Diagnostic Accuracy of 3T MR for Secondary Hyperparathyroidism Comparison With 4DCT
Condition: Parathyroid Gland Disease; Secondary Hyperparathyroidism
MeSH terms: Neoplasm Metastasis; Hyperparathyroidism; Hyperparathyroidism, Secondary; Parathyroid Diseases
Study type: Observational

Summary: 
      Secondary hyperparathyroidism (SHPT) is a common serious complication in the maintenance
      process of hemodialysis patients, characterized by diffuse or nodular hyperplasia of
      parathyroid glands. Parathyroidectomy for patients with drug-refractory SHPT is recommended
      in the clinical practice guidelines of the Global Organization for Improving Prognosis in
      Kidney Disease (KDIGO) and the Japanese Dialysis Therapy Society (JSDT) . Therefore, accurate
      localization and detection of parathyroid abnormalities is the key to avoid persistent
      recurrence of the disease. However, the sensitivity and specificity of the existing
      ultrasound and 99MTC-MIBI diagnosis are limited. CT examination is radiative and requires
      iodine contrast medium with nephrotoxicity, which may require timely dialysis and long-term
      monitoring for hemodialysis patients. 3T MRI has no radiation and does not need to use iodine
      contrast agent, which can well detect parathyroid lesions . Previous studies have reported
      that 3T MRI can diagnose primary hyperparathyroidism (PHPT), but the diagnostic efficacy of
      SHPT is still unclear. Therefore, this study aims to evaluate the preoperative diagnostic
      value of non-enhanced 3T MRI compared with 4DCT in patients with secondary
      hyperparathyroidism after hemodialysis.
    

Detailed description: 
      MR examinations were performed by using the 3 Tesla unit (Siemens Magnetom Verio, Siemens
      Medical Solutions) with a dedicated eight-channel neurovascular phased array coil. The field
      of view was adjusted to include the area from the angle of the mandible to the level of the
      tracheal carina. The protocol included an axial and a coronal T1-weighted fast spin-echo
      (FSE) sequence, an axial T2-weighted FSE sequence with Dixon fat saturation, and a coronal
      and sagittal T2-weighted FSE sequence with inversion recovery fat saturation.

      4DCT images were scanned with the 128-section dual-source multi-detector row unit (Somatom
      Definition Flash; Siemens Medical Solutions). All patients were scanned from the angle of the
      mandible to the carina. The 4DCT protocol included the acquisition of unenhanced images
      followed by the acquisition of arterial and delayed (venous) phase image series. Unenhanced
      images were obtained by using the following parameters: a collimation of 64×0.6 mm, 120 kVp
      for the deliverance of a dose-modulated amperage of 250 mAs, a pitch of 0.7, and a gantry
      rotation time of 0.28 seconds. The arterial and venous phase scans was performed in
      dual-energy mode with a dual source of 80 kVp and 140 kVp tube voltages using the following
      parameters: tube current-time product 230 and 89 mAs, respectively; collimation, 64 × 0.6 mm;
      rotation speed, 0.28 seconds; and helical pitch, 0.7. The arterial and venous phase scanning
      began automatically at 10 s and 35 s after the left common carotid artery reached the trigger
      attenuation threshold (100 HU) using automated scan-triggering software (CARE Bolus CT;
      Siemens Healthineers). The volume of iodinated contrast material (iohexol, Omnipaque 300; GE
      Healthcare, SH, China) was 70 mL, and the injection rate was 3 mL/s. The mean dual-source CT
      dose index volume was 34.5 mGy.

      The sensitivity and specificity as well as the positive-predictive and negative-predictive
      values (PPV, NPV) of each imaging modality for preoperative parathyroid hyperplasia
      localization to the correct quadrant were compared. For the per-quadrant localization, if a
      lesion was suspected to be parathyroid hyperplasia by the imaging report and was correlated
      with the surgical and pathology results, this was interpreted as a true-positive lesion.
      Otherwise, if the lesion was not confirmed to be parathyroid hyperplasia during surgery, this
      was considered to be a false-positive case. If a lesion was not reported by the radiologist
      in the exact quadrant but was present during surgery and histopathologic examination, this
      was regarded as a false-negative lesion.
    

Observational model: Case-Control
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Patients with severe SHPT who were receiving maintenance hemodialysis and had undergone
        parathyroidectomy were enrolled in the study.