Jorge Oldan

Early cardiac perfusion defects after left-sided radiation therapy for breast cancer: is there a volume response?

PurposeCardiac single-photon emission computed tomography (SPECT) is often used to identify defects in myocardial perfusion due to atherosclerotic coronary artery disease. It was also used in studies to evaluate radiation therapy (RT)-associated cardiac abnormalities. In the current review, we aim to evaluate the rates of post-RT cardiac SPECT early perfusion abnormalities and relate this to the irradiated left ventricular volume.MethodsThe studies cited in this systematic review were identified using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.ResultsSix studies between 1996 and 2016 fulfilled the inclusion criteria. The reported perfusion defects in these studies were seen in the apical and anterolateral aspects of the left ventricle. Three studies show correlation between the percent of the left ventricle within the RT-field and percent of patients with early perfusion defects on cardiac SPECT. In two studies that used cardiac sparing techniques (such as deep inspiration), that resulted in a low mean heart dose, no perfusion defects were noted.ConclusionsData suggest that incidental irradiation of the heart in cases of left breast/chest wall RT can result in early post-RT perfusion defects on cardiac SPECT. There appears to be strong dose/volume dependence to the risk, and hence techniques to reduce cardiac exposure are recommended.

PET/MR Imaging of Multiple Myeloma

PET-magnetic resonance (MR) is a hybrid imaging modality that combines PET and MR. Evidence for this new modality is in the process of being developed, but both component modalities are well tested in the diagnosis and management of multiple myeloma. It allows advanced bimodality imaging of the whole body with an adaptable field of view and it can be used for monitoring plasma cell dyscrasias for progression to multiple myeloma, for assessing disease burden in patients with known multiple myeloma, for assessing response to therapy and relapse after remission, and for radiation therapy treatment planning.

FDG PET/CT Imaging of Prostate Carcinosarcoma.

We present a case of carcinosarcoma of the prostate. Workup of urinary retention after a previously treated squamous cell carcinoma of the prostate led to a transurethral prostate resection revealing carcinosarcoma of the prostate, which on F-FDG PET/CT demonstrated moderate to high avidity of this atypical prostate cancer, with partial obstruction of the urinary system and lung metastases. While FDG PET is not avid for typical prostatic adenocarcinomas, it should be considered for evaluation of atypical prostate cancers.

Predictors of survival in 211 patients with stage IV pulmonary and gastroenteropancreatic mIBG positive neuroendocrine tumors treated with I-131 mIBG

This retrospective analysis identifies predictors of survival in a cohort of patients with meta-iodobenzylguanidine (MIBG)–positive stage IV pulmonary and gastroenteropancreatic neuroendocrine tumor (P/GEP-NET) treated with 131I-MIBG therapy, to inform treatment selection and posttreatment monitoring. Methods: Survival, symptoms, imaging, and biochemical response were extracted via chart review from 211 P/GEP-NET patients treated with 131I-MIBG between 1991 and 2014. For patients with CT follow-up (n = 125), imaging response was assessed by RECIST 1.1 if images were available (n = 76) or by chart review of the radiology report if images could not be reviewed (n = 49). Kaplan–Meier analysis and Cox multivariate regression estimated survival and progression-free survival benefits predicted by initial imaging, biochemical response, and symptomatic response. Results: All patients had stage IV disease at the time of treatment. Median survival was 29 mo from the time of treatment. Symptomatic response was seen in 71% of patients, with the median duration of symptomatic relief being 12 mo. Symptomatic response at the first follow-up predicted a survival benefit of 30 mo (P < 0.001). Biochemical response at the first clinical follow-up was seen in 34% of patients, with stability of laboratory values in 48%; response/stability versus progression extended survival by 40 mo (P < 0.03). Imaging response (20% of patients) or stability (60%) at the initial 3-mo follow-up imaging extended survival by 32 mo (P < 0.001). Additionally, multiple 131I-MIBG treatments were associated with 24 mo of additional survival (P < 0.05). Conclusion: Therapeutic 131I-MIBG for metastatic P/GEP-NETs appears to be an effective means of symptom palliation. Imaging, biochemical, and symptomatic follow-up help prognosticate expected survival after 131I-MIBG therapy. Multiple rounds of 131I-MIBG are associated with prolonged survival.

Subsequent experience in hybrid PET-MRI for evaluation of refractory focal onset epilepsy

PURPOSE Epilepsy surgery is the most successful method of treating medically unresponsive epilepsy, but carries a risk of morbidity. PET/MR is an emerging technique that increases detection of focal lesions whose resection may result in symptom remission. METHODS Retrospective review of 74 focal epilepsy patients over a period of 3 years who had a PET/MR was performed following IRB permission and informed consent. 27 patients underwent surgery or RNS (responsive neurostimulator) placement. RESULTS Hybrid PET-MR identified new anatomic or functional lesions in 10 patients not identified with standalone 3 T MR. Of the 27 patients who underwent focal surgery (19) or RNS placement (8), 24 showed improvement (Engels I-III), 2 did not (Engels IV), and one had an RNS explanted due to infection. MR and PET were read by 2 separate neuroradiologists and nuclear medicine physicians, respectively. Modalities were evaluated in terms of ability to detect the correct lobe and side for a focal lesion whose resection improved symptoms. Prior standalone MR exhibited 71-77% sensitivity and 0% specificity (as there were only 2 nonresponders), MR associated with PET/MR had 68-71% sensitivity and 0-50% specificity (depending on whether a lesion was seen on one of the nonresponders), and PET had 68-71% sensitivity and 25-33% specificity. Using either PET or MR to identify a focal lesion, PET/MR had sensitivity of 78-82% and specificity 0-50%. CONCLUSIONS PET-MR provides additional sensitivity when used as two combined modalities for detecting possible epileptic foci.

18F-FDG PET/CT Imaging of Hidradenocarcinoma Arising From Preexisting Hidradenoma of the Knee

Malignant tumors of the sweat glands are exceedingly rare and aggressive tumors. We present here a case of a 60-year-old man with a malignant hidradenocarcinoma that developed in a background of preexisting benign hidradenoma on the lateral aspect of the knee that was initially resected, but rapidly recurred with associated inguinal lymphadenopathy. F-FDG PET/CT was performed as part of preoperative staging, which demonstrated abnormal inguinal lymph nodes and metastatic disease to the lungs. FDG PET/CT can play an invaluable role in the initial staging and follow-up of this rare malignancy.

Role of preoperative cardiac CT in the evaluation of infective endocarditis: comparison with transesophageal echocardiography and surgical findings

Background Significant improvement of computed tomography (CT) technology in the last decade has led to more use of this modality for evaluating infective endocarditis (IE) especially since the introduction of high resolution electrocardiogram (ECG) synchronized multiphasic (4D) acquisition. While there are a number of reports on the accuracy and value of 4D CT for evaluation of IE, there is no published data regarding the performance of single-phase ECG gated CT for assessment of IE. The purpose of this study is to evaluate the sensitivity and specificity of preoperative single-phase ECG-gated CT imaging versus transesophageal echocardiography (TEE) in the assessment of complications related to IE, with comparison to surgical findings. Methods Among 899 patients with surgically proven IE in our database, 122 underwent contrast-enhanced ECG cardiac CT and were included in the study; 84 of these patients also underwent TEE. Results Overall, there was no significant difference between CT and TEE in the identification of pseudoaneurysm/abscess and dehiscence. For the detection of pseudoaneurysm/abscess in prosthetic valves, CT demonstrated higher sensitivity (81% vs. 64%) and specificity (75% vs. 33%) in patients with mechanical aortic valves; TEE demonstrated marginally higher sensitivity (72% vs. 63%) and specificity (80% vs. 73%) in patients with bioprosthetic aortic valves, although the differences are not statistically significant. TEE demonstrated significantly higher sensitivity (85% vs. 16%) in identifying vegetation in all patients (P<0.0001), including patients with prosthetic valves (sensitivity, 78% vs. 19%). The combined imaging findings of CT and TEE demonstrated improved sensitivity in identifying pseudoaneurysm/abscess and slightly improved detection of prosthesis dehiscence. Conclusions Preoperative single-phase gated CT can be seen as complementary to TEE in assessing complications of suspected IE or may be substituted for TEE when vegetation or dehiscence is depicted on transthoracic echocardiography and the patient has a contraindication to TEE.

Imaging Modalities in the Diagnosis of Recurrent or Metastatic Thyroid Cancer

The imaging of thyroid cancer takes a multimodality approach, and this is particularly the case for the workup of recurrent and metastatic disease. Ultrasound can be used to look for regional nodes or evaluate palpable lesions. Cross-sectional imaging such as computed tomography (CT) and magnetic resonance [MR] can look for disease in the neck as well as throughout the body. Total body iodine scans with low-dose 123I or 131I can be used for evaluating residual functioning tissue following total thyroidectomy prior to radioiodine ablation and can also be used to detect nodal and distant metastatic disease in high-risk patients; some iodine-avid metastases may not be visible on CT or MR imaging. In high-risk patients, total body iodine (TBI) scans can help determine the appropriate 131I dose for radioablation. TBI scans can also be used to evaluate patients suspected of having recurrent disease following ablation (e.g., rising serum thyroglobulin). Tumors that are not visible on TBI in spite of elevated thyroglobulin may have become less well differentiated and may no longer metabolize iodide. These patients may benefit from fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scanning, since FDG accumulates in dedifferentiated tumors.

Applications of PET/MR Imaging in Urogynecologic and Genitourinary Cancers

Positron emission tomograph (PET)-magnetic resonance (MR) is a new modality combining PET and MR. In gynecologic cancers it can be used for staging of cervical and endometrial cancer, planning of radiation therapy in cervical cancer, assessing response to chemotherapy in ovarian cancer, and detection of recurrence in most gynecologic cancers. It is being explored for prostate cancer and other genitourinary cancers, but is still in experimental stages.

Pediatric Applications of Hybrid PET/MR Imaging

Hybrid PET/MR imaging systems have recently become available for clinical practice. The simultaneous physiologic and anatomic imaging offers the potential to reduce radiation dose and other advantages for pediatric patients. Issues more unique to pediatric imaging, however, must also be addressed, including imaging time and disease sensitivity. Combined with newer tracers and a concerted multidisciplinary effort, the approach has the potential to substantially improve the imaging of a variety of pediatric diseases.