Targeted Radiation Delivery before Haploidentical HCT for High-risk Leukemia or MDS Patients Yields Long-term Survivors.

PURPOSE: Hematopoietic cell transplantation (HCT) has curative potential for myeloid malignancies, though many patients cannot tolerate myeloablative conditioning with high-dose chemotherapy alone or with total-body irradiation (TBI). Here we report long-term outcomes from a phase I/II study using iodine-131 (131I)-anti-CD45 antibody BC8 combined with nonmyeloablative conditioning prior to HLA-haploidentical HCT in adults with high-risk relapsed/ refractory acute myeloid or lymphoid leukemia (AML or ALL), or myelodysplastic syndrome (MDS; ClinicalTrials.gov, NCT00589316). PATIENTS AND METHODS: Patients received a tracer diagnostic dose before a therapeutic infusion of 131I-anti-CD45 to deliver escalating doses (12-26 Gy) to the dose-limiting organ. Patients subsequently received fludarabine, cyclophosphamide (CY), and 2 Gy TBI conditioning before haploidentical marrow HCT. GVHD prophylaxis was posttransplant CY plus tacrolimus and mycophenolate mofetil. RESULTS: Twenty-five patients (20 with AML, 4 ALL and 1 high-risk MDS) were treated; 8 had ≥ 5% blasts by morphology (range 9%-20%), and 7 had previously failed HCT. All 25 patients achieved a morphologic remission 28 days after HCT, with only 2 patients showing minimal residual disease (0.002-1.8%) by flow cytometry. Median time to engraftment was 15 days for neutrophils and 23 days for platelets. Point estimates for overall survival and progression-free survival were 40% and 32% at 1 year, and 24% at 2 years, respectively. Point estimates of relapse and nonrelapse mortality at 1 year were 56% and 12%, respectively. CONCLUSIONS: 131I-anti-CD45 radioimmunotherapy prior to haploidentical HCT is feasible and can be curative in some patients, including those with disease, without additional toxicity.

Skin Malignancies: Imaging Review with Radiologic-Histopathologic Correlation.

Skin malignancies are commonly encountered as primary or incidental findings. Neoplasms that affect the skin include primary (basal cell carcinoma, squamous cell carcinoma, melanoma, and Merkel cell carcinoma) and secondary (mesenchymal neoplasms, lymphoma, and metastases) tumors. Imaging provides valuable anatomic information (tumor size, depth of involvement, presence of distant metastasis, and data for guiding biopsy) and functional information (metabolic activity and sentinel node mapping data). This information, in addition to biopsy results, improves the histopathologic characterization of tumors and treatment planning. Various histopathologic types of the same entity exhibit different biologic behavior and have different imaging features. Familiarity with the multimodality imaging features, histopathologic characteristics, and various modes of dissemination (direct invasion; perineural, lymphatic, and hematogenous spread) of the most common skin malignancies helps radiologists narrow the differential diagnosis in clinical practice. ©RSNA, 2023 Supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Pictorial Summary of Congenital Gallbladder and Biliary Duct Anomalies Presentation on HIDA Imaging.

Hepatobiliary iminodiacetic acid (HIDA) scan is one of the principal imaging modalities for the evaluation of the gallbladder and biliary tree. Congenital biliary anomalies are rare and can be difficult to recognize on HIDA scan. They may also mimic other biliary pathology. The purpose of this article is to review the spectrum of congenital gallbladder and biliary anomalies and describe their imaging appearance on HIDA scan. In addition, the diagnostic utility of functional imaging with HIDA when evaluating biliary tract anomalies is described.

Megadose 90Y-ibritumomab tiuxetan prior to allogeneic transplantation is effective for aggressive large B-cell lymphoma.

Allogeneic hematopoietic cell transplantation (allo-HCT) can be curative for relapsed or refractory B-cell lymphomas (BCLs), although outcomes are worse in aggressive disease, and most patients will still experience relapse. Radioimmunotherapy using 90Y-ibritumomab tiuxetan can induce disease control across lymphoma subtypes in a dose-dependent fashion. We hypothesized that megadoses of 90Y-ibritumomab tiuxetan with reduced-intensity conditioning could safely produce deeper remissions in aggressive BCL further maintained with the immunologic effect of allo-HCT. In this phase 2 study, CD20+ BCL patients received outpatient 90Y-ibritumomab tiuxetan (1.5 mCi/kg; maximum, 120 mCi), fludarabine, and then 2 Gy total body irradiation before HLA-matched allo-HCT. Twenty patients were enrolled after a median of 4.5 prior lines of therapy, including 14 with prior autologous transplant and 4 with prior anti-CD19 chimeric T-cellular therapy. A median 90Y-ibritumomab tiuxetan activity of 113.6 mCi (range, 71.2-129.2 mCi) was administered, delivering a median of 552 cGy to the liver (range, 499-2411 cGy). The estimated 1- and 5-year progression-free survival was 55% (95% confidence interval [CI], 31-73) and 50% (95% CI, 27-69) with a median progression-free survival of 1.57 years. The estimated 1- and 5-year overall survival was 80% (95% CI, 54-92) and 63% (95% CI, 38-81) with a median overall survival of 6.45 years. Sixteen patients (80%) experienced grade 3 or higher toxicities, although nonrelapse mortality was 10% at 1 year. No patients developed secondary acute myeloid leukemia/myelodysplastic syndrome. Megadose 90Y-ibritumomab tiuxetan, fludarabine, and low-dose total body irradiation followed by an HLA-matched allo-HCT was feasible, safe, and effective in treating aggressive BCL, exceeding the prespecified end point while producing nonhematologic toxicities comparable to those of standard reduced-intensity conditioning regimens.

Ventilation-Perfusion Scan: A Primer for Practicing Radiologists.

Lung scintigraphy, or ventilation-perfusion (V/Q) scan, is one of the commonly performed studies in nuclear medicine. Owing to variability in clinical applications and different departmental workflows, many trainees are not comfortable interpreting the results of this study. This article provides a simplified overview of V/Q imaging, including a review of its technique, interpretation methods, and established and emerging clinical applications. The authors review the role of V/Q imaging in evaluation of acute and chronic pulmonary embolism, including the role of SPECT/CT and comparing V/Q scan with CT angiography. In addition, a variety of other applications of pulmonary scintigraphy are discussed, including congenital heart disease, pretreatment planning for lung cancer and emphysema, posttransplant imaging for bronchiolitis obliterans, and less common vascular and nonvascular pathologic conditions that may be detected with V/Q scan. This article will help radiologists and residents interpret the results of V/Q scans and understand the various potential clinical applications of this study. Online supplemental material is available for this article. ©RSNA, 2021.

Yttrium-90 Anti-CD45 Immunotherapy Followed by Autologous Hematopoietic Cell Transplantation for Relapsed or Refractory Lymphoma.

Autologous hematopoietic cell transplantation (AHCT) is a standard of care for several subtypes of high-risk lymphoma, but durable remissions are not achieved in the majority of patients. Intensified conditioning using CD45-targeted antibody-radionuclide conjugate (ARC) preceding AHCT may improve outcomes in lymphoma by permitting the delivery of curative doses of radiation to disease sites while minimizing toxicity. We performed sequential phase I trials of escalating doses of yttrium-90 (90Y)-labeled anti-CD45 antibody with or without BEAM (carmustine, etoposide, cytarabine, melphalan) chemotherapy followed by AHCT in adults with relapsed/refractory or high-risk B cell non-Hodgkin lymphoma (NHL), T cell NHL (T-NHL), or Hodgkin lymphoma (HL). Twenty-one patients were enrolled (16 NHL, 4 HL, 1 T-NHL). Nineteen patients received BEAM concurrently. No dose-limiting toxicities were observed; therefore, the maximum tolerated dose is estimated to be ≥34 Gy to the liver. Nonhematologic toxicities and engraftment kinetics were similar to standard myeloablative AHCT. Late myeloid malignancies and 100-day nonrelapse deaths were not observed. At a median follow-up of 5 years, the estimates of progression-free and overall survival of 19 patients were 37% and 68%, respectively. Two patients did not receive BEAM; one had stable disease and the other progressive disease post-transplant. The combination of 90Y-anti-CD45 with BEAM and AHCT was feasible and tolerable in patients with relapsed and refractory lymphoma. The use of anti-CD45 ARC as an adjunct to hematopoietic cell transplantation regimens or in combination with novel therapies/immunotherapies should be further explored based on these and other data.

90Y-labeled anti-CD45 antibody allogeneic hematopoietic cell transplantation for high-risk multiple myeloma.

To improve disease control without increasing the toxicity of a reduced-intensity allogeneic hematopoietic cell transplantation (HCT) in multiple myeloma (MM), a phase I trial was performed using an antibody-radionuclide conjugate targeting CD45 (90Y-DOTA-BC8) as conditioning. 90Y-DOTA-BC8 was combined with fludarabine and low-dose TBI followed by allogeneic HCT in patients with MM and ≥1 adverse risk characteristic at diagnosis, relapse after autologous transplant, or plasma cell leukemia (PCL). The primary objective was to estimate the maximum tolerated radiation absorbed dose. Fourteen patients were treated (one with PCL, nine failed prior autologous HCT, and nine with ≥1 adverse cytogenetics). Absorbed doses up to 32 Gy to liver were delivered. No dose-limiting toxicities occurred. Non-hematologic toxicities were manageable and included primarily gastrointestinal (43%) and metabolic/electrolyte disturbances (36%). Treatment-related mortality at 100 days was 0%. At a median follow-up of 5 years, the overall survival was 71% (median not reached) and the progression-free survival was 41% (median 40.9 months). The incorporation of CD45-targeted radioimmunotherapy (RIT) into a reduced-intensity allogeneic HCT is well-tolerated and may induce long-term remissions among patients with poor-risk MM, supporting further development of RIT-augmented conditioning regimens for HCT.

The Peritoneum: What Nuclear Radiologists Need to Know.

The peritoneum is the largest and most complex serous membrane in the human body. The peritoneal membrane is composed of a layer of mesothelium supported by a thin layer of connective tissue. The peritoneum is one continuous sheet, forming two layers and a potential space between them - the peritoneal cavity- which is subdivided into multiple communicating spaces containing small amount of serous fluid that facilitates frictionless movement of mobile intraabdominal viscera. Peritoneum also contributes to fluid exchange mechanism and plays a role in immune response. The peritoneum is subject to many neoplastic and non-neoplastic processes including infections, trauma, developmental and inflammatory processes. Different Nuclear Medicine imaging techniques can be used to diagnose peritoneal diseases, most of these techniques can be customized depending on the clinical scenario and expected findings. Peritoneal scintigraphy can detect abnormal peritoneal communication or compartmentalization. Several nuclear medicine techniques can help characterize intraperitoneal fluid collections and differentiate sterile from infected fluid. PET imaging plays an important role in imaging of different neoplastic and non-neoplastic peritoneal pathologies. Nuclear radiologists need to be familiar with peritoneal anatomy and pathology to interpret peritoneal findings in dedicated peritoneal nuclear medicine imaging studies, as part of more general nuclear medicine scans, or on CT or MRI component of hybrid imaging studies. The purpose of this article is to review the normal peritoneal anatomy, various pathologic processes involving the peritoneum, and different nuclear medicine and hybrid imaging techniques that can help detect, characterize, and follow up peritoneal pathology.

Mesenteric panniculitis mimicking early recurrence at end-of-treatment evaluation in malignant lymphoma: Differentiation by active surveillance with F-18 FDG PET/CT imaging.

Mesenteric panniculitis is a relatively rare fibro-inflammatory condition of the mesentery. In acute phase, it demonstrates avid uptake on Fluorine-18 FDG PET/CT (PET/CT). Thorough assessment is needed to differentiate from viable or recurrent disease in patients with malignant lymphoma because it mimics active lymphomatous disease on PET/CT. In this article, 3 illustrative cases of malignant lymphoma are presented. PET/CT demonstrated new FDG-avid mesenteric lesions at the end-of-treatment evaluation while the original disease showed significant response. Early recurrence was initially suspected, but together with clinical course and findings, active surveillance was opted. Sequential follow-up PET/CTs showed various patterns of metabolic activity over time; it can persist for months or more, or metabolic activity can fluctuate over time. Eventually benignity was confirmed in these cases. These cases underscore the importance of interpretation with clinical context and awareness of chronological metabolic changes of mesenteric panniculitis to determine proper management.

Biokinetics of Radiolabeled Monoclonal Antibody BC8: Differences in Biodistribution and Dosimetry Among Hematologic Malignancies.

We reviewed 111In-DOTA-anti-CD45 antibody (BC8) imaging and bone marrow biopsy measurements to ascertain the biodistribution and biokinetics of the radiolabeled antibody and to investigate differences based on type of hematologic malignancy. Methods: Serial whole-body scintigraphic images (4 time points) were obtained after infusion of the 111In-DOTA-BC8 (176-406 MBq) into 52 adult patients with hematologic malignancies (lymphoma, multiple myeloma, acute myeloid leukemia, and myelodysplastic syndrome). Counts were obtained for the regions of interest for spleen, liver, kidneys, testicles (in men), and 2 marrow sites (acetabulum and sacrum), and correction for attenuation and background was made. Bone marrow biopsies were obtained 14-24 h after infusion, and the percentage of administered activity was determined. Absorbed radiation doses were calculated. Results: Initial uptake in liver averaged 32% ± 8.4% (SD) of administered activity (52 patients), which cleared monoexponentially with a biologic half-time of 293 ± 157 h (33 patients) or did not clear (19 patients). Initial uptake in spleen averaged 22% ± 12% and cleared with a biologic half-time of 271 ± 185 h (36 patients) or longer (6 patients). Initial uptake in kidney averaged 2.4% ± 2.0% and cleared with a biologic half-time of 243 ± 144 h (27 patients) or longer (9 patients). Initial uptake in red marrow averaged 23% ± 11% and cleared with a biologic half-time of 215 ± 107 h (43 patients) or longer (5 patients). Whole-body retention half-time averaged 198 ± 75 h. Splenic uptake was higher in the AML/MDS group than in the lymphoma group (P ≤ 0.05) or the multiple myeloma group (P ≤ 0.10). Liver represented the dose-limiting organ. For liver uptake, no significant differences were observed among the 3 malignancy groups. Average calculated radiation absorbed doses per unit of administered activity for a therapy infusion of 90Y-DOTA-BC8 were 0.35 ± 0.20 cGy/MBq for red marrow, 0.80 ± 0.24 cGy/MBq for liver, 3.0 ± 1.4 cGy/MBq for spleen, 0.055 ± 0.014 cGy/MBq for total body, 0.21 ± 0.15 cGy/MBq for osteogenic cells, and 0.17 ± 0.15 cGy/MBq for kidneys. Conclusion:111In-DOTA-BC8 had a long retention time in liver, spleen, kidneys, and red marrow, and the highest absorbed doses were in spleen and liver. Few differences were observed by malignancy type. The exception was greater splenic uptake in the leukemia/MDS group than in the lymphoma or multiple myeloma group.

A case of multiple aggressive osseous hemangiomas on bone scan.

A 49-year-old male with worsening back and right leg pain was referred for bone scan imaging. Bone scan demonstrated multifocal expansile osteoblastic bony lesions, atypical for benign osseous hemangiomas, which are commonly cold on bone scan. Multisite bone biopsies were compatible with the diagnosis of multifocal osseous hemangiomas. This case illustrates that aggressive osseous hemangiomas, a rare subtype of hemangiomas, may have variable osteoblastic activity on bone scan, ranging from mild to severe uptake.

Apical variant hypertrophic cardiomyopathy "multimodality imaging evaluation".

Apical variant hypertrophic cardiomyopathy (AHCM) is characterized by asymmetric hypertrophy of the left ventricular (LV) apex. T wave inversions of variable degree, particularly in the left precordial leads, and left ventricular hypertrophy (LVH) are common EKG findings in AHCM. Echocardiography is typically the initial imaging modality used in the diagnosis and evaluation of AHCM. The diagnosis is made when the LV apex has apical wall thickness of ≥ 15 mm or a ratio of apical to basal LV wall thickness of ≥ 1.3 at end-diastole. The use of microbubble contrast agents with echocardiography is helpful for visualization of the apex. Cardiac magnetic resonance (CMR) has the advantage of a large field of view and the ability to perform tissue characterization. Late gadolinium enhancement (LGE) sequences are essential in the assessment of potential areas of myocardial scarring. Cardiac computed tomography (CCT) has the advantage of being able to evaluate coronary arteries in addition to assessing cardiac anatomy and function. A "Solar Polar" map pattern is the characteristic feature of AHCM on myocardial perfusion imaging (MPI) in cases not associated with apical aneurysm (APA). Recognition of typical perfusion patterns in AHCM patients is not only important in the diagnostic evaluation of this disease process, but also for avoiding unnecessary and costly tests. The purpose of this article is to review the imaging features of AHCM from different imaging modalities and assess the value added of each modality in the diagnosis of AHCM.

18F-Fluciclovine Uptake in Celiac Ganglia: A Pitfall in Prostate Cancer PET Imaging.

We present 4 cases of patients who underwent F-fluciclovine PET for prostate cancer demonstrating physiologic uptake in the celiac ganglia, which could be mistaken for metastatic lymphadenopathy if the celiac ganglia have a nodular configuration and uptake higher than bone marrow. Uptake in celiac, cervical, and sacral ganglia has been reported previously as an important pitfall in Ga-PSMA-HBED-CC PET for prostate cancer. In our patients, only celiac ganglion uptake was visualized. Advances in PET scanner technology may cause physiologic uptake of F-fluciclovine in celiac ganglia to become more visually distinguishable from muscular uptake in adjacent diaphragmatic crura.

Multimodality imaging evaluation for iliac crest apophysis avulsion injury.

A young cross-country athlete with left thigh pain, and a recent negative MRI of the left hip was referred to nuclear medicine for bone scan imaging. A 3-phase Tc-99m methylene diphosphonate bone scan was performed and revealed left iliac crest apophysis avulsion. This case illustrates that 3-phase bone scan is a great adjunct in the evaluation of sports injuries especially in athletes presenting with vague nonlocalizing symptoms, and prior negative radiographic or MRI imaging.

Functional Liver Imaging and Dosimetry to Predict Hepatotoxicity Risk in Cirrhotic Patients With Primary Liver Cancer.

PURPOSE: Mitigating radiation-induced liver disease (RILD) is an ongoing need in patients with hepatocellular carcinoma. We hypothesize that [99mTc]-sulfur colloid (SC) single photon emission computed tomography (SPECT)/computed tomography (CT) scans can provide global functional liver metrics and functional liver dosimetric parameters that are predictive of hepatotoxicity risk in patients with primary liver cancer with cirrhosis. MATERIALS AND METHODS: We retrospectively reviewed 47 patients (n = 26 proton, n = 21 stereotactic body radiation therapy) with Child-Pugh (CP)-A (62%) or CP-B (38%) cirrhosis who underwent SC SPECT/CT scans for radiation therapy planning. SC SPECT scans were mined for image intensity threshold-based functional liver volumes (FLV), mean liver-spleen uptake ratio (L/Smean), and total liver function (TLF = FLV*L/Smean). Radiation therapy doses were voxel-wise converted to the biologically equivalent dose (EQD2a/b=3) and relative biological effectiveness (GyRBE). Normal liver (liver minus gross tumor volume [GTV]) and FLV mean doses, absolute and relative dose-volumes (VGy[cc], VGy[%]), and relative dose-function histogram quantiles in 10 GyEQD2 increments were calculated. Logistic regression was performed for correlation to CP score increase of 2 or higher (CP+2). Cox regression was performed for correlation to RILD-specific survival (RILD-SS) and overall survival. RESULTS: The strongest predictors of RILD-SS were FLV V20 and liver-GTV F20. FLV mean dose, but not CT-derived anatomic mean dose, was predictive of RILD-SS. TLF and L/Smean were the only parameters that were associated with CP+2 after adjusting for baseline CP score. Optimal cutoffs to mitigate risk RILD-SS were identified: FLV mean dose <23 GyEQD2, liver-GTV V20 <36%, FLV V20 <36%, liver-GTV F20 <36%, FLV <32% (350 cc), L/Smean >0.75, TLF >0.60, tumor volume <40 cm3, and CP score A5-6 versus B7-C10. A narrower therapeutic window was observed in CP-B/C patients. The discriminatory power for RILD-SS within CP-B/C classes was improved with the addition of a functional dosimetric constraint, resulting in low- and high-risk subgroups (P = 3 × 10-6). CONCLUSIONS: Functional liver metrics and dosimetric parameters derived from pretreatment SC SPECT/CT scans were complementary predictors of hepatotoxicity and may provide useful clinical decision support in the management of cirrhotic patients with primary liver cancer.

MDP-SPECT Versus Hybrid MDP-SPECT/CT in the Evaluation of Suspected Pars Interarticularis Fracture in Young Athletes.

BACKGROUND AND PURPOSE: To assess benefits of hybrid (single photon emission computerized tomography [SPECT]/computed tomography [CT]) imaging over SPECT imaging only in the management of young athletes with low back pain (LBP) due to suspected pars interarticularis fracture. METHODS: Retrospectively reviewed medical records of 163 consecutive patients who had radionuclide SPECT imaging for evaluation of LBP between January 1, 2010 and December 30, 2015. All enrolled patients were divided into two groups (group 1: patients with radionuclide SPECT imaging only and group 2: patients with radionuclide hybrid imaging). Radiation dose, cost benefits, and mean duration of delay in complete diagnosis were assessed and compared using Fisher's exact test. RESULTS: A total of 91 patients were enrolled after applying inclusion and exclusion criteria. The volume CT dose index and dose length product (DLP) estimated for a scan length of 10 cm (DLP 10) were significantly lower for patients in group II (CTDIvol ) (P  =  .001 and P  =  .001). Although, there was no significant difference in actual DLP (P  =  .52). There was a median delay of 7 days (interquartile range 2-10 days) for complete diagnosis in group I patients. Least expensive imaging for early definitive diagnosis required for the treatment decisions was in patients who had a radionuclide Technetium-99m methylene diphosphonate bone scan with limited lumbar spine planar and SPECT imaging followed by a thin slice, limited CT performed only when SPECT imaging was positive for an active pars interarticularis fracture. No significant difference in the management of patients between the groups (P  =  .47). CONCLUSION: Hybrid imaging should be preferred over SPECT only imaging for initial evaluation of suspected pars interarticularis fracture in young athletes with LBP.

Regional Radiation Dose-Response Modeling of Functional Liver in Hepatocellular Carcinoma Patients With Longitudinal Sulfur Colloid SPECT/CT: A Proof of Concept.

PURPOSE: Hepatotoxicity risk in patients with hepatocellular carcinoma (HCC) is modulated by radiation dose delivered to normal liver tissue, but reported dose-response data are limited. Our prior work established baseline [99mTc]sulfur colloid (SC) single-photon emission computed tomography (SPECT)/computed tomography (CT) liver function imaging biomarkers that predict clinical outcomes. We conducted a proof-of-concept investigation with longitudinal SC SPECT/CT to characterize patient-specific radiation dose-response relationships as surrogates for liver radiosensitivity. METHODS AND MATERIALS: SC SPECT/CT images of 15 patients with HCC with variable Child-Pugh (CP) status (8 CP-A, 7 CP-B/C) were acquired in treatment position before and 1 month (nominal) after stereotactic body radiation therapy (n = 6) or proton therapy (n = 9). Localized rigid registrations between pre/posttreatment CT to planning CT scans were performed, and transformations were applied to pre/posttreatment SC SPECT images. Radiation therapy doses were converted to EQD2 and Gy RBE (relative biological effectiveness) and binned in 5 GyEQD2 increments within tumor-subtracted livers. Mean dose and percent change (%ΔSC) between pre- and posttreatment SPECT uptake, normalized to regions receiving <5 GyEQD2, were calculated in each binned dose region. Dose-response data were parameterized by sigmoid functions (double exponential) consisting of maximum reduction (%ΔSCmax), dose midpoint (Dmid), and dose-response slope (αmid) parameters. RESULTS: Individual patient sigmoid dose-response curves had high goodness-of-fit (median R2 = 0.96, range 0.76-0.99). Large interpatient variability was observed, with median (range) in %ΔSCmax of 44% (20%-75%), Dmid of 13 Gy (4-27 GyEQD2), and αmid of 0.11 GyEQD2-1 (0.04-0.29 GyEQD2-1), respectively. Eight of 15 patients had %ΔSCmax of 20% to 45%, whereas 7 of 15 had %ΔSCmax of 60% to 75%, with subgroups made up of variable baseline liver function status and radiation treatment modality. Fatal hepatotoxicity occurred in patients (2 of 15) with low total liver funcation (<0.12) and low Dmid (<7 GyEQD2). CONCLUSIONS: Longitudinal SC SPECT/CT imaging revealed patient-specific variations in dose-response and may identify patients with poor baseline liver function and increased sensitivity to radiation therapy. Validation of this regional liver dose-response modeling concept as a surrogate for patient-specific radiosensitivity has potential to guide HCC therapy regimen selection and planning constraints.

I-123 DaTscan SPECT Brain Imaging in Parkinsonian Syndromes: Utility of the Putamen-to-Caudate Ratio.

BACKGROUND AND PURPOSE: Computer-based analysis of Dopamine transporter imaging (DaTscan) can aid in image interpretation. In this study, we examined the distribution of putamen-to-caudate ratios (PCRs) obtained by using a clinically available semiquantification method. METHODS: Medical records of 32 patients (M:16) with a diagnosis of Parkinson's disease (PD) (n = 22) or Parkinson's plus syndromes (PPS) (n = 10) based on clinical follow-up, were retrospectively reviewed. Single photon emission tomography (SPECT) imaging was performed 4 hours after intravenous injection of 3-5 mCi [I-123]-ioflupane. Semiquantitative evaluation using DaTQUANT software was performed. Utility of PCR with a cutoff of .7 and .8 in the diagnosis of nigrostriatal degeneration was assessed. PD and PPS groups based on clinical assessment and caudate-to-background ratio (CBR) were assessed separately. RESULTS: Minimum PCR for both hemispheres was .74 ± .09 (Mean ± SD, range: .58-.89), with 65.63% patients (21/32) having PCR > .7. Mean PCR in mild nigrostriatal degeneration was .77 ± .08 (range: .62-.89) and in advanced nigrostriatal degeneration was .73 ± .09 (range: .58-.89). Mean PCR in PD group was .73 ± .09 (range: .58-.89) and in PPS group was .75 ± .10 (range: .61-.88). CONCLUSIONS: Although PCR can intrinsically be a useful indication of disease, this ratio obtained in our analysis by using one of the clinically available automatic semiquantitative methods has large variability and might not be a reliable numeric marker in interpretation of [I-123]ioflupane studies. This may be due to difficulty in separating caudate from putamen on SPECT images, as well as the nonuniform decreased Ioflupane uptake in both putamen and caudate.

Hepatopulmonary shunting on Tc99m-MAA liver mapping: correlation with dynamic cross-sectional imaging and description of different shunting patterns.

PURPOSE: The purpose of the study was to correlate lung shunt fraction (LSF) calculated by intra-arterial injection of Technetium-99m (Tc-99m)-labeled macroaggregated albumin (MAA) in a hepatic artery branch with the presence of certain patterns of vascular shunts on dynamic CT or MRI of the liver. METHODS: This retrospective study was approved by the institutional review board and informed consent was waived. We reviewed 523 MAA scans in 453 patients (301 men, 152 women) performed from July 2007 to June 2015 and their correlative cross-sectional imaging. Patterns of vascular shunts on dynamic CT or MRI performed within 3 months of the MAA study and that potentially divert hepatic arterial inflow to the systemic venous return were defined as "target shunts." Dynamic CT or MRI was classified into three groups with target shunt present, absent, or indeterminate. The mean LSF was compared across the first and second groups using paired t test. RESULTS: 342 CT and MRI studies met inclusion criteria: target shunts were present in 63 studies, absent in 271 studies, and 8 studies were indeterminate. When target shunts were visualized, the mean LSF on corresponding MAA scans was 12.9 ± 10.36% (95% CI 10.29-15.15%) compared to 4.3 ± 3.17% (95% CI 3.93-4.68%) when no target shunt was visualized. The difference was statistically significant (p value < 0.001). Identified target shunts were either direct (arteriohepatic venous shunt) or indirect (arterioportal shunt combined with a portosystemic shunt). CONCLUSIONS: Visualizing certain patterns of vascular shunting on a dynamic CT or MRI scan is associated with high LSF.

Biliary Leak in the Postsurgical Abdomen: A Primer to HIDA Scan Interpretation.

Postsurgical bile leaks can be associated with significant morbidity and even mortality, if not identified and treated at an early phase. Hepatobiliary iminodiacetic acid (HIDA) scan is an important test for detection of bile leaks in the postoperative abdomen. However, the lack of anatomical details on planar images can make interpretation difficult, especially in the setting of altered postsurgical anatomy. Familiarity with the expected postoperative appearance on HIDA scan and correlation with SPECT/CT or other imaging modalities when available are very important. The purpose of this review is to describe the expected findings on HIDA scan after common major abdominal surgeries that involve a change in biliary tree anatomy, and illustrate how to identify biliary leaks and avoid interpretation pitfalls.