골밀도검사의올바른판독 분당서울대학교병원내분비내과김경민
Osteoporosis Osteoporosis is defined as a skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture. Normal bone Osteoporosis NIH Consensus Development Panel on Osteoporosis JAMA 285:785-95; 2001
Epidemiology of Osteoporosis in Korea Osteoporosis Fact Sheet in Korea (2014)
Epidemiology of Osteoporosis in Korea
Epidemiology of Osteoporosis in Korea
Osteoporotic Fractures
Bone content 120 trabecular cortical 100 80 60 75% 90% 40 20 0 10-33% 50%
Bone content Cortical Bone ( Compact bone) 80% of bone Harvesiansystem Harversian canal (nerve, vein, artery ) lacuna osteocyte Low bone turnover rate Trabecular Bone ( Cancellous, Spongy bone) 20% of bone, but 8 times higher metabolism than compact bone d/t larger bone surface Bone trabecula Fat, marrow content inter trabeculae
Life Time Risk of Osteoporotic Fractures Osteoporotic Fractures (50 세이상 ) Women (3/10) Men (1/10) Hip Fractures Women (9/100) Men(3/100) Spine Fractures Women (21/100) Men (7/100)
Bone Strength Bone Strength Bone Quality and Bone Mineral Density Architecture Turnover Rate Damage Accumulation Degree of Mineralization Properties of the Collagen/Mineral Matrix Sourced from NIH Consensus Development Panel on Osteoporosis. JAMA 2001;285:785-95
Bone Density & Age vs. Fracture Risk Age Ten Year Fracture Probability (%) 50 40 30 20 10 0 1.0 0.5 0.0-0.5-1.0-1.5-2.0-2.5-3.0-3.5-4.0 Femoral Neck T-score 80 70 60 50 Probability of first fracture of hip, distal forearm, proximal humerus, and symptomatic vertebral fracture in women of Malmö, Sweden. Adapted from Kanis JA et al. Osteoporosis Int. 2001;12:989-995.
중심골골밀도검사 말단골골밀도검사 정량적전산화단층촬영 이중에너지 X 선흡수계측법 정량적초음파
Bone Densitometry DXA pdxa QUS QCT pqct RA 골다공증의진단 (WHO 기준의적용 ) 가능 가능 ( 손목 ) 골절위험의예측가능가능가능가능가능 약물치료후치료반응확인 가능 가능 방사선노출약간적음 많음약간적음 비용보통싸다싸다비싸다보통싸다 Gold standard
? 1. 여성 65 세이상, 남성 70 세이상 2. 폐경후여성또는남성 50-69 세의남성으로골다공증의위험인 자가있는경우 3. 저체중, 저외상성골절, 위험약제복용등골절위험인자가있는 폐경이행여성 4. 50 세이상에서골절 5. 이차성골다공증의심 ( 예 : Pd 5mg 이상 /3 개월이상 ) 6. 골다공증의약물요법을시작하려는환자 7. 골다공증치료를받는모든환자의경과추적 8. 골감소의증거가뚜렷함에도불구하고치료를받지않는경우
T-score vs. Z-score T-score ( 환자의측정값 - 젊은집단의평균값 ) / 표준편차 (1SD) 골절에대한절대적인위험도를나타내기위해젊은연령층의골밀도와비교한값 -2.5 < T-score -1.0 ( 골감소증 ) T-score -2.5 ( 골다공증 ) T-score -2.5 + 골다공증골절 ( 심한골다공증 ) 50 세이상남성과폐경후여성 Z-score ( 환자의측정값 - 동일연령집단의평균값 ) / 표준편차 (1SD) 같은연령대의평균골밀도와비교한값 Z-score -2.0 ( 연령기대치이하 ) Below Expected Range of Age Within Expected Range of Age 이차성원인감별을위한검사 50 세이전남성과폐경전여성 이차성골다공증의유병률 ( 골다공증환자중 ) 남성 64% 폐경전또는폐경주변기여성 50% 폐경후여성 20-30%
WHO Bone Density Criteria: A Diagnostic Threshold Diagnostic Criteria* T-score: -1 Between 1- and -2.5-2.5-2.5 + fragility fracture Classification Normal Osteopenia(low bone mass) Osteoporosis Severe Osteoporosis The T-score indicates the number of standard deviations above or below the average peak bone density in young adults
Measurement of Lumbar Spine L1 에서 L4 까지의평균치를기준으로진단 압박골절, 퇴행성변화가있는부위를배제 L1 에서 L4 로가면서골밀도가증가하는데이런경향이역전되거나 T- 값이주위요추와 1 표준편차이상차이를나타내면퇴행성변화등판정에적합하지않은부위로제외하고판독 추적검사는반드시동일한관심영역 (region of interest, ROI) 을선택
Measurement of Lumbar Spine
Measurement of Hip Total hip, Femur neck 의수치를이용 Position: Femur 의장축이영상의세로축과수직이되어야한다. Femur neck 은영상의중심에위치해야한다. Lesser trochanter 가 보일까말까 한정도의 rotation 이되어야한다.
DXA Errors in - improper positioning - incorrect scan analysis - mistakes in interpretation - quality control Wrong clinical decision
Conditions causing overestimation of BMD Spinal degenerative and hyperostosis Vertebral fracture Extraoseus calcification ( lymph nodes, aortic calcification) Sclerotic metastasis Vertebral hemangioma Ankylosing spondylitis Overlying metal ( surgical rods/plates) Poor positioning of femoral neck(inadequate internal rotation) Excessive body weight Vertebroplasty/ kyphoplasty
Conditions causing underestimation of BMD Laminectomy Lytic metastasis Low body weight
Factors affecting BMD measurements Scoliosis Compression fractures Osteophytes, degenerative changes
Factors affecting BMD measurements Obesity Yu el al. J Bone Miner Res 2012 Jan;27(1):119-24 Aortic Calcification Smith et al. J Clin Densitom 1999 Summer;2(2):181-3
DXA 1 L3, L4 의퇴행성변화로 L1, L2 에비하여골밀도가높게측정되었다. L1 과 L2 의 T- 값평균치를이용하여골다공증으로진단할수있다.
DXA 2
Incorrect ROI F/75 2012 09 2013 09 L1-L4 가아닌 T12-L3 로 ROI 가설정됨 L1-L4 제대로설정
Incorrect ROI F/72 2012 10 2013 10 2012 년 hip 의 position 이잘못되어 ROI 가이상하게설정됨. 2013 년제대로측정 FN T -1.4 FN BMD 0.779 Bisphosphonate for 1yr FN T -2.1 FN BMD 0.695-11 %
측정오차와최소유의변화 (LSC, Least Significant Change) 측정오차 : 측정기 + 측정기사 (Measure 15 patients 3 times, or 30 patients 2 times) LSC = 2.77 x 측정오차 (95% 신뢰구간 ) 2.33 x 측정오차 (90% 신뢰구간 ) 1.84 x 측정오차 (85% 신뢰구간 ) 4.7% 측정오차 LSC 척추 1.9% 5.3% 대퇴골전체 1.8% 5.0% 대퇴경부 2.5% 6.9% 1.045 1.094 g/cm 2 The minimum acceptable precision for an individual technologist
Pitfall 골밀도검사전 1 주간의조용제사용유무확인 - 조영제가뼈나연부조직에흡수되어 DXA 의측정치에영향을줄수있음 당일핵의학검사여부확인 - 투여된방사선동위원소종류에따라뼈에섭취되는의약품있음 과거골밀도검사시행여부확인 - 재진환자의경우이전영상확인하여일관성있는검사시행 ( 환자자세, 관심영역의면적등 ) 내부및외부인공물분류하며외부인공물 ( 지퍼, 단추, 벨트등 ) 은검사전제거, 내부인공물 ( 장내가스, 조영제, 대동맥석회화등 ) 은제외하고분석
Assessment of Bone Quality Assessment of Bone Quality using DXA Bone Geometry TBS
Number of Fractures According to BMD Range T<-2.5 18% 2004 Arch Intern Med. Bone mineral density thresholds for pharmacological intervention to prevent fractures
Bone Strength Bone Strength Bone Quality and Bone Mineral Density Architecture Turnover Rate Damage Accumulation Degree of Mineralization Properties of the Collagen/Mineral Matrix Sourced from NIH Consensus Development Panel on Osteoporosis. JAMA 2001;285:785-95
BMD loss and Fracture Risk with Aging
Bone Quality Accessment using DXA Lumbar Spine Trabecular Bone Scoare Hip Femur Geometry
Bone Geometry Inner pelvis brim b a d c f e ac---hip Axis Length(HAL) bc--- Femoral Neck Axis Length(HAL) de--- Femoral Neck Width(FNW) f---neck Shaft Angle (NSA)
Hip Geometry Neck width Cross-sectional area Cortical Thickness
Lumbar Spine DXA Osteophyte 등의 Degenerative change 가노화에따라심화 Compression fractures 의발생
Trabecular Bone Score
Trabecular Bone Score
Take Home Message 골밀도검사의판독시, 올바른환자의 Position 정확한 ROI 의설정 ( 이전측정결과가있는경우이전측정 ROI 를비교한다 ) 올바른판독 ( 주변부의구조나, 나이골절력등을판단한다 ) Least Significant Changes 를확인 골밀도검사가환자의골절력을 100% 예측하지는못한다. 골밀도수치에비해, 반복적인골절환자의경우추가적인검사가필요함.