Superscan in patients with nasopharyngeal carcinoma

Skeletal Metastases Presenting as Superscan on Technetium 99m Methylene Diphosphonate Whole Body Bone Scintigraphy in Different Type of Cancers: A 5-Year Retro-prospective Study

The purpose of the study is to find out the overall incidence of superscan among different type of cancers, causes of superscan and its relationship with other parameters such as age, sex, duration of disease, and serum alkaline phosphatase (ALP) levels. This was a retro-prospective study. Records of all previous bone scans and reported patients of superscan were re-evaluated retrospectively. Patients who were diagnosed as having superscan in the preceding 3 years with confirmed histopathological diagnosis were included in the retrospective group. In the prospective group, all the patients who were reported to have superscan appearance over the past 2 years of prospective period were included. Total of 6027 bone scans were examined in a 5-year period and out of which 80 cases were diagnosed as superscan. The overall incidence of superscan in different type of cancers was 1.3% (80/6027). Prostate cancer (46/80) was the most common cause of superscan appearance followed by breast cancer (10/80). Out of 6027 patients referred for bone scan, 307 patients had prostate cancer on histopathological examination. Out of 307 patients with prostate cancer, 46 had superscan appearance. Incidence of superscan in prostate cancer was 14.98% (46/307), and 71.73% (33/46) prostate cancer patients with superscan had Gleason score of 8 and above 8 with mean serum prostate-specific antigen level was 178.42 ng/ml in symptomatic patients and 122 ng/ml in asymptomatic patients. Out of all patients with superscan, 71 patients (88.7%) had elevated serum ALP levels. Overall incidence of superscan in our study was 1.3% in different type of cancer patients, and the most common cause of superscan appearance was prostate cancer. Incidence of superscan appearance in prostatic cancer patients was 14.98%.

Technical note: identifying the prostate cancer 'superscan' by quantitative skeletal scintigraphy

AIM

The risk of failing to recognize the false, normal pattern of the superscan is a real one, with potential consequences for diagnosis and treatment. Quantitative indices of bone activity have previously measured uptake ratios or exposure time. Such estimates from spot images have provided differentiation of the superscan from normal. More recent reports describe quantitative methods for scanning type gamma-cameras, relying upon significant computation, availability of image analysis programmes or the drawing of whole skeletal regions of interest. The aim of this study was to establish a set of reference values for the evaluation of skeletal scintigraphy images, using the whole-body count alone.

MATERIALS AND METHODS

Patients underwent a routine whole-body bone study using the scanning technique. The total counts acquired during the scan were used to compare the skeletal uptake of the radiopharmaceutical between prostate patients showing superscan image patterns (n=38), prostate cancer patients with normal scans (n=40) and a control group (n=40) with normal scans, referred for reasons other than prostate cancer.

RESULTS

Qualitative comparison showed patterns of avid bone uptake with diminished visualization of kidney and bladder activity in the superscan group, and normal scans in the control and prostate patient groups. Quantitation using total counts recorded directly from the whole-body bone scan showed a significantly raised value in the superscan group only (P<0.001). We have established a simple set of objective reference bands to complement visual interpretation of the scan.

CONCLUSION

The whole-body image count alone, with little or no additional processing, is a helpful discriminator for the nuclear medicine superscan. This may assist the identification of this relatively uncommon diffuse metastatic disease in men with prostate cancer and reduce the number of investigations that might otherwise be reported incorrectly as normal.

99mTc bone scintigraphy superscans: a review

Whole-body bone scintigraphy (bone scan) using a (99m)Tc-labelled pharmaceutical is one of the most commonly performed radionuclide examinations. In the normal patient, both the osseous components of the skeletal system as well as the kidneys and bladder are visualized. A superscan is defined as a bone scan which demonstrates markedly increased skeletal radioisotope uptake relative to soft tissues, in association with absent or faint genito-urinary tract activity. While a superscan is relatively uncommon, its recognition is important, as it is associated with a number of important underlying diseases. The purpose of this review article is to describe the causes and variable features of a superscan and depict patterns which may aid in defining the underlying cause for the scan. In addition, we will discuss other investigations that may help further to identify the underlying disease in such cases.