MRI induced heating of pacemaker leads: effect of temperature probe positioning and pacemaker placement on lead tip heating and local SAR.

Abstract

The radio frequency field used in magnetic resonance imaging (MRI) procedures leads to temperature and local absorption rate (SAR) increase for patients with implanted pacemakers (PM). In this work a methodological approach for temperature and SAR measurements using fluoroptic probes is presented. Experimental measures show how the position of temperature probes affects the temperature and SAR value measured at the lead tip. The transversal contact between the active portion of the probe and the lead tip is the configuration associated with the highest values for temperature and SAR, whereas other configurations may lead to an underestimation close to 11% and 70% for temperature and SAR, respectively. In addition measurements were performed on a human-shaped phantom inside a real MRI system, in order to investigate the effect of the PM placement and of the lead geometry on heating and local SAR.

AI evidence extraction

Main findings

Experimental measurements indicated that temperature probe positioning affects measured lead-tip temperature and local SAR during MRI RF exposure. Transversal contact between the active portion of the fluoroptic probe and the lead tip produced the highest measured temperature and SAR; other configurations could underestimate temperature by ~11% and SAR by ~70%. Additional measurements in a human-shaped phantom in a real MRI system were performed to investigate effects of pacemaker placement and lead geometry on heating and local SAR.

Outcomes measured

• Lead tip temperature increase
• Local SAR at pacemaker lead tip
• Measurement error/underestimation due to temperature probe positioning
• Effect of pacemaker placement and lead geometry on heating/local SAR (phantom measurements)

Limitations

• Frequency, MRI sequence parameters, and exposure duration not reported in the abstract
• Quantitative heating/SAR values (absolute) not provided in the abstract
• Phantom-based measurements; human clinical outcomes not described
• Sample size and number of experimental repetitions not stated

Suggested hubs

• medical-imaging-mri (0.95)
  Study examines RF exposure during MRI and associated heating/local SAR around pacemaker leads.
• implanted-medical-devices (0.9)
  Focus on pacemaker lead tip heating and effects of device placement/geometry.

{
    "study_type": "engineering",
    "exposure": {
        "band": "RF",
        "source": "MRI",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "Lead tip temperature increase",
        "Local SAR at pacemaker lead tip",
        "Measurement error/underestimation due to temperature probe positioning",
        "Effect of pacemaker placement and lead geometry on heating/local SAR (phantom measurements)"
    ],
    "main_findings": "Experimental measurements indicated that temperature probe positioning affects measured lead-tip temperature and local SAR during MRI RF exposure. Transversal contact between the active portion of the fluoroptic probe and the lead tip produced the highest measured temperature and SAR; other configurations could underestimate temperature by ~11% and SAR by ~70%. Additional measurements in a human-shaped phantom in a real MRI system were performed to investigate effects of pacemaker placement and lead geometry on heating and local SAR.",
    "effect_direction": "harm",
    "limitations": [
        "Frequency, MRI sequence parameters, and exposure duration not reported in the abstract",
        "Quantitative heating/SAR values (absolute) not provided in the abstract",
        "Phantom-based measurements; human clinical outcomes not described",
        "Sample size and number of experimental repetitions not stated"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "MRI",
        "radiofrequency field",
        "pacemaker",
        "lead tip heating",
        "local SAR",
        "fluoroptic temperature probe",
        "probe positioning",
        "phantom"
    ],
    "suggested_hubs": [
        {
            "slug": "medical-imaging-mri",
            "weight": 0.9499999999999999555910790149937383830547332763671875,
            "reason": "Study examines RF exposure during MRI and associated heating/local SAR around pacemaker leads."
        },
        {
            "slug": "implanted-medical-devices",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Focus on pacemaker lead tip heating and effects of device placement/geometry."
        }
    ]
}

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