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NUMBERS, BONE
NUMBERS, BONE
BONE
General:
--OSSEOUS NON-UNION 9mo is most conservative number, or 3 mo with no change.
--RADIATION.
MR edema up to 3 wks, increased fat in marrow by 1wk, complete by
6wks. Radiation osteitis onset: 8mo-4yrs. Post rad sarcoma: 4-30 yrs
mean 10yrs. Flaps may enhance
normally for 1.5 yrs.
--INDIRECT ARTHRO: exercise for more than 10 min. Imaging should be delayed when the traditional
indirect MR
arthrographic technique (as opposed to the biphasic technique) is used.
Delay time are 5–10 minutes in the wrist, elbow, or ankle; 15 minutes
in the shoulder and hip; and at least 30 minutes in
the knee. If there is hyperemia or synovitis of the structure of
interest, these times can be decreased by one-half.
Spine
--dens to posterior spinolaminar line (space allowed for cord, SAC at C1): <13mm predicts declining neurological fn
-- atlantodontal interval (anterior): >3mm abnormal in adults, >5mm poor prognosis
-- Endplate angulation at T12-L1 on lat xray >10deg abnormal http://www.ajronline.org/cgi/content/full/193/1/W33
Rest of Axial skeleton:
n Pectus
escavatum: Haller index (inner transverse rib cage distance/ inner
spine-sternum distance. Normal 2.0-3.0 (2.56 with SD .3) Over 3.2
start to consider surgery (eg Nuss procedure with bar)
Shoulder
AC joint >7mm adult men, 6mm women abnormal (plain films)
coracohumeral impingement likely if dist <6mm (CT or MR)
Elbow
Ulnar n (by MR) >8mm diameter abnml
Wrist/ hand
ulnar styloid fx: >2.4mm displacement non union likely
Union of scaphoid: distal scaphoid 6-8 wks, waist 8-12 wks, proximal 12-24wks
Arachnodactyly metacarpal index 8.8 male, 9.4 female
Pelvis/ hips
CE angle of Wiberg 21-25 borderline dysplasia, <20 dysplastic in men, 19 women (2sd). <18.5 is 2.5 SD below norm
Femoral head extrusion index: 86 ave, 73 2.5 SD below (14% stuck out ave, 27% definitely abnml)
symph pubis: >5mm too wide adult. 8.5mm child
alpha angle for femoroacetabular impingement: normal <55degrees
acet angle on axial CT: less than 15 impinges, greater than 60 subluxes
acet angle/ xrays: normal 27-51, mean 39
anteversion on axial CT (superimposing knee image to obtain true value): 12-39normal,
mean 23 (33 at birth). 35 normal at birth.
Ilioischial line- medial acetabular wall distance for dx of acetabular protrusio < or = 7mm in females, 3mm in males
Valgus hip on AP xray angle <135. Varus <120
Knees
-- CT or MR
patellarfemoral disloc numbers. Trochlear dysplasia if sulcal angle
>144 deg , <3mm depth of femoral trochlea is dysplastic <5mm
hypoplastic. <11deg inclination (line through lat facet
and posterior bicondylar line) is tilted patella. >20mm distance
from center of trochlea to tibial tubercle implies excessive
lateralization of tibial tubercle (15-20 indeterminate)
-- >2mm offset of patellar artic surface by fx means sx
Ankle/ feet
n >15 deg difference with stress = 2or more ligaments
torn.
n <3mm intermetatarsal bursa likely physiologic (MR).
n <5mm MOrtons' neuroma likely insignificant (MR).
n lateral impingement in PTT disfunction: ap ankle xray: angle of tibial long axis to medial cortex of calcaneus:
>6 abnml, >16 worse, >26 severe
- height of syndesmotic recess above ankle joint/ plafond:
no more than 12mm (above this, likely fluid from interosseous membrane tear)
Pediatric Foot Deformity
Hind foot:
Tibiocalcaneal angle: 50-90 degrees (Standing)
Talocalcaneal Angle: Lateral: 40 (25-55)
AP: (20-40)
Mid Foot (cavus or planus)
-lateral midtalar line should hit the
Hind foot:
Tibiocalcaneal angle: 50-90 degrees (Standing)
Talocalcaneal Angle: Lateral: 40 (25-55)
AP: (20-40)
Mid Foot (cavus or planus)
-lateral midtalar line should hit the
NUMBERS, NON-MSK
X-ray
ET best 5cm above
Aortic balloon best 2cm below top of arch
CT
Aorta, thoracic
Ascending aorta aneurysm >5.0cm
NORMAL LESS THAN
Aortic valve 2.6cm
Sinus of valsalva 4.0cm
Sinotubular junction 3.4cm
Descending 3.5cm 3.5-4.0 ectatic aneurysm >4.0
SURGERY INDICATED: ascending aorta 5.5 male, 5.0 female, descending 6.5, abd 5.0
GU
Kidney: hyperdense kidney cyst: non-contrast density >70 <3 cm in size, rounded smooth contours, no enhancement (on postcontrast).
Simple Cyst <10HU, simple appearing. If it looks simple but has higher HU (ie 17) look at the HU for the gallbladder or bladder, it might help your decision.
Simple Cyst <10HU, simple appearing. If it looks simple but has higher HU (ie 17) look at the HU for the gallbladder or bladder, it might help your decision.
Adrenal. Only 6 month f/u of nodule needed. http://www.ajronline.org/cgi/content/full/196/2/W109
Adrenal washout adrenal= adenoma (simple method without pre-con value used): 40%
Interstim bladder stimulator should be at S3
Neuro
cerebellar tonsillar ectopia 5mm below foramen magnum
Cranial Nerves MIDBRAIN (I-IV) PONS (V-VIII) MEDULLA (IX-XII)
(4P) (7,8 lateral) (9,10 lateral)
Cranial Nerves MIDBRAIN (I-IV) PONS (V-VIII) MEDULLA (IX-XII)
(4P) (7,8 lateral) (9,10 lateral)
cardiac
Normal width of RV wall <6mm
Chest
non-solid
nodules (ground glass opacity GGO (Rad dec 09 Naidich) <5mm ignore,
5-10mm follow, >1.0 cm follow for 3 months then consider surgery.
For mixed solid/ GGO: more aggressive
Thymus: convex outer margin after teens abnormal. 18mm thick <20yo, <13mm>20yo
GI
n gastric banding. Phi angle 4-58deg. Pouch 4cm
or less. Lumen of band 3-4mm. Should empty pouch in 15-20 min. Band about 5cm below diaphragm.
n -- fatty liver Suggest if less dense than spleen,
(iff less than 0.8 spleen 100% specificity). NECT <48HU likely fatty, <40HU definite (30% fat)
Vascular
gonadal vein: >8mm abnormal
splenic art >2cm may operate
ULTRASOUND
OB
n See
yolk sac 5.5 wks, fetal pole 6 wks normally
n Blighted
ovum/ anembryonic pregnancy. Transvaginal imaging: >10mm mean sac
diam without yolk sac, >18 without fetal pole. Transabdominal:
>20mm without yolk sac, >25mm without fetal pole
--HCG threshold where should see sac in transabdominal scan: 3600, transvaginal
3000
--length of cervix <30wks gestation: normal 35-40mm. Less than 2.5cm indicates
incompetent cervix.
--C-section scar <5mm thick endometrium report, <3mm concerning
--nuchal fold >6mm abnormal (nuchal has 6 letters!)
--Praevia <2cm from os. Re-scan at 28 wks.
-- <70 BPM cardiac definite problem <100 concerning
-->6mm yolk sac bad
-- amnion should not be visible until 7 wks, disappears again at 12 wks. If visible
< 6wks is abnormal
Gyn
Endometrial stripe Postmenopausal <5mm OK. Pre-menopausal >16 concerning.
Ovaries cyst: pre-menopausal: >5.0 cm simple cyst: f/u scans within 10 days after
a menstrual period
post-menpausal: <1.0cm no f/u, 1cm-5cm follow, >5cm remove
Abd-Pelvis
TIPS 90-190cm/ sec IN stent. >50 change WITHIN stent abnormal. Portal vein <30cm/ sec
abnormal, hepatic vein <40cm
<7mm portal vein: suspect NO portal vein (cavernous transformation),>13 mm suspect portal HT
Renal artery stenosis: >3x aortic velocity or >200cm/ sec is stenosis.
SMA >275cm/sec systolic is 70% stenosis
Celiac >200cm/ sec is 70% stenosis
Nutcracker left renal vein >100cm/ sec at stenosis significant or 5 times velocity of upstream vein
transplant kidney: 250cc/sec, 3.5 ratio to iliac art
Bladder emptying fraction by US <35% abnormal
AAA 1.5 times size of adjacent aorta
Pancreatic
cysts less than 3cm usually benign, can follow q6mo x 2, then yearly out
to 3 years. Assuming no bad features! (eg, eggshell calcif = mucinous
tumor)
Peds
US of inperforate anus ,<10mm LOW skin to rectal pouch: LOW, 10-15mm gray zone , >15mm HIGH
DDH hip: alpha angle on coronal image >60 normal, 50-59 follow, <43 treat
Carotids
Carotid arteries 230cm/ sec >70% stenosis, >4.0 ratio to CCA
AV Fisulas renal pts
peak sys velocity: arterial 100cm/sec-400cm/sec normal, venous 30cm/sec-100cm/sec normal
Lower extremity arterial
Normal velocities CFA 100cm/ sec, popliteal 70 , peroneal 40-56cm/ sec
MR
Body
adenomyosis transitional zone: <8mm normal, 8-12 gray zone, >12 diagnostic
FLUORO
n Gastric band phi angle on scout: 4-58 deg normal,
4-5cm below diaphragm, 3-4mm stoma
n Peds cystogram: Bladder capacity: age plus 2 times
30
Anorectal angle defecogram: conservative rest numbers: 64-134, better 108-127.
Rest male 64-124, female70-134
Squeeze male 45-116 female 54-95
Strain male 67-128 female 75-128
---Defecography: rectocele less than 2cm deep not important. >10% retention post evac significant.
n <1cm Crohns stricture: capsule endoscopy contraindicated.
MISC
Contrast extrav: Get surgery consult if >60cc in normal space, 100 in large
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