Predictive Value of Parathyroid Scintigraphy in the Preoperative Evaluation of Patients with Primary Hyperparathyroidism

Background and Aims:

The surgical gold standard in primary hyperparathyroidism was until recently exploration of all four parathyroid glands. Today more patients undergo minimal invasive procedures demanding more accurate preoperative localization studies. The aim of the study was to determine the positive predictive value (PPV) of parathyroid scintigraphy (PS) and to some extent ultrasonography (US), defined as the probability of finding one single adenoma on the affected side at surgery when the scans had shown one single focus.

Material and Methods:

Eighty-eight surgically treated patients (76 women and 12 men, 8 with multiglandular disease) were included. The PS consisted of 99mTc-sestamibi scan with dual-phase technique, both planar and SPECT imaging, followed by 99mTc-pertechnetate scan. A positive scan was defined as a single focus accumulating sestamibi. Focal lesions on US were defined as hypoechoic nodules.

Results:

PS was positive in 80 patients. Seventy-nine had only one focus, of which 64 were correctly localized adenomas (PPV 81%). Forty-seven of 77 US examinations were positive. In 44 there was only one focus of which 38 were correctly localized (PPV 86%). PPV was 97% when both examinations were positive.

Conclusions:

Both PS and US have acceptably high PPVs defined as the ability to predict whether or not one single focus represents a parathyroid adenoma. Concordant positive results were accompanied by a PPV close to 100%.

Combined DaT imaging and olfactory testing for differentiating parkinsonian disorders

OBJECTIVE

Dopamine transporter (DaT) imaging with single photon emission computed tomography (SPECT) detects loss of striatal dopaminergic innervation with very high sensitivity. It cannot readily distinguish idiopathic Parkinson's disease (iPD) and dementia with Lewy bodies (DLB) from atypical disorders (aPD). However, most iPD/DLB patients are hyposmic, whereas the majority of aPD patients were reported to have intact olfaction. For this reason, we conducted a longitudinal follow-up study to investigate the power of combined DaT imaging and olfactory testing to predict the final diagnosis of the patients.

MATERIALS AND METHODS

A total of 129 patients received [123I]FP-CIT SPECT and olfactory testing at baseline assessment. Clinical follow-up 30 ± 12 months later was the diagnostic standard of truth. A normative dataset of 24 healthy controls was used for comparison.

RESULTS

Baseline DaT imaging predicted a dopamine-deficient diagnosis with 98% sensitivity and 98% specificity. The combined DaT/olfactory testing correctly classified 91% of patients as iPD/DLB (PPV 91%). The PPV rose to 97% or greater in anosmic patients. In contrast, only 45% of aPD patients were categorised correctly by combined DaT/olfactory testing - mainly because of the presence of normosmic iPD patients.

CONCLUSIONS

In patients with an abnormal DaT SPECT, hyposmia yields an a posteriori likelihood of iPD/DLB of > 90%. In contrast, a finding of normosmia only increases the a posteriori likelihood of aPD to approximately the 50%.

Prognosis of adult-onset idiopathic bile acid malabsorption

BACKGROUND

From 1986 to 1993, 150 patients were investigated with the 75Se-homocholic acid taurine (SeHCAT) test as a late step in the investigation of chronic diarrhoea. On basis of low SeHCAT values and response to cholestyramine treatment, 33 patients were initially classified as having idiopathic bile acid malabsorption (IBAM). The aim was to describe the long-term clinical course of the disease and to assess the reliability of the SeHCAT test in diagnosing IBAM.

METHODS

The methods included 1) clinical follow-up with patient interview combined with information from medical records and 2) repeated SeHCAT test.

RESULTS

The diagnosis of IBAM had to be revised in three cases (inflammatory bowel disease in two patients, Clostridium difficile infection in one). Six patients were lost to follow-up and a further four patients were excluded from re-examination either because of old age (>80 years) or bowel resection, leaving 20 patients for re-examination, of which 16 completed both clinical follow-up and a new SeHCAT test. The median duration of symptoms before initial SeHCAT test was 2.5 (1-30) years. In 13 of 16 patients symptoms persisted, and SeHCAT values remained low and almost identical to the initial value after a median observation time of 88 (51-113) months. Despite initial response to treatment with cholestyramine, six patients had to discontinue treatment because of adverse effects or other compliance problems. In three patients the SeHCAT value showed a considerable increase, and bowel function had correspondingly normalized in these cases.

CONCLUSION

The study confirms the reliability of the SeHCAT test in diagnosing IBAM. Despite adult onset of symptoms, only a few patients improve after several years' observation. Treatment with cholestyramine is generally effective but not always tolerated.