Past and Future of Ga-citrate for Infection and Inflammation Imaging.

Both 67Ga and 68Ga-citrates are used to detect a wide spectrum of pathology consisting of various inflammatory, infectious and malignant conditions. Considering the now widespread availability and constantly increasing demand for PET/CT studies,68Ga-citrate is gaining ground in clinical settings and the added value of combined metabolic and anatomical imaging achieved by combining PET with Computed Tomography (CT) to PET/CT makes 68Ga-citrate particularly promising. Despite the tracer's non-specificity, it has demonstrated potential especially in the evaluation of various infectious and inflammatory skeletal- and lung conditions. In this review, we will focus on the indications and lessons learned from 67Ga, and present the current status for the use of 68Ga-citrate PET/CT in selected inflammation and infectious diseases based on the limited literature available.

The Utility of 99mTechnetium-mercaptoacetyltriglycine Renogram in Assessing the Baseline Renal Function of a Rare Incidental Ectopic Thoracic Kidney.

Ectopic thoracic kidney is an extremely rare condition caused by the abnormal location of one or both kidneys in the thoracic cavity. They are usually discovered incidentally on routine imaging. Although commonly asymptomatic, thoracic kidneys are at a risk of malrotation, pelviureteric junction obstruction, and subsequent obstructive nephropathy, by virtue of their long pedicle. We present a case report of an incidental thoracic kidney, for which a 99mtechnetium-mercaptoacetyltriglycine (99mTc-MAG3) renogram was performed to assess the baseline renal function. Although few reports are published in the literature using 99mTc-MAG3 renogram for this indication, we demonstrate a safe and feasible study to establish a baseline assessment of renal function in this group of patients.

Evaluation and Identification of Lumbosacral Transitional Vertebra Causing Intractable Low Back Pain Utilizing Bone Single-Photon Emission Tomography with Computed Tomography.

The cause of low back pain due to lumbosacral transitional vertebra (LSTV) still remains a debated topic. Functional imaging with bone scintigraphy has been a valuable adjunct in its assessment; however, in recent years, the additional utility of single-photon emission tomography with computed tomography (SPECT/CT) is evolving as the imaging modality of choice in identifying range of complex lower back pain sources, leading to the provision of suitable treatment options. We present a case demonstrating a variant type of LSTV as a source of pain localized and delineated on hybrid SPECT/CT imaging treated by minimally invasive microendoscopic resection of the pseudoarticulations.

Investigating the role of SPECT/CT in dynamic sentinel lymph node biopsy for penile cancers.

PURPOSE: Currently, most centres use 2-D planar lymphoscintigraphy when performing dynamic sentinel lymph node biopsy in penile cancer patients with clinically impalpable inguinal nodes. This study aimed to investigate the role of SPECT/CT following 2-D planar lymphoscintigraphy (dynamic and static) in the detection and localization of sentinel lymph nodes in the groin. METHODS: A qualitative (visual) review was performed on planar followed by SPECT/CT lymphoscintigraphy in 115 consecutive patients (age 28-86 years) who underwent injection of 99mTc-nanocolloid followed by immediate acquisition of dynamic (20 min) and early static scans (5 min) initially and further delayed static (5 min) images at 120 min followed by SPECT/CT imaging. The lymph nodes detected in each groin on planar lymphoscintigraphy and SPECT/CT were compared. RESULTS: A total of 440 and 467 nodes were identified on planar scintigraphy and SPECT/CT, respectively. Overall, SPECT/CT confirmed the findings of planar imaging in 28/115 cases (24%). In the remaining 87 cases (76%), gross discrepancies were observed between planar and SPECT/CT images. SPECT/CT identified 17 instances of skin contamination (16 patients, 13%) and 36 instances of in-transit lymphatic tract activity (24 patients, 20%) that had been interpreted as tracer-avid lymph nodes on planar imaging. In addition, SPECT/CT identified 53 tracer-avid nodes in 48 patients (42%) that were not visualized on planar imaging and led to reclassification of the drainage basins (pelvic/inguinal) of 27 tracer-avid nodes. CONCLUSIONS: The addition of SPECT/CT improved the rate of detection of true tracer-avid lymph nodes and delineated their precise (3-D) anatomic localization in drainage basins.

Painful knee prosthesis: can we help with bone SPECT/CT?

OBJECTIVES: The aim of the study was to evaluate the value of single-photon emission computerized tomography/computed tomography (SPECT/CT) in the clinical assessment of painful knee prostheses. MATERIALS AND METHODS: Between 2009 and 2011 we identified 105 patients who had undergone Tc-hydroxydiphosphonate SPECT/CT for painful knee prosthesis. Complete follow-up data were available for 69 patients (50 women and 19 men; mean age, 71 years) with painful knee prostheses (59 total, nine unicompartmental, one patellofemoral) and clinical suspicion of infection or loosening. The imaging test report in conjunction with the clinical data from the patient's notes was used to gauge how useful the test had been in terms of patient management. RESULTS: SPECT/CT confirmed the suspected clinical diagnosis of loosening in nine patients (13%) and of infection in two (2.9%) and identified other causes in 43 patients (62.3%). In 85.5% of patients, SPECT/CT was clinically useful (both positive and negative results), whereas in 14.5% it had no clinical impact on patient management. Revision surgery was performed in 24/69 (34.8%) patients and confirmed the SPECT/CT diagnosis in 21 patients (seven loosening, one infection, two subchondral fractures, two postoperative inflammation and nine patellofemoral osteoarthritis). CONCLUSION: SPECT/CT is a useful tool for the evaluation of painful knee prosthesis in 85.5% of cases and helps in confirming mechanical loosening and in excluding other causes such as infection and patellofemoral osteoarthritis.

Diffusion-weighted MRI of lymphoma: prognostic utility and implications for PET/MRI?

PURPOSE: With the recent introduction of PET/MRI, we investigated whether diffusion-weighted imaging (DWI) can complement PET for predicting local treatment response in Hodgkin lymphoma. METHODS: This retrospective study included 39 patients selected from a hospital database with a histological diagnosis of Hodgkin lymphoma undergoing whole-body MRI (supplemented by DWI) and PET/CT before and after two cycles of vincristine, etoposide, prednisolone and doxorubicin (OEPA). The pretreatment volume, MRI apparent diffusion coefficient (ADC) and PET maximum standardized uptake value (SUV(max)) of the largest nodal mass were determined quantitatively for evaluation of the local response following two cycles of OEPA. Quantitative pretreatment imaging biomarkers (disease volume, ADC, SUV(max)) were compared between sites with an adequate and those with an inadequate response using Fisher's exact test and Mann Whitney statistics. Multivariate models predictive of an inadequate response based on demographic/clinical features, pretreatment disease volume and SUV(max) without (model 1) and with (model 2) the addition of ADC were derived and crossvalidated. The ROC area under curve (AUC) was calculated for both models using the full dataset (training) and the crossvalidation (test) data. RESULTS: Sites with an adequate response had a significantly lower median pretreatment ADC (1.0 × 10(-3)mm(2)s(-1)) than those with an inadequate response (1.26 × 10(-3)mm(2)s(-1); p < 0.01). There were no significant differences in patient demographic/clinical parameters, pretreatment SUV(max) or pretreatment nodal volume between sites with inadequate and adequate response. The ROC-AUCs for prediction of an inadequate response for the training and test data for model 1 were 0.90 and 0.53, and for model 2 were 0.84 and 0.71, respectively. CONCLUSION: DWI complements PET for prediction of site-specific interim response to chemotherapy.