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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 

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.  

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)    

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