Endocrine NM Flashcards
Adrenal glands location
Retroperitoneum
Below diaphragm
Superior and medially to kidney
Between D12 and L1
Glomerular zone
Mineralcorticoid hormones
Aldosterone - - control BP
Fascicular zone
75% of cortex
Glucocorticoid
Cortisol - - glycemic control
Reticular zone
Androgens
Medulla
25% adrenal mass
From entoderm, chromaphine cells
Catecholamines
Adrenalin, noradrenalin
Degrade to metanephrines
Adrenal uptake
Analog of cholesterol (precursor of steroid hormones)
50% modulated by ACTH
30% by RAS
NP-59 protocol
I131-iodomethylnorcholesterol
1 mCi
II, IV, VII day image
High energy collimator
20-30 min, 500k-1mln counts
Photopeak 364 keV
NP-59 preparation
Thyroid block 3 days before
NP-59 uptake
Liver
Gallbladder
Colon (require laxative)
Add Tc-colloid - - taken up by liver - - subtraction - - adrenal visualization
NP-59 normal
Symmetric uptake of adrenal on II day
Right adrenal closer to liver - - scatter - - more active uptake
Scintadren
Se75-selenomethylnorcholesterol
0.16-0.22 mCi
Middle energy collimator
Cushing
Hypercortisolism - - image of cortex by NP-59
ACTH-dependent - - intense symmetric uptake in enlarged glands
Cortisol hypersecreting adenoma - - monolateral uptake, contralateral not visualized
Cortical nodular hyperplasia - - bilateral asymmetric uptake
Corticoadrenal CA - - lack of adrenal glands
Primary hyperaldosteronism
Conn sy
Corticoadrenal adenoma
Bilateral hyperplasia of glomerular zone
Carcinoma
Secondary hyperaldosteronism
Renin elevated
Arterial hypertension
Hypokalemia
Muscular disorders
ACTH suppression with dexamethasone
1-4 mg dexamethasone PO 7 days before and continue
Stop ACE inhibitor, spironolactone, diuretics
Cholesterol uptake in fascicular zone decreased
Good image of glomerular and reticular zone
DD adenoma vs bilateral hyperplasia
Image interpretation
Limitation
Indication
Normal - symmetric uptake 4-5 days after
Adrenal visualization before 4th day - - adenoma (unilateral) or hyperplasia (bilateral)
Not identify adenoma in case of hyperplasia
Primary hyperaldosteronism + normal CT
Adrenal incidentaloma
Benign adenoma - <3 cm, fat, <10 HU
Atypical - hemorrhage, no fat, necrosis, calcification, larger
>4 cm - malignant
>10 HU - - relative washout >40%, abs washout >60% (adenoma)
Adrenal MTS
Lung
Breast
Renal
Ovaries
GIT
Lymphoma
Melanoma
Adrenal medulla pathology
Pheo
Paraganglioma
MIBG
Guanethidine analog
WBS, SPECT 4h and 24h
Optimal for Pheo
Identify extra adrenal Pheo, MTS, post surgery recurrence
I131-MIBG
Image >24 h
False negative
I123-MIBG
Higher photon flux
Greater detection
Efficiency
Better spatial resolution
Lower radiation
Easier acquisition
Octreoscan = In111-pentetriotide
Somatostatin analog
WBS, SPECT 4h and 24h, >24h for uptake on abdomen
Less sensitive for adrenal lesions due to high physiologic kidney uptake
More sensitive for Paraganglioma of head and neck
More accurate in MTS
FDG
Not in protocol for Pheo
FDOPA
Analog of dopamine precursor
Same specificity as MIBG
Better spatial resolution
Greater signal-to-noise ratio
Esp Pheo of head and neck
Adrenal Ca genetic
Beckwith - Wiedeman - - in children
Li-Fraumeni - - mutation in p53 gene
MEN1 25-40%
Suspicious adrenal Ca
> 4 cm
Irregular margins
Central necrosis/haemorrhage
Enhancement
Invasion
Calcification
Adrenal Ca poor prognosis
> 50 years
Positive resection margins
N, M
Poorly diff
Functioning adrenal Ca
<5 cm
Female
Cushing
Female virilization or male feminization
Conn sy
Non-functioning adrenal Ca
> 10 cm
Male
Abd pain
Fullness
Palpable mass
Adrenal Ca image
CT - study of choice to dd benign vs malignant
FDG - limited uptake in adenoma, increased uptake in cancer
Most appropriate indication for Corticoadrenal scintigraphy
Cortisol hypersecreting adenoma
Suppression with dexamethasone
Stop ACTH stimulation - - reduce uptake in fascicular zone
For hyperaldosteronism and hyperandrogenism
Drugs interfere with MIBG
Tricyclic antidepressants
Antipsychotics
Beta blockers
Reserpine
Ca-channel blockers
Cocaine
Sympathomimetics
NP-59 + Tc-colloid subtraction
NP-59
Right adenoma
NP-59
Bilateral hyperplasia
MIBG
Pheo
Octreoscan
Paraganglioma