Ultrasound Data Book (RTABF42 Cohort Exam 4)
ARIC Data Book
Cohort, Exam 4
Ultrasound data
Reader Trend Adjusted Derived Variables for Far Wall Thickness
Because of method drift over the visit and systematic differences between readers, an additional set of far wall thickness variables was derived to adjust for these problems. These are the Reader Trend Adjusted (RTA) variables for the far wall thickness (ie boundaries 4 and 5) as illustrated in the schematic in Appendix A. The following variables appear in the RTA data files.
| Variable Name | Description |
|---|---|
| id | Aric subject id |
| lbidrt45 | Imputed RTA far wall thickness, LBID |
| lbidwt45 | Weight for lbidrt45 |
| lindrt45 | Imputed RTA far wall thickness, LIND |
| lindwt45 | Weight for lindrt45 |
| lopdrt45 | Imputed RTA far wall thickness, LOPD |
| lopdwt45 | weight for lopdrt45 |
| mnd45_1 | Mean of the *rt45 variables |
| rbidrt45 | Imputed RTA far wall thickness, RBID |
| rbidwt45 | Weight for rbidrt45 variables |
| rindrt45 | Imputed RTA far wall thickness, RIND |
| rindwt45 | Weight for rindrt45 variables |
| ropdrt45 | Imputed RTA far wall thickness, ROPD |
| ropdwt45 | Weight for ropdrt45 |
Data Set Names
The data sets containing these variables are: rtabf41, rtabm41, rtawf41, and rtawm41 where rta indicates the variables are reader trend adjusted, the next two letters indicate the gender-race group, the 4 indicates it is a Visit 4 data set, and the 1 is a placeholder for the version of the data set.
ARIC Data Book
Cohort, Exam 4
Appendix A
B-Mode Derived Variable Site Prefixes
| LBI | Left Bifurcation |
| RBI | Right Bifurcation |
| LIN | Left Internal Carotid |
| RIN | Right Internal Carotid |
| LOP | Left Common Carotid: Optimal Angle |
| ROP | Right Common Carotid: Optimal Angle |
| QCC1 | First QC Repeat Scan (refer to QC01 for site identification) |
| QCC2 | Second QC Repeat Scan (refer to QC02 for site identification) |
Interfaces:
- Boundary between the periadventitia and adventitia of the near wall (not measured)
- Boundary between the adventitia and media of the near wall
- Boundary between the intima of the near wall and the blood
- Boundary between blood and intima of the far wall
- Boundary between media and adventitia of the far wall
- Boundary between adventitia and periadventitia of the far wall (not measured)
Max 23 = B-A; Max 45 = D-C; Min 34 = H-G
The extracranial carotid system is divided into one-centimeter segments: I = internal carotid; II = carotid bifurcation; III = common carotid. A maximum of eleven measurements is made by URC readers on each arterial wall interface, in each arterial segment. These measurements are placed equidistant at 1 millimeter intervals, represented by the eleven points placed on interface B2 on the internal carotid. Also shown on this schematic is the definition of a maximum and a minimum wall thickness variable. Computational formulae for these variables are shown in this appendix.
ARIC Data Book
Cohort, Exam 4
Ultrasound data
Reader trend adjusted derived variables for far wall thickness - black female
| LBIDRT45 | Imputed RTA far wall thickness, LBID | |
|---|---|---|
| N | Value | Description |
| 776 | Range | 0.277899 - 3.30014 ( median=0.865787 mean=0.9135704 std=0.2974449 ) |
| LBIDWT45 | Weight For LBIDRT45 | |
|---|---|---|
| N | Value | Description |
| 130 | 0.1666666667 | |
| 144 | 0.3333333333 | |
| 101 | 0.5 | |
| 53 | 0.6666666667 | |
| 16 | 0.8333333333 | |
| 332 | 1 | |
| LINDRT45 | Imputed RTA far wall thickness, LIND | |
|---|---|---|
| N | Value | Description |
| 776 | Range | 0.31087 - 3.45656 ( median=0.662641 mean=0.7051907 std=0.2587519 ) |
| LINDWT45 | Weight For LINDRT45 | |
|---|---|---|
| N | Value | Description |
| 131 | 0.1666666667 | |
| 146 | 0.3333333333 | |
| 128 | 0.5 | |
| 88 | 0.6666666667 | |
| 31 | 0.8333333333 | |
| 252 | 1 | |
| LOPDRT45 | Imputed RTA far wall thickness, LOPD | |
|---|---|---|
| N | Value | Description |
| 776 | Range | 0.401285 - 1.47565 ( median=0.725472 mean=0.7462038 std=0.1471238 ) |
| LOPDWT45 | Weight For LOPDRT45 | |
|---|---|---|
| N | Value | Description |
| 87 | 0.1666666667 | |
| 53 | 0.3333333333 | |
| 27 | 0.5 | |
| 8 | 0.6666666667 | |
| 2 | 0.8333333333 | |
| 599 | 1 | |
| MND45_1 | Mean Of The RT45 Variables | |
|---|---|---|
| N | Value | Description |
| 776 | Range | 0.461762 - 2.971815 ( median=0.784984 mean=0.8265835 std=0.2149949 ) |
| RBIDRT45 | Imputed RTA far wall thickness, RBID | |
|---|---|---|
| N | Value | Description |
| 776 | Range | 0.252492 - 4.24546 ( median=0.96781 mean=1.041641 std=0.393243 ) |
| RBIDWT45 | Weight For RBIDRT45 | |
|---|---|---|
| N | Value | Description |
| 131 | 0.1666666667 | |
| 131 | 0.3333333333 | |
| 94 | 0.5 | |
| 63 | 0.6666666667 | |
| 19 | 0.8333333333 | |
| 338 | 1 | |
| RINDRT45 | Imputed RTA far wall thickness, RIND | |
|---|---|---|
| N | Value | Description |
| 776 | Range | 0.164498 - 6.49485 ( median=0.674173 mean=0.7442480 std=0.4015394 ) |
| RINDWT45 | Weight For RINDRT45 | |
|---|---|---|
| N | Value | Description |
| 131 | 0.1666666667 | |
| 142 | 0.3333333333 | |
| 127 | 0.5 | |
| 92 | 0.6666666667 | |
| 34 | 0.8333333333 | |
| 250 | 1 | |
| ROPDRT45 | Imputed RTA far wall thickness, ROPD | |
|---|---|---|
| N | Value | Description |
| 776 | Range | 0.43805 - 1.99114 ( median=0.785206 mean=0.8086476 std=0.1716672 ) |