and L cranial lung lobes

Question 3

What radiation wavelength are XR/CT and MRI

Answer 3

X-ray, electromagnetic radiation of extremely short wavelength and high frequency, with wavelengths ranging from about 10 x −8 to 10 x−12 metre. MRI much longer wavelength (uses radio waves)

Question 4

How often would the diagnosis change with 2 vs 3 view rads

Answer 4

12-15% and L + VD less sensitive than R and VD

Question 5

8 features of an aggressive bone lesion on x-ray

Answer 5

1) cortical lysis
2) Periosteal reaction: palisading, sunburst
3) Codmon triangle: evaluate periosteum and ossification
4) rarely crosses articular cartilage (OSA)
5) monostotic
6) May extend to periarticular soft tissue
7) long transition zone
8) loss of trabecular bone in metaphysis

Question 6

What is the agreement between x-ray and CT to determine mediastinal vs pulmonary origin of a thoracic mass

Answer 6

68% mediastinal, 63% lung

Question 7

What is the sensitivity of a) xray and b) echocardiography to diagnose a heart base mass?

Answer 7

XR- 50-70%, Echo 74%

Question 8

What are the Hounsfield units of the following structures:
Air
Soft tissue
Water
Fat
Bone

Answer 8

Air: -1000
Fat: -100
Water: 0
Soft tissue: 50
Bone 500-1000

Question 9

2 abdominal diseases better detected on CT vs U/S

Answer 9

ASAC metastases, insulinoma

Question 10

What is the size detection limit for pulmonary mets for Xray and CT

Answer 10

XR 6-7mm, CT 1mm

Question 11

At first CT staging what tumour is most likely to have pulmonary mets?

Answer 11

HSA

Question 12

In one study what percentage of ground glass nodules eventually become metastases

What criteria, in humans, suggest ground glass nodules are malignant?

Answer 12

Ground glass nodule= subsolid nodules that do not obscure underlying pulmonary structure. 75% eventually progress to metastases

Human criteria: >8mm, >22mm mixed lesion, mixed lesion with growth, pure ground glass progressing to mixed

Question 13

Criteria that could help to diagnose malignant over inflammatory pleural effusion on CT

Answer 13

Older animal, pleural thickening, more marked, thoracic wall involved, nodular diaphragmatic/pleural thickening, pulmonary mass

Question 14

2 imaging features to differentiate gastric lymphoma from other tumours

Answer 14

lower enhancement, large lymph nodes

Question 15

What radionucleotide is generally used for bone scintigraphy?

Answer 15

99m technitium methylene diphosphonate 99mTcMDP

Question 16

What are the scintigraphic features of thyroid carcinoma

Answer 16

heterogenous, extending outside margins, multifocal, large size, irregular margins

Question 17

List 4 radiopharmaceuticals used in PET/CT and their indications

Answer 17

1) 18FDG 18flurodeoxyglucose : most commonly used for cancer staging
2) Naf: sodium flouride: bone
3) FLT: deoxy18flurothymidine: proliferating tissues
4) CuATSM: hypoxia

Question 18

What is the percentage of non-diagnostic samples in CT guided pulmonary sampling? What is the accuracy and the complication rate?

Answer 18

% non diagnostic = 35% FNA, 20% biopsy
accuracy= 90% FNA, 80% biopsy
complications 43%- 1/3 bleeding, 1/3 pneumothorax, 1/3 both

Question 19

Explain the principle of PET/CT using 18FDG

Answer 19

Uptake is due to increased glucose transporter (GLUT1). FDG can be phosphorylated once inside active tissues but cannot be de-phosphorylated/cannot participate in glycolysis so accumulates. Trapped in metabolically cells- not just cancerous ones.

Question 20

What ultrasound finding is relatively specific for renal lymphoma in cats

Answer 20

subcapsular hypoechoic thickening of kidney

Question 21

What are 3 ultrasound techniques that can help identify tumour vascularisation

Answer 21

colour doppler, spectral doppler and contrast enhanced ultrasound

Question 22

How does ultrasound work?

Answer 22

A piezo-electric crystal generates very high frequency acoustic waves. The variation of acoustic impedence between tissues makes the signal/image

Question 23

What is the risk of major haemorrhage and the risk of clinical complication with liver biopsies in dogs and cats?

Answer 23

haemorrhage: 42% dogs, 56% cats

clinical 2-4% dogs, 17% cats

Question 24

What are the pros and cons of adrenal FNA?

Answer 24

Pros: good to differentiate adrenocortical from medullary tumours, safe (18% complication risk, 1 in 50 death) good diagnostic yield (70%)

Cons: unlikely to change next steps, 1/50 risk of death, bad for differentiating benign from malignant

Question 25

What are 2 CT criteria in favour of GIST over other mesenchymal intestinal tumours

Answer 25

caecum, peritoneal effusion

Question 26

What is the FLAIR sequence useful for?

Answer 26

Free flowing fluid (CSF) is dark but non free fluid (oedema) is bright. If there is oedema near a ventricle, FLAIR can highlight this.

Question 27

What is the typical MRI appearance of most tumours? What tumour can be the opposite?

Answer 27

T2 isointense to hyperintense, T1 iso to hypointense. Melanoma is the opposite- T2 hypointense, T1 hyperintense

Question 28

What structures are hyper/hypo intense on T2? What about T1?

Answer 28

T1 Hypointense: fluid (csf, oedema), blood (some), inflammation
T1 hyperintense: fat, protein rich fluid, blood (some)
T2 hypointense: protein rich fluid, tendon/bone/calcifications, blood (some)
T2 hyperintense: water (CSF, oedema), fat, areas of increased cellularity, blood (some)