3OsteoporosisOsteoporosis is the most common metabolic bone disorder. It has been defined by the National Institutes of Health as an age-related disorder characterized by decreased bone mass and increased susceptibility to fractures in the absence of other recognizable causes of bone loss.
4OsteoporosisType 1. involutional osteoporosis affects mainly trabecular bone, occurs in women during the years after the menopause, and is related to a lack of estrogen. This is thought to account for wrist and vertebral crush fractures, which occur through areas of principally trabecular bone.Type 2. senile involutional osteoporosis. The fractures of old age seen at the hip, proximal humerus, pelvis and asymptomatic vertebral wedge fractures. This affects both trabecular and cortical bone and represents progressive loss of bone mass from the peak around the age of years.Secondary osteoporosis is due to an underlying medical condition, such as renal disease, malabsorption, or hormonal imbalance, or to medical treatment such as steroids or certain anticonvulsants
5Osteoporosis Risk factors Smoking Alcohol Poor diet Lack of exercise may be superimposed upon either involutional or secondary osteoporosis, including :SmokingAlcoholPoor dietLack of exerciseAn early menopauseStrong family historySmall frame
6OsteoporosisThe normal rate of bone loss is 2% per year, hence 20-40% of the female bone mass is already lost by the age of 65 years of age, beginning before the menopause and accelerating afterwards
7OsteoporosisOsteoporosis progression over 2Y UC Steroids 59F
8OsteoporosisBone mass is the major determinant of bone strength that can be measured by non-invasive techniques, and accounts for 75-85% of this parameter
9OsteoporosisBone densitometry is clinically indicated for the detection and assessment of osteoporosis and for the evaluation and monitoring of several diseases and therapies. These include:The detection of osteoporosis and assessment of its severity.Evaluation of perimenopausal women for the initiation of estrogen therapy.Evaluation of patients with metabolic diseases that affect the skeleton.Monitoring of treatment and evaluation of disease course.In addition it may be useful as an epidemiological tool and possibly in the future for screeningAmerican Society of Bone and Mineral Research
16DEXABecause photons of different energy are differentially attenuated by bone and soft-tissues, by measuring the percentage of each transmitted beam and then applying simple simultaneous equations, the absorption by bone alone and hence bone density can be calculated.This measurement is not a true density but rather an areal density, represented in gms/cm2
18DEXA DEXA has very high accuracy and precision (the difference in the measurement from a known standard)andprecision(observed deviation of serial measurements with time)both short and long termto within 1% at the hip and spine
19DEXA DEXA is at present the most precise measurement of BMD QCT is more sensitive to change
25Bone Densitometry DEXA spine check list Note the age, sex, ethnicity and weightDoes this match the reference ranges?Is the bottom of L4 roughly at the level of the iliac crestsAre there any ribs on L1ScoliosisAre the vertebrae correctly dividedAnything in the soft tissue
29Bone Densitometry DEXA spine check list Look for significant level to level variations15-20% difference between adjacent levels
30DEXA, what makes a good scan? 5-15 Lines of Iliac Crest. I recommend 1/2 of L5.5-10 Lines of T12.2 cm of tissue on both sides of the spine.Spine should be straight.No metal in spine.
31Common problems with spine scans. Spine isn’t straight.Scan starts in sacrum.Scan stops too soon.Wrong scan mode.Scan doesn’t include L5.
32What is a scan mode?This determines the speed the arm travels, and how much radiation the patient receives.The bigger the patient, the more radiation you’ll require.The smaller the patient, the less radiation you’ll require.
41DEXA Femur check list Hints for a good scan. Patient should be straight on table.Pack patient with rice bags.Shaft of femur should be straight.Rotate leg inward, this will hide the lesser trochanter.
42DEXA Femur check list Hints for a good scan. The Wards area is roughly half the neck areaTrochanteric area 8-14cm2 in women, 10-16cm2 in menCheck left and right and state side being used in report.
43nonIQ DPX scanning Show 15-30 scan lines prior to seeing ischium. There should be little or no lesser Trochanter.Straight shaft.25 lines or more above the Greater Trochanter.
58Bone DensitometryT score is compared to reference population, years, same sex, any race, any weight.Z score is matched for age, sex, weight and ethnicity.
59Two possible reasons for this lady’s Z score being worse than the T score?
60Two possible reasons for this lady’s Z score being worse than the T score?Obesity and race
61The T score is based on a white, same sex, age 20-40 population The T score is based on a white, same sex, age population. The patient's BMD is compared to this population's BMD. A lower T score means that the patient BMD is low compared to this young, healthy normal weight population The Z score compares the patient to an adjusted population, it adjusts for age, weight, and ethnic background. The Z score can be lower than the T score for the patient, if the average patient in this population has a higher BMD than the average in the T score population. This can be seen in patients with higher weights, (which increases bone density), and in African American groups, (which show increased bone density).If the patients comparison group has a generally higher bone density, then it is possible to have a poorer comparison to others of same age, than to younger comparisons in generally lower density group.
65Bone Densitometry Weight gain/loss and Z Weight gain (or loss) will not affect Z score comparison, since Z scores are weight matched, but should cause an increase (or decrease) in absolute BMD.An increase in weight, pushes up the reference range, and therefore the Z score may seem reduced, and vice versa.2.2lbs=1Kg
66Bone Densitometry Weight gain/loss and T Weight gain (or loss) should cause an increase (or decrease) in absolute BMD.Weight gain (or loss) will affect T score comparison, since reference range will not have changed.Hence an increase in weight with a corresponding increase in bone density, will look like a good improvement in T score, but fracture risk is unchanged.
70Bone Densitometry Comparison with previous Are the studies comparableAlways compare like with likeThornton L1-44th and Lewis (previously L2-4)Any intervening eventsCannot compare Hologic and Lunar
71Bone Densitometry Comparison with previous David Sartoris’s previous studies that do not mention the region or levels measured, were standardized for L1-4 and the femoral neck.He usually did not quote BMD.Many previous studies were prior to the current database.Use the percent young adult as a guide to percentage change.
72Bone Densitometry Comparison with previous If over a period of time there is an increase in BMD in the lower lumbar spine and decrease in the upper lumbar spine, it is likely there is OA of the lower facet joints, and the upper lumbar spine is a truer reflection of useful BMD.
73Bone Densitometry Comparison with previous Increase in BMD of the femoral neck can be due to calcar buttressing with OA of the hip.
74Bone Densitometry Comparison with previous If you want to eyeball the % for a comparison, use the young adult % since the reference range will not change with age.A static bone density is actually a good result over a significant period of timeIf a test is 1% precise, then a change has to be greater than 2% to be significant
75Bone Densitometry Comparison with previous If you would have expected the bone density to have fallen 4% in 2 years, and it is static, then this is a positive response to RX
76Bone Densitometry Comparison with previous Generally Rx affects all levels equally.OA does not.
82Bone mass in healthy children Radiology 1991;179:
83Bone mass in healthy children Increases with age, weight and pubertal Tanner stage.Tanner stage and weight are best predictors of bone mass.Age, sex, race, activity and diet are not good predictors, when weight and Tanner stage are controlled.Radiology 1991;179:
84Bone mass in healthy children Make sure we have at least the age and weight of the child, if not the Tanner stage.Radiology 1991;179:
101ReportBecause of the previous laminectomy at L4, which may also be affecting the reading on the inferior aspect of L3, the BMD is averaged at L1-2. Note is also made of mild decrease in the L4 vertebral height.163F
116ReportThe Z score is worse than the T score at all levels because the the Z score is compared to weight and ethnicity and African American females naturally have a higher bone density than the standard Caucasian used for the T score, even at the age of 47.1African American 47F
118New Case249F 2Y8M gap Lx spine up, Fem neck down
119ReportA common cause for the bone density of the lumbar spine to increase whilst that of the femoral neck decreases over time is, the development of lower lumbar spine end plate sclerosis and facet osteophytes.149F 2Y8M gap Lx spine up, Fem neck down
130ReportIt was noticed that the patient has had a recent barium study and that barium may therefore falsely elevate the bone density. A repeat study is therfore recommended.151F Barium in diverticulum from recent enema
134ReportAs the patient loses weight the T score worsens at a faster rate than the Z score because the reference range for the Z score also is lowered.However with the loss of weight the fracture risk does not increase as much as the T score worsens.16 yr later, 8Kg wt loss
200Bone Densitometry DEPA Gd153Accuracy similar to QCTLess radiation than QCTMeasures cortical and trabecularLess sensitive to early changesAffected by aortic Ca2+
201DPX-IQ scanning Show 25-40 scan lines prior to seeing ischium. There should be little or no lesser Trochanter.Straight shaft.25 lines or more above Greater Trochanter.
202Bone Densitometry QCT Single energy 97% accurate Dual energy not routinely available300mRFat content adversely affects accuracyDifficult to reproduce positioningCan only measure trabecular bone8X increase turnover of trabecular bone
204Non IQ has these versions Version 1.15 for the DPXalphaVersion 1.35 for the DPXLVersion 3.65 for the DPXVersion 1.15 for the DPXSFCan upgrade with the 3.65 u on all versions.
205DPXIQ versus DPXnonIQ Spine measure and analysis are the same. Scan modes vary depending on the type of DPX.Femur measuring is different.Femur analyzing is different.IQ and nonIQ are different animals.
206How is IQ different? IQ offers unlimited patients in database IQ offers Total Femur results, as well as Femoral Neck.IQ offers better resolution image.IQ offers automatic analysis of femurs.IQ offers better algorithms for femurs.
207How is nonIQ different? Limited patients in database (3500 to 7500). Offers only Femoral NeckResolution is not nearly as good.Must manually analyze all femurs.Algorithms not as good for femurs.