---
title: FHIR SR - Bone Mineral Density (BMD)
tags: fhir-project
---

<font color="red">FHIR</font> SR - Bone Mineral Density (BMD)
===

## Table of Contents
[TOC]

## 1. Introduction
 
This page is a sub-chapter of [FHIR Medical Imaging Structured](Reporthttps://hackmd.io/@victoriatjia/fhir-sr) which focus on define image finding form and diagnostic report template of bone mineral density (BMD) test.

A bone mineral density (BMD) test is a diagnostic test that measures the density of minerals, such as calcium, in the bones. The test is used to assess the strength and health of the bones, and to diagnose conditions such as osteoporosis and osteopenia.

A bone mineral density test is also referred to as dual energy X-ray absorptiometry (DXA). It’s an important test for osteoporosis, which is the most common type of bone disease. Osteoporosis causes your bone tissue to become thin and frail over time and leads to disabling fractures, and this often occurs on women and older adults.

**1.1 BMD Procedure**
For most BMD tests, you will be asked to lie on a table while an X-ray detector moves above your spine and hip. You may have one or both sides of your body scanned. The detector measures the amount of radiation in the form of X-rays, which are able to pass through your bone. The denser (stronger) your bones are, the less radiation will be able to pass through. The test takes about 5 to 20 minutes.

**1.2 T-Score VS Z-Score?**
The result of a BMD test is typically reported as a T-score and a Z-score.
* **T-score** is a comparison of the patient's BMD to the average BMD of a **healthy young adult of the same sex.**
* **Z-score** is a is a comparison of the patient's BMD to the average BMD of people of the **same age, sex, and ethnicity**.

**1.3. BMD Report Format**
Current BMD report format is different in every country. For example, in Taiwan BMD report specification is reference to [document](https://www.rsroc.org.tw/DB/Info/file/115-1.pdf) defined by Taiwan Radiological Society. In US, they reference to [document](https://iscd.org/wp-content/uploads/2020/11/us-adult-dxa-sample-report.pdf) defined by the International Society for Clinical Densitometry (ISCD). In this paper, we are going to propose an international standard specification document for BMD Report using FHIR Standard which we hope it can be the referenced for all of BMD Report for healthcare provider all over the world.

## 2. Goals
* Define internationalized BMD Structure Report specification in FHIR Standard

## 3. Methodology
### 3.1. Standard Terminology Used
* [LOINC](https://loinc.org/)
* [SNOMED-CT](https://www.snomed.org/)
* [MISAC defined Value Set](https://docs.google.com/spreadsheets/d/1FyR3ZWiG98h-vX52ByR_unxG0YgAFFtA78ceWFI24nA/edit?usp=sharing)

### 3.2. Report Structured

*Figure 1. Structured of FHIR BMD Report*

### 3.3. Report Specification
URL: https://docs.google.com/document/d/e/2PACX-1vQr-usXq5Z06u6wGx7Mhv6IQtZ3vSVZpPYjTmOSgiK0VWmpkbkGYPKIxEjKcLs0kQ/pub

### 3.4. Image Finding template
<!--
### Image Finding Result Template
**Technique**
* Baseline quantification of YY-year-old postmenopausal woman at Lumbar spine and Left and/or Right proximal femur and Left/Right forearm was performed using Manufacturer (GE-Lunar) model (iDXA), on YYYY -MM-DD (scan attached)

**Results:**
* The BMD at Lumbar spine: L1 0.000 g/cm2, L2 0.000 g/cm2, L3 0.000 g/cm2, L4 0.000 g/cm2, and the average BMD at L?-? is 0.000 g/cm2. The L? vertebra is excluded since there is more than a 1.0 T-score difference between the adjacent vertebrae / compression fracture etc.
* The BMD at left proximal femur: femoral neck 0.000 g/cm2 and total femur is 0.000 g/cm2.
* The BMD at Right proximal femur: femoral neck 0.000 g/cm2 and total femur is 0.000 g/cm2.
* The BMD at non-dominant (Right/Left) forearm is 0.000 g/cm2.
* Technical quality and limitations of the proximal femur study and forearm, stating why a specific site or ROI is invalid or not included.
* The lowest T-score is 0.0.
-->

#### 3.4.1. Bone Density Result Real-Case Example
##### 3.4.1.1. BMD Report Output (Front-end)
---
DXA BONE DENSITOMETRY
--
**NAME**: Jane
**DOB**: 10/02/1974
**REFERRING**: Dr. Adam Careful
**INDICATIONS**: Early menopause on estrogen levels. No period for 18 months
**PROCEDURE**: Dual energy x-ray absorptiometry (DEXA)
**BODY LOCATION**: Lumbar Spine

**BONE MINERAL DENSITY RESULT:**
| Scan Type | Region | Measured | Age | BMD (g/cm2) | T-Score |
|-|-|-|-|-|-|
| AP Spine | L1 | 17/06/2008 | 34.4 | 0.887 | -0.2|
| AP Spine | L2 | 17/06/2008 | 34.4 | 0.4 | -0.5|
| AP Spine | L1-L2 | 17/06/2008 | 34.4 | 1.148 |-0,4 |

**ASSESSMENT:**
The Spine L1-L2 BMD is normal.

**COMMENT:**
Osteopenia on measured BMD. The estimated 10-year probability of fracture based on present age, gender and measured BMD is less than 10%. This absolute fracture risk remains low. A follow-up assessment may be considered in 2 to 3 years to monitor the trend in BMD.

Thank you for your referral. Dr Henry Seven 17/06/2008

**NOTE:**
WHO classification of osteoporosis (WHO Technical Report Series 1994: 843)
- Normal: T-score equal to -1.0 s.d. or higher
- Osteopenia: T-score between -1.0 and -2.5 s.d.
- Osteoporosis: T-score equal to -2.5 s.d. or lower
- Severe/Established osteoporosis: Osteoporosis with one or more fragility fracture.

T-score: The number of s.d. from the mean BMD for a gender-matched young adult population.
Z-score: The number of s.d. from the mean BMD for an age-, weight- and gender-matched population.
GE LUNAR PRODIGY DENSITOMETER

---

##### 3.4.1.2. BMD Report in FHIR format (Back-end)
[**T-score value of Lumbar spine L1**](https://hapi.fhir.org/baseR4/Observation/7191492)
:::spoiler JSON example

{
  "resourceType": "Observation",
  "status": "final",
  "category": [ {
    "coding": [ {
      "system": "http://terminology.hl7.org/CodeSystem/observation-category",
      "code": "imaging",
      "display": "Imaging"
    } ]
  } ],
  "code": {
    "coding": [ {
      "system": "https://loinc.org/",
      "code": "38267-1",
      "display": "DXA Lumbar spine [T-score] Bone density"
    } ]
  },
  "subject": {
    "reference": "Patient/3de0818b-1f88ee30-575446ae-6a0320ee-699cc45b",
    "display": "Hannah Vlixie"
  },
  "encounter": {
    "reference": "Encounter/6947773"
  },
  "performer": [ {
    "reference": "Practitioner/example",
    "display": "Dr. Adam Careful"
  } ],
  "valueQuantity": {
    "value": 0.887,
    "unit": "g/cm²",
    "system": "http://unitsofmeasure.org",
    "code": "g/cm-2"
  },
  "bodySite": {
    "coding": [ {
      "system": "http://snomed.info/sct",
      "code": "lumbarSpine.vertebra1",
      "display": "Lumbar spine L1​"
    } ],
    "text": "Lumbar spine L1​"
  },
  "device": {
    "reference": "Device/6955456"
  }
}

:::

</br>

[**T-score value of Lumbar spine L2**](https://hapi.fhir.org/baseR4/Observation/7191495)
:::spoiler JSON example

{
  "resourceType": "Observation",
  "status": "final",
  "category": [ {
    "coding": [ {
      "system": "http://terminology.hl7.org/CodeSystem/observation-category",
      "code": "imaging",
      "display": "Imaging"
    } ]
  } ],
  "code": {
    "coding": [ {
      "system": "https://loinc.org/",
      "code": "38267-1",
      "display": "DXA Lumbar spine [T-score] Bone density"
    } ]
  },
  "subject": {
    "reference": "Patient/3de0818b-1f88ee30-575446ae-6a0320ee-699cc45b",
    "display": "Hannah Vlixie"
  },
  "encounter": {
    "reference": "Encounter/6947773"
  },
  "performer": [ {
    "reference": "Practitioner/example",
    "display": "Dr. Adam Careful"
  } ],
  "valueQuantity": {
    "value": 0.4,
    "unit": "g/cm²",
    "system": "http://unitsofmeasure.org",
    "code": "g/cm-2"
  },
  "bodySite": {
    "coding": [ {
      "system": "http://snomed.info/sct",
      "code": "lumbarSpine.vertebra2",
      "display": "Lumbar spine L2"
    } ],
    "text": "Lumbar spine L2"
  },
  "device": {
    "reference": "Device/6955456"
  }
}

:::
</br>

**Average T-score value of Lumbar spine L1 & L2**
:::spoiler JSON example

{
    "resourceType": "Observation",
    "id": "bmd",
    "status": "final",
    "category": [{
            "coding": [{
                    "system": "http://terminology.hl7.org/CodeSystem/observation-category",
                    "code": "imaging",
                    "display": "Imaging"
                }
            ]
        }
    ],
    "code": {
        "coding": [{
                "system": "https://misac-tcu.github.io/code-system/image-finding-type",
                "code": "dxa.bmd.tscore",
                "display": "DXA [T-score] Bone marrow density"
            },
            {
                "system": "https://loinc.org/",
                "code": "38267-1",
                "display": "DXA Lumbar spine [T-score] Bone density"
            }
        ]
    },
    "subject": {
        "reference": "Patient/2"
    },
    "performer": [{
            "reference": "Practitioner/example",
            "display": "Dr. Adam Careful"
        }
    ],
    "device": {
        "reference": "Device/6955456"
    },
    "encounter": {
        "reference": "Encounter/6947773"
    },
    "bodySite": {
        "coding": [{
                "system": "https://misac-tcu.github.io/code-system/body-site.html",
                "code": "lumbarSpine",
		"display": "lumbarSpine" 
            },
            {
                "system": "http://snomed.info/sct",
                "code": "122496007",
		"display": "Structure of lumbar vertebral column (body structure)" 
            }
        ],
        "text": "Lumbar spine"
    },
    "component": [{
            /*L1*/
            "code": {	
                "coding": [{
                        "system": "https://misac-tcu.github.io/code-system/body-site-location",
                        "code": "lumbarSpine.vertebra1",
                        "display": "Lumbar spine L1​"
                    },
                    {
                        "system": "http://snomed.info/sct",
                        "code": "66794005",
                        "display": "Bone structure of L1 (body structure)"
                    }
                ]
            },
            "valueQuantity": {
                "value": 0.887,
                "unit": "g/cm²",
                "system": "http://unitsofmeasure.org",
                "code": "g/cm-2"
            }
            /*END L1*/
        }, {
            /*L2*/
            "code": {
                "coding": [{
                        "system": "https://misac-tcu.github.io/code-system/body-site-location",
                        "code": "lumbarSpine.vertebra2",
                        "display": "Lumbar spine L2"
                    }
                ]
            },
            "valueQuantity": {
                "value": 0.4,
                "unit": "g/cm²",
                "system": "http://unitsofmeasure.org",
                "code": "g/cm-2"
            }
            /*END L2*/
        }
    ]
}

:::
<br>

**BMD Report**
:::spoiler JSON example

{
    "resourceType": "DiagnosticReport",
    "id": "dxa-bmd-report",
    "status": "final",
    "code": {
        "coding":  [
            {
                "system": "http://loinc.org",
                "code": "38269-7"
            }
        ],
        "text": "DXA BONE DENSITOMETRY"
    },
    "subject": {
        "reference": "Patient/2"
    },
    "effectiveDateTime": "2022-06-17",
    "issued": "2022-06-18T09:23:00+10:00",
    "performer":  [
        {
            "role": {
                "coding":  [
                    {
                        "system": "http://snomed.info/sct",
                        "code": "66862007",
                        "display": "Radiologist"
                    }
                ],
                "text": "Radiologist"
            },
            "actor": {
                "reference": "Practitioner/example",
                "display": "Dr. Adam Careful"
            }
        }
    ],
    "result":  [
        {
            "reference": "Observation/bmd"
        }
    ],
    "codedDiagnosis":  [
        {
            "coding":  [
                {
                    "system": "https://misac-tcu.github.io/code-system/diagnostic-result",
                    "code": "normal",
                    "display": "Normal"
                }
            ]
        }
    ]
}

:::

## References
* [MISAT WG2 Scenario 3 - BMD](https://mitw.dicom.org.tw/preconnectathon2.html)
* [Minimal requirement of DXA examination and report for 2016 - The Radiological Society Republic of China](https://www.rsroc.org.tw/papers/papers_detail.asp?id=115)
* [FHIR Observation BMD](https://build.fhir.org/observation-example-bmd.json.html)
* [Bone station](https://www.bonestation.com/resources.html)
* [Reading a DXA bone mineral density (BMD) study](https://www.youtube.com/watch?v=Ci8uUfGPSUs)
* [Guía de implementación Hoja Clínica](https://simplifier.net/guide/guadeimplementacinhojaclnica/ejemplodensitometria?version=current)
* [Fully automated bone mineral density assessment from low-dose chest CT](https://ui.adsabs.harvard.edu/abs/2018SPIE10575E..0ML/abstract)
* [Terminology format](https://blog.camel2243.com/2020/06/10/%E5%B8%B8%E8%A6%8B%E7%9A%84%E5%91%BD%E5%90%8D%E8%A6%8F%E5%89%87camel-case-snake-case-kebab-case/)
* [Camel Case vs. Snake Case vs. Pascal Case — Naming Conventions | Khalil Stemmler](https://khalilstemmler.com/blogs/camel-case-snake-case-pascal-case/#:~:text=Camel%20case%20(ex%3A%20camelCase),names%2C%20interfaces%2C%20and%20namespaces.)

What's Next?
* Create HTML report template for BMD
* FHIR Observation for BMD annotation
* Code system & value set format for body site, etc. -> opinion from radiologist
Format:
option 1: e.g. skull-base, kebab case (kebab = 烤串 = 串燒)
option 2: e.g. skull.base, property/attribute
option 3: e.g. skullBase, camel case (camel = 駱駝)
option 4: e.g. skull_base, snake case w/ underscore

:::info
**Q**: Which format is the most appropriate used as code-system item code?
**A** (Dr. Xu): Depends on each terminology
**Example 1: skull base**
skull is a noun(n.)
base is a noun
skull base is the base of the skull
of the skull, modifying base(noun), is an adjective(adj.), so here skull becoming adj.
so ==underscore(_) or period(.) might be appropriate, i.e. skull_base or skull.base==

**Example 2: iliac crest**
iliac is an adj.
crest is a noun
"iliac crest" is the "crest of the 'iliac bone'" (= 'ilium')
"iliac", modifying crest(noun), is an adj., meaning "of the ilium"
adj. has no property, so iliac.bone is inappropriate :face_with_raised_eyebrow:
and ==iliacBone might be somehow appropriate==
and iliacBone = ilium
ilium is not ileum: ilium is a bone, and ileum is a part of the small bowel

**Example 2: hyoid bone **
hyoid is an adj.
bone is a noun
==hyoidBone might be somehow appropriate==
:::

Coding system
* Background: Mass density in mammography and pi fu ke is different
* Create each value set for specific use-case
* BMD value set categorized based on body site， e.g. lumbra spine, arm,

![Uploading file..._xc25uw3zj]()

Find org yg tertarik develop gene & 影音 cloud