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.

[Bilateral deep vein thrombosis as presenting symptom of malignancy].

In 1865 Trousseau first described the association between venous thrombosis and malignancy. We now know that unprovoked deep vein thrombosis of the legs precedes the diagnosis of malignancy in more than 7% of the cases. In bilateral deep vein thrombosis the risk of occult malignancy exceeds 40%. We describe a patient with bilateral deep vein thrombosis as presenting symptom of pancreatic cancer.

The role of indirect radionuclide cystography during the acute phase of pyelonephritis in young women.

OBJECTIVE: To review our experience using dynamic 99mTc-diethylenetriamine penta-acetic acid renal scintigraphy combined with indirect radionuclide cystography (IRC) in the acute phase of pyelonephritis, as a possible alternative to the conventional imaging, as investigating acute pyelonephritis usually includes imaging the upper urinary tract during the acute phase, to exclude obstruction, and delayed voiding cysto-urethrography (VCUG) when underlying vesico-ureteric reflux (VUR) is suspected. PATIENTS AND METHODS: Between 1997 and 1999, 47 young women (median age 22 years, range 18-37) were hospitalized for acute pyelonephritis. The combined study was used during the acute phase of the disease, usually within 24 h of hospitalization. The principle of IRC is based on the reappearance of radioactivity in the ureters or kidneys after previously detecting renal clearance of an intravenously injected radioisotope. The increase in radioactivity over the ureters or kidneys indicates VUR. The subsequent follow-up included VCUG, after recovery and at least 6 weeks after discharge. RESULTS: Overall, 47 patients had early IRC studies; obstruction of the urinary tract during the acute phase of the disease was excluded in all. In 13 (28%) of the patients early IRC studies showed VUR involving 21 upper tract units. The renal parenchymal scan was impaired in 17 (36%) patients, and six of these 17 also had detectable concomitant reflux on IRC. Overall, 24 IRC studies (51%) were considered positive, showing VUR, renal parenchymal pathology or both; 23 (49%) were normal. Follow-up VCUG was used in 32 patients (68%); only three (9%) detected VUR. All of the patients with VUR on follow-up VCUG had also had an abnormal early IRC study, showing either reflux (two) or findings suggestive of pathological renal parenchyma (one). CONCLUSIONS: In addition to the well-established role of renal scintigraphy in excluding obstruction of the collecting system, early IRC is characterized by high sensitivity and accurate negative predictive value for detecting VUR. It can therefore be used to screen adults presenting with acute pyelonephritis for the presence of VUR. Patients with an abnormal IRC require follow-up VCUG after complete recovery, while those with a negative study may be managed expectantly, with no further radiological evaluation. This proposed strategy may avoid up to half of the delayed VCUG studies, preclude the related inconvenience, and substantially reduce the costs.

Lymphoscintigraphy for sentinel node mapping using a hybrid SPECT/CT system.

UNLABELLED: Lymphoscintigraphy is performed before sentinel node (SN) biopsy for SN mapping. It is of clinical importance mainly if the tumor is located in body parts with ambiguous lymph node drainage. The purpose of this study was to assess the clinical benefit of fused SPECT/CT images to planar images for SN mapping. METHODS: Thirty-four consecutive patients with cutaneous malignant melanoma (n = 28) and squamous cell carcinoma (n = 6) and scheduled for SN biopsy were enrolled. Primary tumors were located in the trunk (n = 12), in the extremities (n = 12), in the head and neck (n = 9), and in the penis (n = 1). Scintigraphy was performed using a hybrid gamma-camera/low-dose CT system. Planar images and fused SPECT/CT images were interpreted separately. RESULTS: SPECT/CT identified multiple draining basins in 6 of 12 patients (50%) with trunk melanoma and in 3 of 9 patients (33%) with head and neck melanoma or mucosal tumor. In 9 of 21 patients (43%) with a primary tumor located in the head and neck or trunk region, SPECT/CT-fused images identified SNs that were missed on planar images, 2 of which were involved with tumor. Three of the 9 nodes were located close to the injection site and were hidden by its scattered radiation, and 2 were in-transit nodes. Another 4 nodes, identified on fused images only, were located in an additional basin to those identified on planar images. Fused images were of no added value either in patients with limb melanoma or in a patient with a penile melanoma. CONCLUSION: SPECT/CT SN mapping provides additional data that are of clinical relevance to SN biopsy in patients with trunk or head and neck melanoma and in patients with mucosal head and neck tumor.

Engraftment and differentiation of human metanephroi into functional mature nephrons after transplantation into mice is accompanied by a profile of gene expression similar to normal human kidney development.

Metanephroi, the embryonic precursors of the adult kidney, can be induced in vivo to grow and develop. Despite their potential clinical utility for transplantation, the ability of human metanephroi to differentiate after transplantation into functional mature nephrons is mostly unknown. To address this, 70-d human metanephroi were transplanted into NOD/SCID mice; global gene expression patterns that underlie development of human metanephric transplants were analyzed and compared with normal human kidney development. In addition, functionality of the grafts was assessed by dimercaptosuccinic acid radioisotope scans at different times after transplantation. The results of hybridization to cDNA arrays when RNA was derived from normal human kidneys at 8, 12, 16, and 20 wk gestation demonstrated that a subset of 240 genes changed substantially with time. The induced genes can be classified as cell cycle regulators, transcription and growth factors, and signaling, transport, adhesion, and extracellular matrix molecules. Strikingly, clustering analysis of global gene expression at 2, 6, and 10 wk after metanephric transplantation revealed an expression profile that characterizes normal human kidney development. Moreover, maturation of the transplants was accompanied by an increased uptake of dimercaptosuccinic acid. Nevertheless, expression levels of specific genes were mostly found to be suppressed in the transplants compared with the normal kidneys. These data provide insights into human kidney development and support the possibility of the transplantability of human metanephroi. Understanding of the molecular regulation of the transplanted developing metanephroi might lead to the development of strategies aimed at increasing the levels of specific genes, nephron endowment, and graft function.