Reducing the number of CTs performed to monitor personalized dosimetry during peptide receptor radionuclide therapy (PRRT)

Background

Peptide receptor radionuclide therapy (PRRT) with [¹⁷⁷Lu]-DOTA-TATE is an effective treatment of neuroendocrine tumors (NETs). After each cycle of treatment, patient dosimetry evaluates the radiation dose to the risk organs, kidneys, and bone marrow, the most radiosensitive tissues. Absorbed doses are calculated from the radioactivity in the blood and from single photon emission computed tomography (SPECT) images corrected by computed tomography (CT) acquired after each course of treatment. The aim of this work is to assess whether the dosimetry along all treatment cycles can be calculated using a single CT. We hypothesize that the absorbed doses to the risk organs calculated with a single CT will be accurate enough to correctly manage the patients, i.e., whether or not to continue PRRT.

Twenty-four patients diagnosed with metastatic NETs undergoing PRRT with [¹⁷⁷Lu]-DOTA-TATE were retrospectively included in this study. We compared radiation doses to the kidneys and bone marrow using two protocols. In the “classical” one, dosimetry is calculated based on a SPECT and a CT after each treatment cycle. In the new protocol, dosimetry is calculated based on a SPECT study after each cycle but with the first acquired CT for all cycles.

Results

The decision whether or not to stop PRRT because of unsafe absorbed dose to the risk organs would have been the same had the classical or the new protocol been used. The agreement between the cumulative doses to the kidneys and bone marrow obtained from the two protocols was excellent with Pearson’s correlation coefficients r = 0.95 and r = 0.99 (P < 0.0001) and mean relative differences of 5.30 ± 6.20% and 0.48 ± 4.88%, respectively.

Conclusions

Dosimetry calculations for a given patient can be done using a single CT registered to serial SPECTs. This new protocol reduces the need for a hybrid camera in the follow-up of patients receiving [¹⁷⁷Lu]-DOTA-TATE.

The association between Baker's cyst and medial meniscal tear in patients with symptomatic knee using ultrasonography

INTRODUCTION

There are nearly no studies about the association between Baker's cyst (BC) and medial meniscal tear (MMT) using ultrasonography.

PATIENTS AND METHODS

Nonselected patients who were referred for ultrasonography for the evaluation of knee pain were recruited. Demographic, clinical, and ultrasound parameters were documented.

RESULTS

One-hundred and nineteen patients were included and 131 knees were evaluated. There were 59 (~50%) female patients and mean age of 46.4±17.7 years. BC was found in 31 knees (23%). BC was significantly associated with MMT (P=.029) and age (P=.002) after adjusting for other covariates.

CONCLUSIONS

BC was strongly associated with MMT regardless of other intraarticular abnormalities.

Fahr's disease: bilateral symmetrical striopallidodentate calcification in two brothers with two distinct presentations

Bilateral striopallidodentate calcinosis, commonly known as Fahr's disease is a rare clinical entity present mainly with extrapyramidal signs and accompanied with metabolic, biochemical, neuroradiological and neuropsychiatric situations. It is characterised by the symmetrical and bilateral intracranial deposition of calcium associated with cell loss in the basal ganglia, cerebral cortex and cerebellum.In this study, we discussed two brothers' cases of Fahr's diseases who presented with different symptomatology. The first presented with walking difficulty, cramps and dysarthria and moderate memory impairment whereas the second with vertigo, ataxia, forgetfulness and headache. CT scans of both patients revealed intracranial diffuse bilateral calcifications in the basal ganglia and the cerebellum. The second patient revealed progressive cerebral atrophy but reduction in the calcification. Fahr's disease, although encountered rarely, should also be taken into account in the differential diagnosis of cases with abnormal intracranial calcifications along with other familial, congenital and metabolic diseases and syndromes.