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DYNOtest Tg-pluS is a immunoradiometric assay (IRMA) for the quantitative determination of thyroglobulin in human serum. It is intended to aid in the monitoring for the presence of local or metastatic thyroid tissue in patients who have had thyroid gland ablation (by surgery with or without radioiodine therapy). DYNOtest Tg-pluS is also indicated for detecting the presence of thyroid tissue in patients with differentiated thyroid cancer when used with radioiodine whole body scans after recombinant thyrotropin (TSH) stimulation or thyroid hormone withdrawal. DYNOtest Tg-pluS includes a recovery test to aid in the detection of interfering anti-thyroglobulin antibodies or other substances.

DYNOtest Tg-pluS is a two-step immunoradiometric assay for the quantitative determination of thyroglobulin in human serum using a coated tube technique. Two antigen specific antibodies that recognize different binding sites on the antigen (thyroglobulin) are used in excess. In the first step, thyroglobulin in the sample, standard or control binds to rabbit anti-human Tg polyclonal antibodies attached to the solid phase. Following incubation, unbound thyroglobulin and serum components are washed from the tube. In the second step, the radioactive tracer (mouse antihuman thyroglobulin monoclonal antibody) reacts with the bound antigen forming a sandwich complex fixed to the side of the tube. Following a second incubation, unreacted tracer is washed from the tube and remaining radioactivity in the tubes is measured. The measured radioactivity is directly proportional to the quantity of thyroglobulin in the sample, standard or control. The standard curve is used to derive the thyroglobulin concentration in the patients samples.

Recovery Test: Because non-specific interferents and anti-thyroglobulin antibodies can result in falsely low thyroglobulin values, DYNOtest Tg-pluS includes a recovery test, the purpose of which is to aid in the detection of such interferences. In the recovery test, recovery buffer containing a known quantity of thyroglobulin, is added to the patient sample. In parallel, the recovery buffer is added to a recovery reference sample (thyroglobulin free serum). The patient sample, recovery sample and recovery reference sample are all run using DYNOtest Tg-pluS. The percentage recovery is determined by subtracting the patient Tg value from the patient recovery sample and dividing this result by the recovery reference Tg value:

Recovery Tg - Patient Tg x 100 = % Recovery Recovery reference Tg

Recovery values between 70% and 130% are considered valid. Values 130% are due to interferences; these patient results should be considered invalid.

Here's an analysis of the provided text, focusing on the acceptance criteria and the study used to evaluate the DYNOtest Tg-pluS device:

Acceptance Criteria and Device Performance for DYNOtest Tg-pluS

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state pre-defined acceptance criteria with specific threshold values for the clinical study. Instead, it presents the results of a clinical performance study and a comparison to a predicate device. The effective acceptance criteria can be inferred from the reported performance characteristics.

2. Sample Size and Data Provenance for the Test Set

• Sample Size for Test Set:
  • Clinical Performance Study: 133 patients diagnosed with thyroid cancer.
  • Predicate Device Comparison: 133 samples from patients diagnosed with thyroid cancer (likely the same cohort as the clinical performance study).
  • Interference from Tg auto-antibodies: 77 sera.
• Data Provenance: The clinical performance study was prospective in the sense that the device was evaluated on a specific set of categorized patients. The location of the test set is specified as occurring "at a single site," but the country of origin is not explicitly stated. Given the manufacturer is German (BRAHMS AG) and the distributor is US-based (BRAHMS Diagnostica LLC), it's possible the clinical site was in the US or Germany.

3. Number of Experts and Qualifications for Ground Truth

The document does not mention the number or qualifications of experts used to establish the ground truth for the test set.

4. Adjudication Method for the Test Set

The document does not describe a specific adjudication method (like 2+1 or 3+1). The "ground truth" (reference methodology) was established based on a combination of existing diagnostic results.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This study focuses on the performance of the in-vitro diagnostic (IVD) device itself, not on how human readers' performance might change with or without AI assistance. The device is an assay, not an AI imaging interpretation tool.

6. Standalone Performance Study

Yes, the studies reported are for the standalone performance of the DYNOtest Tg-pluS device. The clinical performance section, including sensitivity, specificity, PPV, and NPV, directly evaluates the algorithm/assay without human-in-the-loop performance modifications.

7. Type of Ground Truth Used

The ground truth for the clinical performance study was established using a combination of existing clinical diagnostic results and reference methods:

• "Tg results from a reference method (immunochemiluminescent method)"
• "results from radioiodine whole body scans following TSH stimulation by administration of recombinant TSH or withdrawal of thyroid hormone therapy."
• Patients were categorized into three groups: (1) free of thyroid tissue, (2) active metastatic disease, and (3) residual thyroid/thyroglossal duct remnants.

For the auto-antibody interference study, the ground truth was based on samples that "tested positive for Tg auto antibodies using a radioimmunometric assay (DYNOtest anti-TGn)."

8. Sample Size for the Training Set

The document does not specify a separate training set or its sample size. This type of in-vitro diagnostic assay (IRMA) typically relies on extensive analytical validation and calibration to established standards (like CRM 457, in this case) rather than a "training set" in the machine learning sense. The "standards" and "controls" mentioned in the device description are used for calibration and quality control, not for training a predictive algorithm in the same way an AI model would be trained.

9. How Ground Truth for the Training Set Was Established

Since a distinct "training set" in the context of machine learning is not mentioned or applicable to this type of assay, the concept of establishing ground truth for it is also not applicable here. The assay is calibrated against a standard (CRM 457), which serves as a known reference for target values.

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