# Brain Metastasis Velocity (BMV) Calculator — Farris 2017

> Brain Metastasis Velocity (BMV) Calculator — Farris 2017 is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Computes Brain Metastasis Velocity (BMV) per Farris 2017, stratifying patients into low/intermediate/high risk categories after initial SRS failure

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/bmv
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/brain-metastasis-velocity-bmv-calculator-farris-2017-46ec6867
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_xNT3P0YgFcRqhL4ZcnMIB

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability brain-metastasis-velocity-bmv-calculator-farris-2017-46ec6867
```

Example prompt: Calculate the brain metastasis velocity for a patient who has had 8 new brain metastases in the 2.5 years since their first SRS — I need to know the BMV and whether that puts them in the low, intermediate, or high risk category per Farris 2017.

## When to prefer this

Use this endpoint when you need to apply the Farris 2017 Brain Metastasis Velocity formula specifically — particularly for NRG-BN009 protocol screening or post-SRS OS stratification. Prefer this over manual calculation when you need the exact BMV decimal and the low/intermediate/high risk band in a single call. Note: this endpoint does not count metastases from imaging — the caller must supply the count.

## Known failure modes

- new_brain_metastases outside range 0–200 returns validation error
- years_since_first_srs of 0 or negative returns error (must be >0.01)
- years_since_first_srs above 30 may be rejected
- missing required query parameters returns 400-level error
- payment failure (x402) if USDC not provided

## How this service works

Farris 2017 brain metastasis velocity: bmv = new_brain_metastases / years_since_first_srs, 1 decimal. new_brain_metastases integer 0-200; years_since_first_srs 0.01-30. Low if BMV <4 (median OS 12.4 months after initial distant brain failure), intermediate 4-13 (8.2), high >13 (4.3). Does not floor BMV (NRG-BN009). Not time since last SRS. magent does not count metastases on imaging. Not a diagnosis. Not a medical device.

## Output

Returns the calculated BMV value (new_brain_metastases divided by years_since_first_SRS, rounded to 1 decimal place) along with the risk stratum: low (<4, median OS ~12.4 months after initial distant brain failure), intermediate (4–13, median OS ~8.2 months), or high (>13, median OS ~4.3 months). Does not floor BMV. Not a diagnosis or medical device output.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "required": [
      "new_brain_metastases",
      "years_since_first_srs"
     ],
     "properties": {
      "new_brain_metastases": {
       "type": "integer",
       "description": "Cumulative number of new brain metastases since first SRS (integer 0-200). Caller-assigned; magent does not count metastases on imaging."
      },
      "years_since_first_srs": {
       "type": "number",
       "description": "Years since first SRS (0.01-30; must be > 0). Farris 2017 uses time since first SRS, not time since last SRS."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/brain-metastasis-velocity-bmv-calculator-farris-2017-46ec6867/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.magentlab.com](https://www.zero.xyz/host/api.magentlab.com/llms.txt)