Quantitative lymphoscintigraphy of the lower limbs for the diagnosis of phlebolymphoedema.

INTRODUCTION: Phlebolymphoedema is caused by the interaction of the venous and lymphatic systems in a state of chronic venous insufficiency in which increased microvascular filtration causes an increased rate of lymph production. Lymphatic drainage rate increases in response, but this is unsustainable and can cause lymphatic failure and oedema. We hypothesise that in phlebolymphoedema we could measure unusually high lymphatic drainage while the lymph system is still fully functional. METHOD: Patients referred for lymphoscintigraphic investigation of swollen legs between April 2021 and December 2022 were reviewed. Quantitative lymphoscintigraphy was performed following the technique of Keramida et al . (2017) and ilio-inguinal nodal uptake (IIQ%) was calculated. The presence of scintigraphic features of increased lymph production was noted for each limb. RESULTS: A total of 39 patients were reviewed (78 limbs, 29F, 10M). Seven limbs were identified with supranormal lymphatic function (IIQ > 30%) plus three borderline. Of these 10 limbs, all had at least two scintigraphic features of increased lymph production. CONCLUSION: Quantitative lymphoscintigraphy, although developed for diagnosing abnormally low lymphatic function, may also have utility at the upper end of the spectrum for identifying chronic venous insufficiency. An IIQ% upper normal limit of 30% could be used to diagnose venous insufficiency as the cause for limb swelling. This is of note for patients of large body habitus in whom venous ultrasound is difficult.

Whole-body 75SeHCAT retention is determined by entero-hepatic bile acid recycling rate.

AIM: It has previously been proposed that entero-hepatic bile acid recycling frequency is a major determinant of whole-body retention (WBR) of SeHCAT. Hepatocyte to terminal ileum accounts for almost the entire cycle. The study aim was to test this hypothesis by comparing WBR with an estimate of speed of transit of bile acids using Tc-HIDA scintigraphy performed on a separate occasion. METHODS: Using an un-collimated gamma camera and patient-to-camera distance of 1.5 m, WBR at 7 days after oral SeHCAT administration was measured in 14 patients with chronic diarrhoea, of whom 10 had previous cholecystectomy. The distance reached within the intestine of Tc-HIDA at 1 h (n = 14) and 2 h (n = 7) following iv injection was graded as follows: grades 1 and 2: small bowel on left and right sides of abdomen, respectively; and grade 3: colon. Relationships between WBR and grade were assessed using Spearman rank correlation. RESULTS: Interval between studies ranged from 3 to 1219 (median 330) days. Grading correlated with WBR at 1 h (rs = -0.63; P = 0.02) and weakly at 2 h (rs = -0.68; P = 0.09) post-injection of Tc-HIDA. In nine patients in whom Tc-HIDA and SeHCAT scans were performed within 1 year of each other, the correlation remained significant at 1 h (rs = -0.73; P = 0.03). There was no difference in WBR or grading between patients with or without a gall bladder. CONCLUSION: Entero-hepatic bile acid recycling frequency is a major determinant of whole-body SeHCAT retention.

Absence of hepatic activity in lymphoscintigraphy performed with Tc-99m-Nanoscan.

INTRODUCTION: For assessment of lower extremity swelling using lymphoscintigraphy, several nuclear medicine departments in the UK have recently switched from Tc-Nanocoll to Tc-Nanoscan. The aim of the study was to compare quantitative and semiquantitative features of lymphoscintigraphy between these two tracers. METHODS: Twenty patients received Tc-Nanocoll and 20 received Tc-Nanoscan either side of the switch-over in our department. Tracers were compared with respect to visualisation of the liver, para-aortic lymph nodes and urine (all graded by consensus from 0 to 3; invisible-to-very prominent); and with respect to ilio-inguinal nodal quantification and ratio of liver-to-summed bilateral ilio-inguinal nodal activity at 120 min postinjection (L/N120). Scans were deemed abnormal when there was lymph diversion through skin or deep system, no activity in ilio-inguinal nodes at 60 min or negligible ilio-inguinal activity (<5%, left plus right) at 120 min. RESULTS: Liver was visualised in 18/20 Tc-Nanocoll but only 3/20 Tc-Nanoscan scans. Moreover, para-aortic activity was less prominent after Tc-Nanoscan. Urinary activity was more prominent after Tc-Nanocoll. There were 9/20 patients with stomach activity after Tc-Nanocoll compared with 1/20 after Tc-Nanoscan. Urinary and stomach activities correlated. There was an elevated L/N120, and therefore a suspicion of peripheral lympho-venous communication, in the single Tc-Nanoscan patient who displayed prominent hepatic activity. CONCLUSION: Hepatic activity is the result of accumulation of colloidal degradation products generated in lymph nodes, rather than intact colloid. Tc-Nanoscan gives less hepatic activity than Tc-Nanocoll because it is more resistant to intranodal degradation. Peripheral lymphovenous communication remains a possible alternative route for activity to reach the liver.

Correction to: Predictive and prognostic value of 18F-DOPA PET/CT in patients affected by recurrent medullary carcinoma of the thyroid.

The following affiliation should be added to the authors Agostino Chiaravalloti and Orazio Schillaci.

Predictive and prognostic value of 18F-DOPA PET/CT in patients affected by recurrent medullary carcinoma of the thyroid.

INTRODUCTION: Medullary thyroid carcinoma (MTC) is a malignancy accounting for about 5-8% of thyroid cancers. Serum calcitonin and carcinoembryonic antigen (CEA) levels are widely used to monitor disease progression. However, prognostic factors able to predict outcomes are highly desirable. We, therefore, aimed to assess the prognostic role of 18F-DOPA PET/CT in patients with recurrent MTC. MATERIALS AND METHODS: 60 patients (mean age 64 ± 13 years, range 44-82) with recurrent MTC were eligible from a multicenter database. All patients underwent a restaging 18F-DOPA PET/CT, performed at least 6 months after surgery. CEA/calcitonin levels, local recurrences, nodal involvement and metastases at PET/CT were recorded. SUVmax, SUVmean (also normalized to mediastinal uptake) and metabolic tumor volume were automatically calculated for each lesion, by placing a volume of interest around the lesion with 40% of peak activity as threshold for the automatic contouring. The patients were clinically and radiologically followed up for 21 ± 11 months. Rate of progression-free survival (PFS), disease-specific survival (DSS) and incremental prognostic value of 18F-DOPA PET/CT over conventional imaging modalities were assessed by Kaplan-Meier curves and Log-Rank test. Cox regression univariate and multivariate analyses were performed for assessing predictors of prognosis. RESULTS: 18F-DOPA PET/CT showed abnormal findings in 27 patients (45%) and resulted unremarkable in 33 (55%). PFS was significantly longer in patients with an unremarkable PET/CT scan (p = 0.018). Similarly, an unremarkable PET/CT study was associated with a significantly longer DSS (p = 0.04). 18F-DOPA PET/CT added prognostic value over other imaging modalities both for PFS and for DSS (p < 0.001 and p = 0.012, respectively). Neither semiquantitative PET parameters nor clinical or laboratory data were predictive of a worse PFS and DSS in patients with recurrent MTC. CONCLUSION: 18F-DOPA PET/CT scan has an important prognostic value in predicting disease progression and mortality rate.

Incidental Detection of Retiform Hemangioendothelioma by 68Ga DOTATOC PET/CT.

A 52-year-old man underwent Ga DOTATOC PET/CT scan for postsurgical staging of a neuroendocrine tumor of the lung. The PET images showed a single focus of increased activity in a soft tissue nodule located posteriorly to a cervical vertebra. Surgical removal of the lesion led to the histological diagnosis of retiform hemangioendothelioma.

Isolated Metachronous Splenic Metastasis From Colon Cancer Found by 18F-FDG PET/CT.

Isolated splenic metastases from solid malignancies are very rare. We report the case of a 58-year-old woman with isolated metachronous splenic metastasis from colon cancer detected 18 months after colectomy. F-FDG PET/CT allowed its recognition and guided the therapeutic approach toward surgery.

18F-FDG PET/CT in Metastatic Pilomatrix Carcinoma.

We describe the FDG PET/CT findings in an exceedingly rare case of metastatic pilomatrix carcinoma (PC). A 76-year-old man, who underwent incisional biopsy of a soft-tissue mass in the frontal scalp that revealed PC, was referred for an F-FDG PET/CT scan for staging purposes. PET/CT showed areas of increased radiotracer uptake corresponding to frontal mass and unsuspected lung lesions, which were later confirmed as metastases from PC at histological analysis. Clinical condition deteriorated rapidly, and the patient died 3 months after the initial diagnosis.

Breast Cancer Incidentally Detected by 18F-Choline PET/CT in a Patient With Recurrent Prostate Carcinoma.

A 79-year-old man underwent F-choline PET/CT for biochemical recurrence of prostate cancer. PET/CT images showed an area of elevated radiopharmaceutical uptake in a left pelvic node. In addition, a small focus of increased radiolabeled choline accumulation was seen in a small nodule of the right breast, which was later histologically characterized as an infiltrating ductal carcinoma. In this patient, choline PET/CT was critical in localizing prostate cancer recurrence and identifying a second unsuspected malignancy.

Active subcutaneous calcinosis demonstrated by fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography in a case of limited cutaneous systemic sclerosis.

Systemic sclerosis (SSc) is a rheumatic autoimmune disease of unknown origin causing fibrosis of the skin and the internal organs. The limited cutaneous variant is the most common subtype of SSc, and it is predominantly characterized by skin and soft-tissues involvement. A 72-year-old woman, who had been diagnosed with the limited cutaneous form of SSc 16 years before, underwent fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) examination due to unexplained weight loss and recent onset of fatigue and joint pain. PET/CT images showed widespread soft-tissue calcinosis characterized by elevated glucose uptake.

18F-FDG uptake in main arterial branches of patients with large vessel vasculitis: visual and semiquantitative analysis.

OBJECTIVE: Over the last decade, the contribution of (18)F-FDG (FDG) PET/CT imaging to the diagnosis of large vessel vasculitis has been widely investigated. The aim of this study was to evaluate a more extensive role for PET/CT in grading vascular inflammation in patients with different clinical stages of disease. METHODS: The images of 66 PET/CT studies of 34 patients, performed at diagnosis and/or during follow-up were reviewed. FDG uptake in different regions of aorta and in its major branches was visually (regional Score: rS) and semiquantitatively (regional SUVmean: rSUV) assessed. The global vascular uptake was also evaluated for each study by summing all rSs (summed Score; sS) and averaging rSUVs (averaged SUV; aSUV). FDG uptake in 15 PET/CT studies of control age-matched subjects without signs or symptoms of vasculitis was also analyzed. RESULTS: Higher levels of regional and global FDG uptake were found at diagnosis in comparison with follow-up studies of 12 patients with complete longitudinal observation (p value range 0.0552-0.0026). In the latter group high values were generally observed when disease relapse or incomplete response to therapy (active disease) occurred, whereas lower uptake was found in studies of remitted patients (p = <0.01), whose FDG levels were similar to those of control subjects. At ROC analysis performed on all image dataset, optimal cut-off levels of regional and global FDG vascular uptake provided a good discrimination between 25 patients at diagnosis and 15 control subjects (aSUV greater than 0.697; PPV = 92.3; NPV = 92.9). Major overlap was observed among FDG levels of 21 patients with active disease and in remission (aSUV greater than 0.653; PPV = 58.3; NPV = 94.1). Similar performances of visual and semiquantitative analyses were found when areas under curves (AUCs) were compared. CONCLUSIONS: (18)F-FDG PET/CT has a promising role in grading inflammation in patients with large arteries vasculitis. Nevertheless, a cut-off based analysis of FDG vascular uptake is not sufficient to separate patients with active and inactive disease during follow-up.